Linna Zhu

Fluorine-substituted benzothiadiazole (BT) was introduced as a core structure to construct new hole transport materials. Planar perovskite solar cells with conventional materials (CH3NH3PbI3−xClx) were fabricated. The perovskite solar cells using monofluorinated BT exhibit a leading efficiency of 18.54% with a FF as high as 81%.

Molecular engineering to enhance perovskite solar cell performance: Incorporation of benzothiadiazole as core unit for low cost hole transport materials

Co-reporter:Fei Wu, Yu Ji, Rui Wang, Yahan Shan, Linna Zhu

Dyes and Pigments 2017 Volume 143(Volume 143) pp:

Publication Date(Web):1 August 2017

DOI:10.1016/j.dyepig.2017.04.059

•Benzothiadiazole is used as the core structure for hole transport material.•The new HTM JY5 has matched energy level with perovskite.•JY5 shows good hole extraction and hole transporting ability.•A champion efficiency of 16.87% was achieved with JY5 as HTM.•JY5 is of low cost and could be potential alternative for Spiro-OMeTAD.Through molecular engineering, a benzothiadiazole unit is incorporated as the core structure to generate a new hole transport material JY5. Cyclic voltammetry measurement suggests matched energy level of JY5 with the perovskite materials. TGA and DSC show excellent thermal stability of JY5. Hole mobility and PL decay experiments indicate good hole transport ability in JY5. As a result, perovskite solar cells utilizing JY5 as HTM outperforms the biphenyl centered analogue, and a champion efficiency of 16.87% was achieved among the HTMs studied in this work, with short-circuit current (Jsc) of 21.06 mA cm−2, open-circuit voltage (Voc) of 1.06 V, and fill factor (FF) of 0.76. The high efficiency as well as low costs make it potential alternative to the highly cost Spiro-OMeTAD.

Gelation-induced emission enhancement in a “butterfly”-shaped π-conjugated organogelator and its reversible response to acid/base

Co-reporter:Yahan Shan, Luxi Tan, Cheng Zhong, Fei Wu, Linna Zhu

Tetrahedron Letters 2017 Volume 58, Issue 35(Issue 35) pp:

Publication Date(Web):30 August 2017

DOI:10.1016/j.tetlet.2017.07.073

•A new organogelator SY1 without normal auxiliary groups is synthesized.•SY1 has the gelation-induced emission enhancement character.•The gel of SY1 exhibits reversible response to acid/base.In this work, we find that a new “butterfly”-shaped π-conjugated molecule, namely SY1, has the ability to undergo gelatinization in several solvents. Even though the SY1 moiety is not modified by normal auxiliary groups, the gel formation/dissolution process is reversible for many cycles upon heating and cooling processes, indicating that the gel of SY1 has reliable stability during gelation. Results also demonstrate that the gel of SY1 exhibits bright orange emission with the gelation-induced emission enhancement character. Interestingly, the gel shows reversible response upon acid/base treatment. After addition of normal acid, the gel turns into darker colour and its fluorescence undergoes quenching. Increasing pH value of the system by adding NaOH aq. leads to fluorescence emission recovery. Therefore, SY1 represents a π-conjugated organogelator without normal auxiliary groups, and exhibits gel-induced emission enhancement as well as reversible response to acid/base. The findings in this work enrich our fundamental understanding of the organogel system.A “butterfly”-shaped π-conjugate molecule SY1 is found to gelatinize several solvents, with the gelation-induced emission enhancement character. The SY1 gel shows reversible response to acid/base treatment and heat/cooling processes.Download high-res image (86KB)Download full-size image

Fast preparation of compact and stable perovskite films derived from PbCl2 and Pb(Ac)2·3H2O mixed-lead-halide precursors

Co-reporter:Fei Wu, Linna Zhu

Solar Energy Materials and Solar Cells 2017 Volume 167(Volume 167) pp:

