Co-reporter:Ye Jiang, Honglie Shen, Tian Pu, Chaofan Zheng, Quntao Tang, Kai Gao, Jing Wu, Chunbao Rui, Yufang Li, Youwen Liu
Solar Energy 2017 Volume 142() pp:91-96
Publication Date(Web):15 January 2017
DOI:10.1016/j.solener.2016.12.007
•18.62% large area mc-Si solar cell with inverted pyramid structure was obtained.•Dimensions of inverted pyramids controlled by the acid treatment time.•500 nm inverted pyramid structure exhibited ideal solar cell performance.•A low-cost MACE and nano-rebuild process was proposed.In this paper, we report inverted pyramidal nanostructure based multi-crystalline silicon (mc-Si) solar cells with a high conversion efficiency of 18.62% in large size of 156 × 156 mm2 wafers. The nanostructures were fabricated by metal assisted chemical etching process followed by a post nano structure rebuilding (NSR) solution treatment. With increasing NSR treatment time, the reflectance and the dimensions of micro oval pits were both influenced. Resulting from both the light trapping ability and passivation efficiency, 500 nm inverted pyramid structure exhibited an ideal solar cell performance. The best solar cell showed a low reflectivity of 3.29% and a 0.91 mA cm−2 increase of short-circuit current density, and its efficiency was 0.45% higher than the acid textured solar cell. This technique presented a great potential to be a standard process for producing highly efficient mc-Si solar cells in the future.
Co-reporter:Quntao Tang, Honglie Shen, Hanyu Yao, Kai Gao, Ye Jiang, Chaofan Zheng, Wangyang Yang, Yufang Li, Youwen Liu, Lei Zhang
Solar Energy Materials and Solar Cells 2017 Volume 169(Volume 169) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.solmat.2017.05.025
•Size controllable fabrication of Quasi-inverted pyramid (QIP) was realized on c-Si.•The QIP possessed both efficient light trapping and superior wettability.•Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) may cast on QIP.•Over 3.6-fold reduction in material usage was achieved based on the QIP texture.•The QIP could be used for ultrathin c-Si/PEDOT:PSS hybrid solar cells.In this paper, a simple and cost-effective wet chemical method is presented to form quasi-inverted pyramids (QIP) on ultrathin c-Si for efficient light trapping and sufficient wettability. The QIP is fabricated by a well-known two-step Ag assisted chemical etching method followed by a post nanostructure rebuilding (NSR) process. The variation of [Ag+] realizes the modulation of QIP size from sub-micro scale to micro scale. The comparable average absorptance value of 50 µm c-Si with double-sided QIP fabricated under 0.5 mM [Ag+] (QIP-50) to that of 182 µm c-Si with double-sided conventional micro-scale pyramid in the spectral range of 300 – 1100 nm demonstrates an over 3.6-fold reduction in material usage. In comparison with nanopores-structured light-trapping configuration, the QIP-50 possesses much smaller specific surface area of ~2.39, which alleviates the surface recombination losses. After wet oxidation treatment, the water contact angle (WCA) of QIP-50 (35.73°) can achieve a comparable value to that of wet oxidized polished wafer (33.30°), demonstrating sufficient wettability of the QIP for high efficiency ultrathin c-Si/PEDOT:PSS hybrid solar cells. The finding of QIP with both efficient light trapping and superior wettability provides a new opportunity to improve the performance of ultrathin c-Si/PEDOT:PSS hybrid solar cells with a simple process at low cost.Download high-res image (262KB)Download full-size image
Co-reporter:Jinze Li, Honglie Shen, Huirong Shang, Yufang Li, Wenwen Wu
Materials Letters 2017 Volume 190(Volume 190) pp:
Publication Date(Web):1 March 2017
DOI:10.1016/j.matlet.2016.12.106
•A flexible solar cell with Ge layer between Ti substrate and Mo was fabricated.•Ge diffused into CZTSSe thin film and promoted grain growth.•Ge suppressed crack formation in Mo layer due to the reduced thermal stress.•The efficiency of Ge buffered flexible CZTSSe solar cell got an increase of 200%.Flexible CZTSSe thin film solar cells were prepared on Ti foil substrate. With adding a Ge buffer layer between the Ti foil substrate and the Mo back contact, CZTSSe thin film showed a better crystallization and less secondary phases. It was confirmed that Ge diffused into CZTSSe layer and had a promoting effect on Sn+4 state formation and stress release. The flexible CZTSSe solar cell with Ge buffer layer showed a conversion efficiency of 2.00%, which presented a 200% enhancement comparing to the solar cell without Ge buffer layer.Download high-res image (127KB)Download full-size image
Co-reporter:Hanyu Yao, Honglie Shen, Xiangrong Zhu, Jing Jiao, Jinze Li, Wei Wang
Ceramics International 2016 Volume 42(Issue 2) pp:2466-2471
Publication Date(Web):1 February 2016
DOI:10.1016/j.ceramint.2015.10.047
The CdxZn1−xS thin films were prepared by chemical bath deposition in a solution containing cadmium chloride, zinc chloride, thiourea, sodium citrate and ammonia. It was found CdxZn1−xS thin films could be successfully prepared at different CdCl2 concentrations from 0.04 M to 0.01 M. The morphological, structural, optical properties of CdxZn1−xS films fabricated by different Cd source concentrations were investigated by XRD, SEM and UV–vis-NIR spectroscopy, respectively. The CdxZn1−xS films prepared at 0.03 M and 0.02 M CdCl2 showed uniform, dense surface morphology and good crystallinity. With the concentration of CdCl2 in solution decreasing from 0.04 M to 0.01 M, the zinc content increased. Accordingly, the optical band gap increased from 2.45 eV to 3.07 eV. The photo-current response properties were mainly discussed. All the films showed obvious photoconductive phenomenon. The CdxZn1−xS film prepared at 0.02 M CdCl2 showed a best photo-current response, which presented fastest raise-up and fall-down photo-current when the light was turned on and off.