Publication Date(Web):1 August 2017

DOI:10.1016/j.solmat.2017.03.030

•PbCl2 and Pb(Ac)2·3H2O were mixed to prepare perovskite film.•Compact and full-coverage perovskite film with large grain size is obtained.•Perovskite film prepared from mixed precursors show good stability in air.•The highest efficiency of 14.77% is obtained from the mixed precursors.In this work, lead chloride (PbCl2) and lead acetate trihydrate (Pb(Ac)2·3H2O) mixed precursors are introduced to prepare perovskite films. PbCl2 has been reported to enhance crystallinity but long annealing time is required. Pb(Ac)2·3H2O is used because it is cheap and easy to get, and lead acetate offers fast crystallization process, meanwhile the trihydrate might improve the film stability. With an optimal blending ratio of the two precursors (1:1 mol ratio), compact and full-coverage perovskite film with large grain sizes (>1 µm) are obtained, and the speed of perovskite film formation is greatly accelerated. Moreover, the film prepared in a 1:1 mol ratio of the two precursors exhibits good moisture liability for several days under around 70% RH environment. As a result, the PbCl2: Pb(Ac)2·3H2O (1:1) results in the highest efficiency of 14.77%. The findings in this work provide a facile way to improve the perovskite film quality and stability.PbCl2 and Pb(Ac)2·3H2O mixed precursors were introduced to prepare perovskite films. With 1:1 mol ratio of the two precursors, compact and full-coverage perovskite film with large grain sizes (>1 µm) and good stability in ambient condition were obtained.Download high-res image (227KB)Download full-size image

Enhanced photovoltaic performance of ternary solar cells by doping a new squaraine derivative

Co-reporter:Linna Zhu, Rui Wang, Jianhui Qiao, Fei Wu

Dyes and Pigments 2016 Volume 132() pp:20-26

Publication Date(Web):September 2016

DOI:10.1016/j.dyepig.2016.04.038

•Squaraine based NIR dye is synthesized and applied in ternary solar cells.•The NIR dye exhibits a quite broad absorption band with FWHM of 169 nm.•The energy level of the dye matched well with P3HT and PC71BM.•PCE of 3.93% is achieved for a P3HT:PC71BM blend with 2.4 wt % of TPE-SQ.Ternary blend solar cells have been proved to be an efficient way to harvest more photons over the near-IR region. In this work, the effect of adding a NIR absorbing squaraine derivative (TPE-SQ) into a conventional P3HT:PC71BM based bulk heterojunction photovoltaic cell is investigated. The new NIR dye exhibits a quite broad absorption band with full-width at half maximum of 169 nm in the film state, with the absorption edge extending to more than 850 nm. The near infrared absorption of the ternary system is enhanced by the blended squaraine component, and the energy level of the third component matched well with the donor and the acceptor material, leading to increased short-circuit current as well as elevated power conversion efficiency compared to the P3HT:PC71BM binary solar cell. The highest efficiency of 3.93% is achieved for a P3HT:PC71BM blend with 2.4 wt % of TPE-SQ.A new NIR absorbing squaraine derivative TPE-SQ is synthesized and applied in ternary solar cells. The highest efficiency of 3.93% is achieved for a P3HT:PC71BM blend with 2.4 wt % of TPE-SQ.

Engineering of organic dyes for highly efficient p-type dye-sensitized solar cells

Co-reporter:Fei Wu, Linna Zhu, Shangbi Zhao, Qunliang Song, Chuluo Yang

Dyes and Pigments 2016 Volume 124() pp:93-100

Publication Date(Web):January 2016

DOI:10.1016/j.dyepig.2015.09.008

•Dyes with different spacer length and acceptor groups are synthesized.•The spacer increases the distance from donor group to the semiconductor surface.•Thiobarbituric acid led to broader and stronger absorption in NIR region.•High photocurrent up to 6.735 mA/cm2 was achieved.Four organic dyes, namely T3, T3H, T4 and T4H, are designed and synthesized for p-type photocathodes. Different from the widely explored method of extending conjugation between donor and acceptor, in these dyes, the distance between donor and the semiconductor surface is elongated by three or four alkylated thiophene units. Dicyanovinyl and 1,3-diethyl-2-thiobarbituric acid are introduced as the acceptor units, respectively. It turns out that the increased oligothiophene units between triphenylamine and carboxylate enhances the light harvesting efficiency. Moreover, the thiobarbituric acid offers much broader and stronger absorption reaching the NIR region, thus leading to higher photocurrents in T4H. As a result, dye T4H shows the highest power conversion efficiency of 0.317%, with photocurrent up to 6.735 mA/cm2 using the I−/I3− electrolyte. Notably, the high photocurrent obtained is close to the highest value reported to date for p-type dye-sensitized solar cells (7.57 mA/cm2).

Investigation on a dopant-free hole transport material for perovskite solar cells

Co-reporter:Fei Wu, Baohua Wang, Rui Wang, Yahan Shan, Dingyu Liu, King Young Wong, Tao Chen and Linna Zhu

RSC Advances 2016 vol. 6(Issue 73) pp:69365-69369

Publication Date(Web):18 Jul 2016

DOI:10.1039/C6RA07603C

A tetraphenylethene derivative (TPE-4DPA) was synthesized and applied as the hole transporting material for planar perovskite solar cells. The use of TPE-4DPA for device fabrication requires no oxidization process and lower amount of additives, delivering an overall power conversion efficiency of 12.81%. Remarkably, even in the absence of the additives, the solar cell based on the pristine TPE-4DPA still generates a Jsc as high as 20.50 mA cm−2, and moderate PCE of 9.12%. Using no additives is of critical importance, which simultaneously increases the stability of the devices and reduces the fabrication cost of perovskite solar cells, when compared to devices using Li-TFSI doped Spiro-OMeTAD.

Incorporation of diketopyrrolopyrrole dye to improve photovoltaic performance of P3HT:PC71BM based bulk heterojunction polymer solar cells

Co-reporter:Fei Wu, Yahan Shan, Rui Wang, Linna Zhu

Organic Electronics 2016 Volume 31() pp:171-176

Publication Date(Web):April 2016

DOI:10.1016/j.orgel.2016.01.028

•Diketopyrrolopyrrole based NIR organic dye py-DPP is synthesized.•py-DPP is blended to the P3HT/PC71BM system to get ternary solar cells.•The highest efficiency of 4.05% is achieved with 2.4 wt % of py-DPP.•The efficiency of ternary system shows more than 20% enhancement.Ternary blend solar cells have been intensively studied in recent years to harvest more photons over the near-IR region. In this work, the effects of adding a diketopyrrolopyrrole dye (py-DPP) into a conventional P3HT:PC71BM based bulk heterojunction photovoltaic cell are investigated. The near infrared absorption of the blend is enhanced by the doped py-DPP dye, leading to more than 20% increased power conversion efficiency compared to the P3HT:PC71BM binary system. The highest efficiency of 4.05% is achieved for a P3HT:PC71BM blend with 2.4 wt % of py-DPP.A diketopyrrolopyrrole dye (py-DPP) is incorporated into a conventional P3HT:PC71BM based polymer bulk heterojunction photovoltaic cell. The highest efficiency of 4.05% is achieved for a P3HT:PC71BM blend with 2.4 wt % of py-DPP, corresponding to 20% increase of the power conversion efficiency.

Effect of dimethylamino substituent on tetraphenylethylene-based hole transport material in perovskite solar cells