Co-reporter:Wei Wang, Honglie Shen, Lydia Helena Wong, Zhenghua Su, Hanyu Yao and Yufang Li
RSC Advances 2016 vol. 6(Issue 59) pp:54049-54053
Publication Date(Web):31 May 2016
DOI:10.1039/C6RA08604G
Quaternary Cu2ZnSnS4 (CZTS) thin films were prepared by a low-cost, simple and environmentally-friendly ink method. By depositing molecular solution on the nanoparticle thin film, the quality of as-prepared CZTS thin films was greatly improved (e.g. reduction of fine grain layer formation and improved crystallinity). The effect of the number of spin-coated layers from molecular solution on solar cell performance was investigated. The results indicated that the CZTS thin film had the best performance when 5 layers were spin-coated from molecular solution on the nanoparticle thin film. The crystallinity of the as-prepared CZTS thin film and the interface at Mo/CZTS was found to be obviously enhanced by addition of a molecular solution layer. Finally, a CZTS thin film solar cell with an efficiency of 4.92% has been fabricated.
Co-reporter:Zihao Zhai, Honglie Shen, Jieyi Chen, Jinze Li and Sanyang Zhang
RSC Advances 2016 vol. 6(Issue 48) pp:42353-42360
Publication Date(Web):28 Apr 2016
DOI:10.1039/C6RA04047K
Amorphous carbon (a-C) films were prepared by e-beam evaporation on silicon substrates. The effects of substrate temperature between room temperature and 600 °C were mainly studied. Raman spectroscopy, scanning electron microscopy, atomic force microscopy, UV-Vis-NIR and Hall-effect measurements were used to characterize the structure, morphology, roughness, transmittance and conductivity of a-C films, respectively. The results indicated the films obtained by e-beam evaporation were all graphite-like carbon films. The films deposited at 200 °C with a thickness of 75 nm presented the best performance with ID/IG of 4.50, FWHMG of 115.9 cm−1, an optical gap of 0.6 eV, a roughness of 0.825 nm and an electrical resistivity of 3.60 × 10−3 Ω cm. As the thickness reduced to about 8 nm while remaining at the same substrate temperature, the films still exhibited good structural quality, continuity and conductivity. SEM images from Ge/a-C/Si stacks and Ge/Si stacks confirmed the necessity of a-C buffer layer for smooth Ge film growth. Raman analysis of Ge films indicated that the crystalline quality of Ge films obtained from Ge/Si stacks was improved by inserting an a-C layer. The mechanism of a-C films as buffer layers was further explored by X-ray diffraction. The results suggested that a-C films with good properties prepared at such low temperature may be used as buffer layers for growing high quality Ge or GaAs films on Si.
Co-reporter:Jinze Li, Honglie Shen, Wei Wang, Jieyi Chen, Huirong Shang, Yufang Li, Zihao Zhai
Materials Letters 2016 Volume 172() pp:90-93
Publication Date(Web):1 June 2016
DOI:10.1016/j.matlet.2016.02.078
•Cu and Zn vertical distribution is controlled by a three-layer CZTS precursor.•Controlled distribution of element can promote the grain growth during annealing.•Efficiency of CZTSSe solar cell gets an increase of 3.54%.CZTSSe thin films based on three-layer precursors with Cu-poor and Zn-rich in top and bottom layer while stoichiometric in middle layer were prepared. Compared with CZTSSe thin film obtained from a stoichiometric single layer precursor, the crystallization of thin film from a three-layer precursor got enhanced. Element distribution and growth nuclei position in precursor played an important role on CZTSSe thin film formation and solar cell performance. The conversion efficiency of CZTSSe solar cell from a three-layer precursor attained an increase of 3.54% over that from a single layer precursor.Excess Zn in the bottom layer helps balance the composition there. Excess Zn in the upper layer promotes the growth of CZTSSe grains. Crystallization of CZTSSe film from a three-layer precursor got enhanced. An increase of 3.54% in conversion efficiency was obtained using a three-layer precursor.
Co-reporter:Weilong Chen, Honglie Shen, Xiangrong Zhu, Hanyu Yao, Wei Wang
Ceramics International 2015 Volume 41(Issue 10) pp:14008-14012
Publication Date(Web):December 2015
DOI:10.1016/j.ceramint.2015.07.013
WO3–TiO2–ZnO composite films were successfully prepared on glass substrates via a sol–gel method using polyethylene glycol 400 (PEG-400) as an organic additive. The influence of PEG-400 on microstructure and photochromic properties of the composite films was studied by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) and UV–vis–NIR spectrophotometer. The addition of PEG-400 could increase the amount of the adsorbed water in the WO3–TiO2–ZnO composite films, which plays a vital role in the photochromic process. SEM observation indicated that the aggregation of the particles in the films became serious when the addition amount of PEG-400 was above 0.5 g, for which a molecular ratio of WO3 and PEG-400 was 117:1. The photochromic property of the composite film firstly increased and then decreased with increasing amount of PEG-400. The WO3–TiO2–ZnO composite film with 0.5 g PEG-400 addition presented a best photochromism, which showed saturated photochromism in 60 s and bleached back to initial state in 10 h.
Co-reporter:Weilong Chen, Honglie Shen, Xiangrong Zhu, Zhengwei Xing, Sanyang Zhang
Ceramics International 2015 Volume 41(Issue 10) pp:12638-12643
Publication Date(Web):December 2015
DOI:10.1016/j.ceramint.2015.06.093
In this study, WO3–TiO2–ZnO ternary composite films were successfully prepared by a sol–gel method using citric acid as the coordination agent. The effect of citric acid concentration in the precursor solutions on microstructure and photochromic properties of the composite films was characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and a UV–vis–NIR spectrophotometer. Firstly, the citric acid improves the stability of the precursors and help to prepare homogeneous composited films. However, SEM observation indicates that the aggregation of the particles in the films occurrs when the concentration of citric acid is above 0.6 M. Secondly, all the samples preprared from the precursors with ctric acid present much better photochromism than the films with none citric acid in the precusors. Especially, the sample corresponding to 0.6 M citric acid displays best photochromism. Finally, for the sample corresponding to 0.6 M citric acid, the more detailed photochromic properties such as time dependence of UV–vis absorption and the bleaching absorption spectra were further investigated.
Co-reporter:Wei Wang, Honglie Shen, Jieyi Chen, Weilong Chen, Xiancong He
Advanced Powder Technology 2015 Volume 26(Issue 1) pp:275-279
Publication Date(Web):January 2015
DOI:10.1016/j.apt.2014.10.009
Highlights
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Cu2(FexZn1−x)SnS4 nanocrystals were fabricated by microwave irradiation.
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Cu2(FexZn1−x)SnS4 nanocrystals have a single phase, stoichiometric composition.
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The band gap of Cu2(FexZn1−x)SnS4 nanocrystals is tuned from 1.24 eV to 1.54 eV.
Co-reporter:Quntao Tang, Honglie Shen, Jing Jiao, Weilong Chen
Optical Materials 2015 Volume 39() pp:218-223
Publication Date(Web):January 2015
DOI:10.1016/j.optmat.2014.11.030
•Li+ and Er3+ co-doped ZnO film was prepared by sol–gel method.•The obtained film can convert both UV and NIR light to visible light.•The film was featured with a high transmittance of 86.8% in 400–900 nm.ZnO:Er, Li light conversion film has been successfully fabricated by sol–gel method. XRD measurement demonstrated the successful incorporation of Er3+ and Li+ into ZnO films. The as-grown film co-doped with 2% Er3+ and 3% Li+ is featured with a transmittance of about 86.8% in the range of 400–900 nm. Moreover, the film exhibits a visible light emission either being excited by 355 nm or 980 nm. Due to its relatively high transmittance characteristics and promising properties of converting both UV and NIR light to visible light, the developed film is considered to have a potential application in novel light conversion devices including solar cells.
Co-reporter:Haibin Huang 黄海宾 沈鸿烈
Journal of Wuhan University of Technology-Mater. Sci. Ed. 2015 Volume 30( Issue 3) pp:516-519
Publication Date(Web):2015 June
DOI:10.1007/s11595-015-1182-x
Boron-doped hydrogenated microcrystalline Germanium (μc-Ge:H) films were deposited by hot-wire CVD. H2 diluted GeH4 and B2H6 were used as precursors and the substrate temperature was kept at 300 °C. The properties of the samples were analyzed by XRD, Raman spectroscopy, Fourier transform infrared spectrometer and Hall Effect measurement with Van der Pauw method. It is found that the films are partially crystallized, with crystalline fractions larger than 45% and grain sizes smaller than 50 nm. The B-doping can enhance the crystallization but reduce the grain sizes, and also enhance the preferential growth of Ge (220). The conductivity of the films increases and tends to be saturated with increasing diborane-to-germane ratio \(R_{B_2 H_6 } \). All the Hall mobilities of the samples are larger than 3.8 cm2·V−1·s−1. A high conductivity of 41.3 Ω−1·cm−1 is gained at \(R_{B_2 H_6 } \)=6.7%.
Co-reporter:Wei Wang, Honglie Shen, Hanyu Yao, Jinze Li
Materials Letters 2014 Volume 125() pp:183-186
Publication Date(Web):15 June 2014
DOI:10.1016/j.matlet.2014.03.166
•Cu2FeSnS4 nanocrystals were fabricated by ultrasound-assisted microwave irradiation.•Cu2FeSnS4 nanocrystals have a single phase and a good stoichiometric composition.•Cu2FeSnS4 nanocrystals show stannite structure with an average size of about 5 nm.•The optical band gap of Cu2FeSnS4 nanocrystals is calculated to be about 1.35 eV.Cu2FeSnS4 nanocrystals were rapidly fabricated by ultrasound-assisted microwave irradiation using thioacetamide as a sulfur source. The phase structure, shape and composition of Cu2FeSnS4 nanocrystals were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS), respectively. The results showed that the phase of as-obtained Cu2FeSnS4 nanocrystals was stannite and the average size was about 5 nm. UV–vis absorption spectrum showed that the band gap of Cu2FeSnS4 nanocrystals was about 1.35 eV.
Co-reporter:Tianru Wu;Guqiao Ding;Haomin Wang;Lei Sun;Da Jiang;Xiaoming Xie;Mianheng Jiang
Advanced Functional Materials 2013 Volume 23( Issue 2) pp:198-203
Publication Date(Web):
DOI:10.1002/adfm.201201577
Abstract
A simple but efficient strategy to synthesize millimeter-sized graphene single crystal grains by regulating the supply of reactants in the chemical vapor deposition (CVD) process is demonstrated. Polystyrene is used as a carbon source. Pulse heating on the carbon source is utilized to minimize the nucleation density of graphene on copper foil, while a gradual increase in the temperature of the carbon source and the flow rate of hydrogen is adapted to drive the continuous growth of the graphene grains. As a result, the nucleation density of graphene grain can be controlled to as low as ≈100 nuclei/cm2, and a single crystal grain can grow up to dimensions of ≈1.2 mm. Raman spectroscopy, transmission electron microscopy (TEM), and electrical-transport measurements show that the graphene grains obtained are of high quality. The strategy presented provides very good controllability and enables the possibility of large graphene single crystals, which is of vital importance for practical applications.
Co-reporter:Tianru Wu, Honglie Shen, Lei Sun, Jiayi You and Zhihao Yue
RSC Advances 2013 vol. 3(Issue 24) pp:9544-9549
Publication Date(Web):15 Apr 2013
DOI:10.1039/C3RA23388J
In this report, we systematically studied low temperature fabrication of graphene from precursors containing cyclobenzene groups by remote plasma enhanced chemical vapor deposition. A new three-step growth procedure was developed with good control of the nucleation, domain growth and domain connection stages. Based on this growth procedure, high quality continuous graphene films could be obtained using naphthalene as the graphene precursor at temperatures lower than 600 °C. A transmittance of ∼96.4% and continuous optical images confirmed the successful fabrication of uniform single-layer graphene films with desirable quality at temperatures lower than 400 °C. Carrier mobility of graphene synthesized at 400 °C reached ∼682 cm2 V−1 s−1, indicating the samples are of reasonable quality. Low temperature graphene synthesis may pave the way for low cost large scale graphene fabrication, and for production of flexible substrates, especially polymer substrates.
Co-reporter:Zhihao Yue, Honglie Shen, Ye Jiang
Applied Surface Science 2013 Volume 271() pp:402-406
Publication Date(Web):15 April 2013
DOI:10.1016/j.apsusc.2013.01.216
Abstract
In this paper, pyramid-structured silicon wafers were etched in a reactive ion etching system at room temperature and without any negative voltage pulses to obtain antireflective nanostructures. The effects of the etching time, etching power and the flow ratio of the SF6 and O2 (FSF6/FO2) on the morphologies and reflective properties of the etched samples were studied. Scanning electron microscope was used to investigate the morphologies of etched samples. The surface reflectance measurements were carried out using UV–vis-NIR spectrophotometer. A reflectance of 4.72% from the etched surface in the wavelength range of 400–800 nm was obtained under etching time of 20 min, etching power of 150 W and FSF6/FO2 of 18 sccm/6 sccm. Meanwhile, samples etched with FO2 lower than 6 sccm can’t get low reflective silicon structure. Besides, the results show that overlong etching time of 30 min and too big etching power of 225 W would make the nanostructures too sparse to obtain a low reflectance.