Co-reporter:Fei Wu, Yahan Shan, Xiaolong Li, Qunliang Song, Linna Zhu

Organic Electronics 2016 Volume 39() pp:323-327

Publication Date(Web):December 2016

DOI:10.1016/j.orgel.2016.10.022

•Dimethylamino substituted tetraphenylethylene was synthesized and characterized.•The tetraphenylethylene derivative was applied as HTM in perovskite solar cells.•The energy levels are well aligned with respect to the perovskite energy level.•Device fabricated using the tetraphenylethylene derivative achieves PCE of 13.78%.A N,N-dimethylamino substituted tetraphenylethylene derivative (TPE-NMe) was synthesized and characterized, and was successfully applied as hole transport material (HTM) in perovskite solar cells. The methoxy-substituted analogue TPE-4DPA was also studied for comparison. The effect of replacing the para-methoxy substituent with N,N-dimethylamino on photophysical properties, energy levels, and hole transport properties is investigated. Photovoltaic performances of the corresponding devices using the two HTMs are studied. Compared to the methoxy substituent, the N,N-dimethylamino groups in TPE-NMe generates a lower Voc (0.87 V), yet it provides higher Jsc (21.69 mA/cm2) and FF (0.73) values, resulting in an overall power conversion efficiency of 13.78%.N,N-dimethylamino substituted tetraphenylethylene derivative (TPE-NMe) was synthesized and characterized, and was successfully applied as hole transport material in perovskite solar cells. Compared with the methoxy substituent, the N,N-dimethylamino substituent provides higher Jsc and FF values.

Revealing a nucleophilic addition reaction between aza-BODIPY and cyanide anion

Co-reporter:Fei Wu, Haitao Liu, Cheng Zhong, Linna Zhu

Tetrahedron Letters 2016 Volume 57(Issue 46) pp:5120-5123

Publication Date(Web):16 November 2016

DOI:10.1016/j.tetlet.2016.10.024

•The precise reaction position between aza-BODIPY and CN− is investigated.•CN− is verified to attack the pyrrole unit of the boron-dipyrromethene construct.•Single crystal structure could well support the proposed reaction mechanism.•The reaction causes significant photophysical changes of aza-BODIPY.In this work, a new nucleophilic addition reaction between the aza-BODIPY construct and cyanide anion is investigated and confirmed. Interestingly, CN− is verified to attack one of the pyrrole rings on the boron-dipyrromethene construct, which is different from the present CN− detection systems. The reaction mechanism is proposed based on NMR results and the photophysical spectra changes. In addition, when the electron-rich substituents are introduced to the aza-BODIPY structure, the reaction with CN− will become slow, thus confirming the nucleophilic addition reaction nature. More importantly, the mass spectra and single crystal structure of the aza-BODIPY-CN adduct could well support the proposed reaction mechanism. The reaction between CN− and aza-BODIPY is very fast (in 5 min at room temperature) and results in significant absorption and emission changes of the aza-BODIPY compound. This work, as far as we know, is the first attempt to systematically reveal the reaction between CN− and the aza-BODIPY compound.Cyanide anions attack one of the pyrrole rings of the boron-dipyrromethene skeleton, yielding significant color changes and NIR fluorescence quench of the aza-BODIPY.

Phenothiazine-cyanine-functionalized upconversion nanoparticles for LRET and colorimetric sensing of cyanide ions in water samples

Co-reporter:Shangbi Zhao, Fei Wu, Yanan Zhao, Yingshuai Liu, Linna Zhu

Journal of Photochemistry and Photobiology A: Chemistry 2016 s 319–320() pp: 53-61