Co-reporter:Wei Wang, Honglie Shen, Jinze Li
Materials Letters 2013 Volume 111() pp:5-8
Publication Date(Web):15 November 2013
DOI:10.1016/j.matlet.2013.08.038
•Hollow Cu2SnS3 nanoparticles were rapidly fabricated by microwave irradiation.•Cu2SnS3 nanoparticles have a single phase, stoichiometric composition.•The optical band gap of Cu2SnS3 nanoparticles is calculated to be about 1.25 eV.•A vesicle-template mechanism is proposed for the formation the hollow nanoparticles.Cu2SnS3 (CTS) nanoparticles were rapidly fabricated by microwave irradiation using l-cysteine as sulfur source. The phase structure, shape and composition of the CTS nanoparticles were investigated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS), respectively. The results showed that the phase of as-obtained CTS nanoparticles was cubic and the nanoparticles presented a hollow structure. A vesicle-template mechanism was proposed to explain the formation mechanism of the hollow CTS nanoparticles. UV–vis absorption spectra showed that the hollow CTS nanoparticles possess direct band gap energy of 1.25 eV.
Co-reporter:Hao Guan;Chao Gao
Journal of Materials Science: Materials in Electronics 2013 Volume 24( Issue 8) pp:2667-2671
Publication Date(Web):2013 August
DOI:10.1007/s10854-013-1153-y
Cu2ZnSnS4 (CZTS) films were obtained by sulfurizing (Cu, Sn) S/ZnS structured precursors prepared by a combination of the successive ionic layer absorption and reaction method and the chemical bath deposition method, respectively. The effect of sulfurization time on structure, composition and optical properties of these CZTS thin films was studied. The results of energy dispersive spectroscopy indicate that the annealed CZTS thin films are of Cu-poor and Zn-rich states. The X-ray diffraction studies reveal that Cu2−xS phase exists in the annealed CZTS thin film prepared by sulfurization for 20 min, while the Raman spectroscopy analysis shows that there is a small Cu2SnS3 phase existing in those by sulfurization for 20 and 40 min. The band gap (Eg) of the annealed CZTS thin films, which are determined by reflection spectroscopy, varies from 1.49 to 1.56 eV depending on sulfurization time. The best CZTS thin film is the one prepared by sulfurization for 80 min, exhibiting a single kesterite structure, dense morphology, ideal band gap (Eg = 1.55 eV) and high optical absorption coefficient (>104 cm−1).
Co-reporter:Lei Zhang;Jiayi You
Journal of Electronic Materials 2013 Volume 42( Issue 8) pp:2464-2469
Publication Date(Web):2013 August
DOI:10.1007/s11664-013-2608-x
We have investigated the effect of negative substrate bias on microcrystalline silicon films deposited on glass and stainless steel by hot-wire chemical vapor deposition (HWCVD) to gain insight into the effect of negative substrate bias on crystallization. Structural characterization of the silicon films was performed by Raman spectroscopy, x-ray diffraction, and scanning electron microscopy. It was found that the crystallinity of the films is obviously improved by applying the substrate bias, especially for films on stainless steel. At hot-wire temperature of 1800°C and negative substrate bias of −800 V, grain size as large as 200 nm was obtained on stainless-steel substrate with crystalline fraction 9% higher than that of films deposited on glass and 15% higher than that of films deposited without substrate bias. It is deduced that the improvement of the crystallinity is mainly related to the accelerated electrons emitted from the hot wires. The differences in this improvement between different substrates are caused by the different electrical potential of the substrates. A solar cell fabricated by HWCVD with −800 V substrate bias is demonstrated, showing an obviously higher conversion efficiency than that without substrate bias.
Co-reporter:Wei Wang;Xiancong He;Lei Sun
Journal of Materials Science: Materials in Electronics 2013 Volume 24( Issue 11) pp:4228-4232
Publication Date(Web):2013 November
DOI:10.1007/s10854-013-1389-6
Cu2ZnSnS4 (CZTS) thin films were prepared by a paste coating method as the absorb layer of solar cells. This method is more eco-friendly using ethanol as solvent and more convenient than traditional sol–gel method. The effects of sulfurization temperature on properties of thin film were studied. The results of X-ray diffraction and Raman spectroscopy showed the formation of kesterite structure of CZTS films. The scanning electron microscopy images revealed that CZTS thin film obtained at 550 °C were compact and uniform. The optical band gap of the CZTS film was about 1.5 eV, and the CZTS film had an obvious optoelectronic response. Moreover, CZTS solar cell was prepared with a conversion efficiency of 0.47 %.
Co-reporter:Wei Wang;Feng Jiang
Journal of Materials Science: Materials in Electronics 2013 Volume 24( Issue 6) pp:1813-1817
Publication Date(Web):2013 June
DOI:10.1007/s10854-012-1017-x
In this study, ball cactus-like kesterite Cu2ZnSnS4 microparticles were successfully and rapidly fabricated by chemical solution with microwave irradiation using ethylene glycol as a solvent. And then CZTS thin film was prepared by ink-print method. The samples were characterized by means of X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, energy dispersive spectrometer, scan electron microscopy, transmission electron microscopy, and UV–vis-NIR spectroscopy. The results showed that the as-prepared microparticles had single phase, stoichiometric composition, a ball cactus-like shape with a diameter about 300 nm and that CZTS thin film had large grains and high crystallinity.
Co-reporter:Hao Guan;Chao Gao
Journal of Materials Science: Materials in Electronics 2013 Volume 24( Issue 5) pp:1490-1494
Publication Date(Web):2013 May
DOI:10.1007/s10854-012-0960-x
Thin films of Cu2SnS3 and Cu3SnS4 were obtained by sulfurizing (Cu, Sn)S structured precursors prepared by successive ionic layer absorption and reaction method. The results of energy dispersive spectroscopy (EDS) indicate that some loss in Sn with increasing sulfurization temperature. For the sulfurization temperatures of 380, 400 and 500 °C, tetragonal (I-42m) Cu2SnS3, cubic (F-43m) Cu2SnS3 and tetragonal (I-42m) Cu3SnS4 were formed, respectively. The combination of X-ray diffraction (XRD) results and Raman spectroscopy reveals that there are small Cu2−xS phase existing in the CTS thin films (400 and 500 °C). Scanning electron microscopy was used to study the morphology of the layers. The ternary compounds present a high optical absorption coefficient (>104 cm−1). The band gap energy (Eg) of the CTS thin films is estimated by reflection spectroscopy. The ternary compounds present a high optical absorption coefficient (>104 cm−1). The estimated band gap energy (Eg) is 1.05 eV for tetragonal (I-42m) Cu2SnS3, 1.19 eV for cubic (F-43m) Cu2SnS3, and 1.22 eV for tetragonal (I-42m) Cu3SnS4.
Co-reporter:Hao Guan;Chao Gao
Journal of Materials Science: Materials in Electronics 2013 Volume 24( Issue 9) pp:3195-3198
Publication Date(Web):2013 September
DOI:10.1007/s10854-013-1227-x
The influence of annealing atmosphere on the phase formation of Cu–Sn–S ternary compound by SILAR method was studied. Structural, optical and electrical properties of the compound were studied for the samples annealed at 420 °C for 1 h in different atmosphere. X-ray diffraction and Raman spectra showed that Cu2SnS3 cubic phase was obtained in an atmosphere of nitrogen and sulfur vapor mixture, while Cu4SnS4 orthorhombic phase was obtained in H2S atmosphere. An optical band-gap of 0.98 eV was obtained for Cu2SnS3 and 0.93 eV for Cu4SnS4 phase. The activation energies are about 0.1 eV for Cu2SnS3 phase and 0.06 eV for the Cu4SnS4 phase in high temperature region, but those are about 0.007 and 0.009 eV for them in low temperature region respectively.
Co-reporter:Wei Wang, Honglie Shen, Xiancong He
Materials Research Bulletin 2013 48(9) pp: 3140-3143
Publication Date(Web):
DOI:10.1016/j.materresbull.2013.04.078
Co-reporter:Tianru Wu, Honglie Shen, Lei Sun, Bin Cheng, Bin Liu, and Jiancang Shen
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 4) pp:2041
Publication Date(Web):March 30, 2012
DOI:10.1021/am300014c
Graphene was synthesized by chemical vapor deposition using polystyrene as the solid carbon source. The number of graphene layers could be controlled by regulating the weight of polystyrene under atmospheric pressure at 1000 °C. Silver nanoparticles were then deposited on the graphene by a citrate reduction method. The interaction between graphene and silver was investigated by suface-enhanced Raman scattering spectra and X-ray photoelectron spectroscopy. The change in the G band position indicates n-type doping of the graphene due to an interaction between the silver and the graphene. Silver interlayer doped four-layer graphene shows a sheet resistance of 63 Ω/sq and a light transmittance of 85.4% at 550 nm. The optical and electrical quality of graphene exceeds the minimum industry standard for indium tin oxide replacement materials. It is clearly understood that the environmental sheet resistance stability of the interlayer doped graphene film is better than that of surface doped graphene sheets. The presence of graphene at the surface also acts as a protective layer for the inner silver ions and clustersKeywords: graphene; monolayer; polystyrene; pressure; silver nitrate;
Co-reporter:Hongjie Lv, Honglie Shen, Ye Jiang, Chao Gao, Han Zhao, Jiren Yuan
Applied Surface Science 2012 Volume 258(Issue 14) pp:5451-5454
Publication Date(Web):1 May 2012
DOI:10.1016/j.apsusc.2012.02.033
Abstract
Porous-pyramids structured silicon surface was prepared and its influence on the reflectance of the silicon surface was studied. The porous-pyramids structured surface was prepared by electrochemical etching in HF/C2H5OH solution after texturization in NaOH/IPA solution. The average reflectance of the surface in the range of 400–800 nm was as low as 1.9%. The optical photographs and SEM images of the surfaces prepared under optimized condition were investigated. The porous-pyramids structured surface has a gradient-index multilayer structure (i.e., the refraction index of the structure increase from the top to the bottom). A formula that describes the relationship between the reflectance and the index of refraction was used to explain the excellent broadband antireflection of the multilayer silicon surface. The technique of this paper may be valuable in the texturization process for high-efficiency silicon solar cells.
Co-reporter:Yunguang Zhu;Haili Chen
Rare Metals 2012 Volume 31( Issue 1) pp:43-47
Publication Date(Web):2012 February
DOI:10.1007/s12598-012-0460-4
Nano-TiO2/Co4Sb11.7Te0.3 composites were prepared by mechanical alloying (MA) and cold isostatic pressing (CIP) process. The phase composition, microstructure, and thermoelectric properties were characterized. The diffraction spectra of all samples well corresponds to CoSb3 skutterudite diffraction plane. TiO2 agglomerates into irregular clusters. They locate at the grain boundaries or some are distributed on the surface of Co4Sb11.7Te0.3 particles. For composites with high TiO2 content (0.6% and 1.0% TiO2), the phonon scattering by TiO2 particle, pores, and small size grains can result in a remarkable reduction in thermal conductivity. The maximum value of ZT is 0.79 for sample with 0.6 wt.% TiO2 at 700 K, which is 11% higher than that of non-dispersed sample.
Co-reporter:Lei Zhang;Jiayi You
Journal of Materials Science: Materials in Electronics 2012 Volume 23( Issue 7) pp:1279-1283
Publication Date(Web):2012 July
DOI:10.1007/s10854-012-0786-6
Poly-crystalline silicon (poly-Si) films were fabricated by rapid thermal annealing (RTA) of amorphous silicon films which were deposited on quartz by hot wire chemical vapor deposition. An insertion of Cr layer can significantly suppress the peeling of Si films during the RTA process. The effect of RTA parameters on the structural properties of poly-Si films was investigated by Raman spectroscopy, X-ray diffraction and scanning electron microscopy. The results show that the crystallinity of the poly-Si films is increased with the increase of RTA temperature and duration. A sharp peak at about 520 cm−1 is observed in the Raman spectra of poly-Si films annealed at 900 and 1,100 °C for 15 s indicating the excellent crystallinity of the poly-Si films fabricated by RTA. Poly-Si films with high crystalline fraction of 97.3 % were obtained by RTA at 1,100 °C for 20 s.
Co-reporter:Yunguang Zhu;Hao Guan
Journal of Materials Science: Materials in Electronics 2012 Volume 23( Issue 12) pp:2210-2215
Publication Date(Web):2012 December
DOI:10.1007/s10854-012-0754-1
Using CoCl2 and SbCl3 as precursors and NaBH4 as reducing agent, we obtained nano CoSb3 particles of about 10 nm with the assistance of microwave radiation. Different Sb/Co ratio and different microwave radiation time were used to prepare CoSb3. The results show that single CoSb3 phase was synthesized successfully under the condition of Sb/Co ratio with 5:1 and microwave radiation time with 5 min. The samples with microstructure and nanostructure were synthesized respectively by cold isostatic pressing and sintering method, and their thermoelectric properties were studied. Due to its powder preparation method and its small grain size, the sample with nanostructure has lower electrical resistivity and thermal conductivity than the sample with microstructure. The maximum ZT value was found to be 0.11 at 650 K in the sample with nanostructure, which is about 10 times higher than that of the sample with microstructure.
Co-reporter:Chao Gao, Honglie Shen
Thin Solid Films 2012 Volume 520(Issue 9) pp:3523-3527
Publication Date(Web):29 February 2012
DOI:10.1016/j.tsf.2011.12.077
Orthorhombic stannous sulfide (SnS) films were prepared by chemical bath deposition in which stannous dichloride (SnCl2), ammonium citrate (C6H5O7(NH4)3) and sodium thiosulfate (Na2S2O3) were used as tin source, chelating reagent and sulfur source, respectively. The influence of the deposition temperatures and the concentration ratios of Na2S2O3/SnCl2 on the morphologies, compositions and electrical and optical properties of the SnS films were investigated. The results show that the compactness of the SnS films gets worse when the deposition temperature increases, while the compactness of the films gets better when the concentration ratio of Na2S2O3/SnCl2 increases. The compositions of the films (the molar ratio of S/Sn ranges from 46.7:53.3 to 48.9:51.1) are all close to the stoichiometric ratio of SnS, and the molar ratio of S/Sn in the films increases as the deposition temperature and the concentration ratio of Na2S2O3/SnCl2 increase. The optical bandgaps of the SnS films are in the range of 1.01 eV–1.26 eV. The dark conductivities and photo conductivities of the SnS films all increase as the deposition temperature and the concentration ratio of Na2S2O3/SnCl2 increase.Highlights► Orthorhombic SnS films were prepared by chemical bath deposition. ► Smooth and compact SnS films were obtained. ► Temperature and composition of the deposition solution influence the film properties. ► Mechanism linking deposition parameters and SnS film properties are discussed.
Co-reporter:Honglie Shen, Tianru Wu, Yuanyuan Pan, Lei Zhang, Bin Cheng, Zhihao Yue
Thin Solid Films 2012 Volume 522() pp:36-39
Publication Date(Web):1 November 2012
DOI:10.1016/j.tsf.2012.02.011
The nanocrystalline cubic SiC (nc-3C–SiC) films were deposited on quartz chips from SiH4–C2H2–H2 mixture by hot wire chemical vapor deposition. During the deposition, the total gas pressure and the substrate temperature were kept at 800 Pa and 350 °C. The films were characterized by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and UV–VIS–NIR spectroscopy. It was found that the film structure changed from microcrystalline Si to nc-3C–SiC between 1700 °C and 1800 °C. The optical band gap of deposited films increased from 1.6 to 2.5 eV by varying the filament temperature from 1600 °C to 2000 °C. The intensities of CH and SiC bonds were found to be the key parameters, controlling their optical and structural properties. Furthermore, the crystallinity of SiC films was promoted with increasing the filament temperature, due to the large amount of H radicals which etches the amorphous network structure and the grain boundaries.
Co-reporter:Chao Gao, Honglie Shen, Lei Sun
Applied Surface Science 2011 Volume 258(Issue 1) pp:89-92
Publication Date(Web):15 October 2011
DOI:10.1016/j.apsusc.2011.08.011
Abstract
Nanowall shaped Bi2S3 films were prepared by chemical bath deposition in which ammonium citrate and thioacetamide were used as chelating reagent and sulfur source, respectively. The nanowall Bi2S3 films show large-surface-area nanowall shaped morphology. It is found that the pH value (pH = 6 or pH = 6.5) of the solution is a crucial parameter to obtain the nanowall shaped Bi2S3 films. The composition of the nanowall Bi2S3 films is close to the stoichiometric ratio of Bi2S3. The absorption edge of the nanowall shaped Bi2S3 films is located at around 900 nm, indicating that the optical bandgap of the Bi2S3 films is around 1.4 eV. The nanowall Bi2S3 films show obvious photo-sensitivity. The photo-to-dark conductivity ratios of the nanowall Bi2S3 films prepared at pH = 6 and pH = 6.5 are all around 50. This value is around five times than that of the non-nanowall shaped Bi2S3 films which is prepared at pH = 7.
Co-reporter:Tianru Wu, Honglie Shen, Bin Cheng, Yuanyuan Pan, Bing Liu, Jiancang Shen
Applied Surface Science 2011 Volume 258(Issue 3) pp:999-1003
Publication Date(Web):15 November 2011
DOI:10.1016/j.apsusc.2011.06.165
Abstract
In this work, hydrogenated amorphous silicon carbide (α-Si1−xCx:H) and nanocrystalline SiC (nc-SiC) thin films were deposited by hot wire CVD (HWCVD) using SiH4/C2H2/H2 gas mixtures. It was found that the films prepared under low gas pressure were α-Si1−xCx:H and those prepared under high gas pressure were nc-3C-SiC. The α-Si1−xCx:H films showed enhanced density of C–Hn and Si–C bonds with increasing C2H2 fraction, which induced an increase in optical gap from 1.8 to 3.0 eV. For the deposition process of nc-SiC, the Eg opt of the deposited films varied from 1.9 eV to 2.5 eV as the filament temperature increased from 1700 to 2100 °C. The deposition rate decreased rapidly from 5.74 nm/min to 0.8 nm/min with increasing TF.
Co-reporter:Feng Jiang, Honglie Shen, Chao Gao, Bing Liu, Long Lin, Zhou Shen
Applied Surface Science 2011 Volume 257(Issue 11) pp:4901-4905
Publication Date(Web):15 March 2011
DOI:10.1016/j.apsusc.2010.12.143
Abstract
SnS films have been prepared by a novel two-stage process. It involved sputtering of Sn film on glass substrate and sulfurization of the thin metallic tin precursor layers in a vacuum furnace. The X-ray diffraction results showed that the SnS layers had orthorhombic structure and (0 4 0) preferential growth is more and more obvious with the increase of sulfurization time. The SnS film obtained by this work shows high optical absorption efficiency, and the film has a direct optical band gap of about 1.3 eV. The films show p-type conductivity and the resistivity of SnS film decreased obviously under illumination.
Co-reporter:Chao Gao, Honglie Shen, Lei Sun, Zhou Shen
Applied Surface Science 2011 Volume 257(Issue 17) pp:7529-7533
Publication Date(Web):15 June 2011
DOI:10.1016/j.apsusc.2011.03.080
Abstract
Bismuth sulfide (Bi2S3) films were chemically deposited by a novel deposition system in which ammonium citrate was used as the chelating reagent. Two sulfur source thioacetamide (TA) and sodium thiosulfate (Na2S2O3) were used to prepare Bi2S3 films. Both the as-prepared films have amorphous structure. However, annealing can improve the crystallization of the films. The composition of the films prepared by TA and Na2S2O3 are all deviate from the stoichiometric ratio of Bi2S3. The Bi2S3 films are all homogeneous and well adhered to the substrate. The optical properties of the Bi2S3 films are studied. The electrical resistivity of the as-prepared films are all around 7 × 103 Ω cm in dark, which decreases to around 1 × 103 Ω cm under 100 mW/cm2 tungsten–halogen illumination. After the annealing, the dark resistivity of the Bi2S3 film prepared by TA decreases by four magnitudes. In contrast, the dark resistivity of the Bi2S3 film prepared by Na2S2O3 only decreases slightly.
Co-reporter:Chao Gao, Honglie Shen, Lei Sun
Applied Surface Science 2011 Volume 257(Issue 15) pp:6750-6755
Publication Date(Web):15 May 2011
DOI:10.1016/j.apsusc.2011.02.116
Abstract
SnS (stannous sulfide) films were prepared by chemical bath deposition in which a novel chelating reagent ammonium citrate was used. The film has a zinc blende structure or an orthorhombic structure which is determined by the pH value and the temperature of the deposition solution. The reason for this result is considered to be that SnS films prepared under different conditions have different deposition mechanisms (ion-by-ion mechanism for the zinc blende structured SnS and hydroxide cluster mechanism for the orthorhombic structured SnS). The prepared SnS films are homogeneous and well adhered. SEM images show that the SnS films with different structures have different surface morphologies. Electrical test shows that the resistivity of the films is as low as 420 Ω cm and 3300 Ω cm for orthorhombic and zinc blende SnS films, respectively, which are much lower than the ever reported values. Persistent photoconductivity (PPC) phenomena are observed for both the films with zinc blende and orthorhombic structures by photo-current responses measurement. The optical bandgaps of the SnS films are determined to be 1.75 eV and 1.15 eV for zinc blende structure and orthorhombic structure, respectively.
Co-reporter:Chao Gao, Honglie Shen, Lei Sun, Zhou Shen
Materials Letters 2011 Volume 65(Issue 9) pp:1413-1415
Publication Date(Web):15 May 2011
DOI:10.1016/j.matlet.2011.02.017
SnS (stannous sulfide) films were prepared by chemical bath deposition in which a novel chelating reagent ammonium citrate was used. The film has a zinc blende structure or orthorhombic structure which is determined by the pH value of the deposition solution (zinc blende structure at pH = 5 and orthorhombic structure at pH = 6). The reason for this result may be that SnS films prepared at different pH values have different deposition mechanisms, which results in different structures. The prepared SnS films are all smooth and well adhered. The optical bandgaps of the SnS films are determined to be 1.75 eV and 1.12 eV for zinc blende structure and orthorhombic structure, respectively.
Co-reporter:Yunguang Zhu, Honglie Shen, Lianyong Zuo, Hao Guan
Solid State Communications 2011 Volume 151(Issue 19) pp:1388-1393
Publication Date(Web):October 2011
DOI:10.1016/j.ssc.2011.06.008
Co-reporter:Chao Gao, Honglie Shen, Lei Sun, Haibin Huang, Linfeng Lu, Hong Cai
Materials Letters 2010 Volume 64(Issue 20) pp:2177-2179
Publication Date(Web):31 October 2010
DOI:10.1016/j.matlet.2010.07.002
Polycrystalline SnS thin films have been prepared by a modified SILAR (successive ionic layer adsorption and reaction) method, in which certain quantity of NH4Cl was added to the cation precursor solution. The films have a novel zinc blende structure. The obtained SnS films are slightly rich in Sn component. There are small amounts of O impurity existing in the films, but no other impurity such as N or Cl is found in the films. The dark conductivity of the films is about 10–6Ω–1cm–1. The polycrystalline films have a direct (forbidden) bandgap of 1.71 eV. The optical adsorption coefficient is above 104 cm–1 when the photon energy is larger than 1.4 eV.
Co-reporter:Chao Gao, Jiangtian Li, Zhichao Shan, Fuqiang Huang, Honglie Shen
Materials Chemistry and Physics 2010 Volume 122(Issue 1) pp:183-187
Publication Date(Web):1 July 2010
DOI:10.1016/j.matchemphys.2010.02.030
A novel In2S3/TiO2 composite with visible-light photocatalytic activity was prepared by a chemical precipitation method and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope and UV–vis diffuse reflectance spectroscopy. Under both UV- and visible-light irradiation, the In2S3/TiO2 composite shows good photocatalytic activity to degrade methyl orange, ascribed to the absorption of visible light by In2S3 sensitizer and enhanced separation of photoinduced electron–hole pairs in the composite semiconductors.
Co-reporter:Zhengxia Tang, Honglie Shen, Haibin Huang, Linfeng Lu, Yugang Yin, Hong Cai, Jiancang Shen
Thin Solid Films 2009 Volume 517(Issue 19) pp:5611-5615
Publication Date(Web):3 August 2009
DOI:10.1016/j.tsf.2009.01.189
High quality polycrystalline silicon (poly-Si) thin films without Si islands were prepared by using aluminum-induced crystallization on glass substrates. Al and amorphous silicon films were deposited by vacuum thermal evaporation and radio frequency magnetron sputtering, respectively. The samples were annealed at 500 °C for 7 h and then Al was removed by wet etching. Scanning electron microscopy shows that there are two layers in the thin films. After the upper layer was peeled off, the lower poly-Si thin film was found to be of high crystalline quality. It presented a Raman peak at 521 cm− 1 with full width at a half maximum of 5.23 cm− 1, which is similar to c-Si wafer.
Co-reporter:Yunguang Zhu, Honglie Shen, Lianyong Zuo, Hao Guan
Solid State Communications (October 2011) Volume 151(Issue 19) pp:1388-1393
Publication Date(Web):1 October 2011
DOI:10.1016/j.ssc.2011.06.008
Co4Sb12−xTex compounds were prepared by mechanical alloying combined with cold isostatic pressing, and the effects of Te doping on the thermoelectric properties were studied. The electronic structure of Te-doped and undoped CoSb3 compounds has been calculated using the first-principles plane-wave pseudo-potential based on density functional theory. The experimental and calculated results show that the value of the solution limit x of Te in Co4Sb12−xTex compounds is between 0.5 and 0.7. The Fermi surface of CoSb3 is located between the conduction band and the valence band, and its electrical resistivity decreases with increasing temperature. The density of states is mainly composed of Co 3d and Sb 5p electrons for intrinsic CoSb3.The Fermi surface of Te-doped compounds moves to the conduction band and its electrical resistivity increases with increasing temperature, exhibiting n-type degenerated semiconductor character. Under the conditions of the experiment, the maximum value 2.67 mW/m K2 of the power factor for Co4Sb11.7Te0.3 is obtained at 600 K; this is about 14 times higher than that of CoSb3.Highlights► Co4Sb12−xTex compounds were synthesized by mechanical alloying combined with cold isostatic pressing for the first time. ► The electronic structure of Te-doped and undoped CoSb3 compounds was calculated using CASTEP code. ► The Te atom makes a considerable contribution to the valence band of Te-doped CoSb3. ► The calculated results of the electronic structure are in good agreement with the experimental results.
Co-reporter:Zihao Zhai, Honglie Shen, Jieyi Chen, Ye Jiang, Quntao Tang
Carbon (June 2017) Volume 117() pp:
Publication Date(Web):June 2017
DOI:10.1016/j.carbon.2017.03.006
A study based on the structural, optical and electrical properties of amorphous carbon (a-C) films by hot-filament chemical vapor deposition (HFCVD) with acetylene is reported. Effect of substrate temperature ranging from 450 °C to 850 °C and cooling method including hydrogen, argon and furnace cooling was mainly investigated. The structural transitions from a-C to nanocrystalline graphite (nc-G) and from nc-G to graphite were observed by raising substrate temperature. Hydrogen content in a-C films decreased sharply as the temperature increased from 450 °C to 550 °C, which corresponded to the high growth rate and large roughness at 550 °C. The influence of cooling method on properties of a-C films was attributed to different compressive stress produced by the volume shrinkage during cooling process. The films grown at 850 °C followed by hydrogen cooling exhibited the best performance with an optical gap of 1.2 eV, a mobility of 3.18 cm2/(V·s) and an electrical resistivity of 7.79 × 10−3 Ω·cm, which were comparable to the reported properties of a-C films by other methods. These results indicated that HFCVD is a good method to synthesize high quality a-C films.
Co-reporter:Quntao Tang, Honglie Shen, Hanyu Yao, Ye Jiang, Chaofan Zheng, Kai Gao
Ceramics International (January 2017) Volume 43(Issue 1) pp:
Publication Date(Web):January 2017
DOI:10.1016/j.ceramint.2016.10.048
In this paper, flexible, robustly adhesive, surface smooth and oxide-resistive AgNWs/AZO composite transparent conductive films (TCFs) were prepared by spin-coating solvothermal derived AgNWs followed by magnetron sputtering AZO protective layer, after which, annealing treatment at 200 ℃ for 20 min was adopted to further increase the performance of the composite film. The samples were characterized by means of X-ray diffraction, Raman spectroscopy, scan electron microscopy, scanning probe microscope, UV–Vis spectrophotometer and four point probe. The best result of AgNWs/AZO composite films was the one with a transmittance of 85% at 550 nm accompanied with a low sheet resistance of 19 Ω/□ by controlling the spin-coating times fixed at three. The figure of merit for the composite TCFs was 10.4, which was larger than the value of 8.8 for commercial ITO film. These amazing results would render the AgNWs /AZO composite TCFs an ideal candidate to replace conventional ITO for its potential application in flexible devices including OPV and OLED.
Co-reporter:Chao Gao, Honglie Shen, Tianru Wu, Lei Zhang, Feng Jiang
Journal of Crystal Growth (1 October 2010) Volume 312(Issue 20) pp:3009-3013
Publication Date(Web):1 October 2010
DOI:10.1016/j.jcrysgro.2010.07.001
Zinc blende structure tin sulfide (SnS) films have been prepared by successive ionic layer adsorption and reaction (SILAR) method. It is found that both the annealing and addition of NH4Cl or NaCl to cation solution during the SILAR process can promote the crystallization of SnS films. The growth mechanism for this novel structure considered that the initial distribution of cations on the substrate surface during the cation adsorption process is the crucial factor that determines the structure of the final production. Because Cl− anions can complex with Sn2+ cations, when the concentration of Cl− in the cation precursor solution increases, more [SnCl]+ complex ions are adsorbed on the substrate. These [SnCl]+ ions assemble more orderly than Sn2+ ions because of the polarity of ions, so crystallized SnS films can be obtained when NH4Cl or NaCl is added to the cation solution.
Co-reporter:Jinze Li, Honglie Shen, Jieyi Chen, Yufang Li and Jiale Yang
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 41) pp:NaN28834-28834
Publication Date(Web):2016/09/27
DOI:10.1039/C6CP05671G
Ge-doped CZTSSe thin films were obtained by covering a thin Ge layer on CZTS precursors, followed by a selenization process. The effect of the Ge layer thickness on the morphologies and structural properties of Ge-doped CZTSSe thin films were studied. It was found that Ge doping could promote grain growth to form a compact thin film. The lattice shrank in the top-half of the film due to the smaller atomic radius of Ge, leading to the formation of tensile stress. According to thermodynamic analysis, Sn was easier to be selenized than Ge. Thus, Ge preferred to remain on the surface and increased the surface roughness when the Ge layer was thin. CZTSe was easier to form than Ge-doped CZTSe, which caused difficulty in Ge doping. These results offered a theoretical and experimental guide for preparing Ge-doped CZTSSe thin films for the potential applications in low-cost solar cells. With a 10 nm Ge layer on the top of the precursor, the conversion efficiency of the solar cell improved to 5.38% with an open-circuit voltage of 403 mV, a short-circuit current density of 28.51 mA cm−2 and a fill factor of 46.83% after Ge doping.