Publication Date(Web):15 March 2016

DOI:10.1016/j.jphotochem.2015.12.022

•Phenothiazine-cyanine-functionalized upconversion nanoparticles are devised.•The probe utilizes upconverting luminescence to detect cyanide ions.•The detection limit is much lower than the record from a similar platform.•The platform could detect cyanide ions with high sensitivity and selectivity.•The cyanide probe is able to work well in real water samples.Upconversion nanoparticles (UCNPs) could serve as an excellent signaling unit for sensing due to their advantages such as near-infrared excitation, no autofluorescence, low damage to samples and no photobleaching. In this work, a detection platform comprising UCNPs modified with phenothiazine-cyanine (PTZCy) is achieved for efficient cyanide detection based on the luminescent resonance energy transfer (LRET) process. The UCNPs is modified with γ-cyclodextrin (γ-CD) to increase the solubility in water and meanwhile to generate a hydrophobic cavity for PTZCy and realize detection of CN− in pure water. PTZCy has a significant absorbance with a maximum at 542 nm, which ideally overlaps the emission band of UCNPs at around 540 nm and results in a LRET process to quench the green emission. After addition of CN−, the absorbance intensity of PTZCy at 542 nm decreases dramatically, and the LRET process is terminated and the green emission from UCNPs will be recovered, concurrently, the solution color of PTZC-UCNPs changes from light purple to colorless. This upconverting luminescence recognition of cyanide ions could be finished as soon as the CN− is added, while all the other anions have no influence on the detection process. The detection limit (0.84 μM) is much lower than the reported value obtained from a UCNP-Ir complex based probe (37.6 μM). In addition, the CDs could protect the organic dyes from photobleaching and photodegradation. The results indicate that the cyanide probe in this work is superior when compared with the other UCNPs based cyanide probes. This newly developed sensor allows efficient sensing of CN− in pure water, moreover, it also works well in real water samples taken from underground water or a lake.

Monolayer molecular probes for detection of trace amounts of cyanide anions

Co-reporter:Fei Wu, Shangbi Zhao and Linna Zhu

RSC Advances 2015 vol. 5(Issue 128) pp:106191-106196

Publication Date(Web):01 Dec 2015

DOI:10.1039/C5RA21989B

In this work, monolayer sensor molecules are firstly developed for the detection of trace amounts of cyanide ions in aqueous solution, which was inspired by the fact that in dye-sensitized solar cells, dye molecules adsorb onto the semiconductor surface by forming a monolayer. Compound P1 is a well-known p-type dye molecule in dye-sensitized solar cells, with a carboxyl group on the triphenylamine used as the anchoring point. Thus it could be adsorbed onto a metal oxide (such as TiO2 and NiO) surface to form a monolayer M-P1. M-P1 detects cyanide through a nucleophilic addition reaction between the negatively charged CN− and the dicyanovinyl group, resulting in a weaker intramolecular charge transfer from the donor to acceptor in P1. The detection behavior could be easily observed from a visual color change of the metal oxide films, which was also in agreement with their UV-vis absorption spectral changes. Since the adsorbed sensor molecules are in very small amounts (at the nM level), M-P1 could be applied to detect trace amounts of CN− in aqueous solution (pH = 7.4) with high sensitivity, selectivity and anti-interference ability. The detection limit of the monolayer sensor is determined to be 2.99 nM, which is far below the WHO cyanide standard for drinking water (1.9 μM). Additionally, it is much lower than that obtained by dissolving P1 and the analytes in organic solution. The results demonstrate that the monolayer sensor has high sensitivity and selectivity, and is very efficient for detecting trace amounts of analytes in dilute solution, and the detection could be easily observed by the naked eye. Moreover, the idea of a monolayer sensor excludes the requirement of an organic environment for reaction-based sensors to function, and provides new possibilities for constructing probes in the future.

Insights into dye design for efficient p-type photoelectrodes: effect of oligothiophene length between the donor and the NiO surface

Co-reporter:Fei Wu, Shangbi Zhao, Cheng Zhong, Qunliang Song and Linna Zhu

RSC Advances 2015 vol. 5(Issue 113) pp:93652-93658

Publication Date(Web):27 Oct 2015

DOI:10.1039/C5RA19854B

We report experimental studies of “push–pull” organic dyes with three to six thiophene units as π-spacers, and their application as p-type sensitizers for dye-sensitized solar cells. Different from the widely explored model of increasing spacer length between donor and acceptor, in this paper, the distance between the donor and the semiconductor surface is elongated by inserting thiophene units. The effect of the increased π-spacer is systematically discussed. It turned out that four thiophene units could offer T4 with the highest performance. Further increased length instead, results in decreased Jsc values and finally decreased efficiencies. We estimate that the longer spacer could effectively prevent charge recombination on the NiO-dye surface, however, the increased thiophene units also decrease the conductance of the oligothiophene spacer, which is unfavorable for hole injection from dye molecule to the valence band of NiO. The results demonstrate that the distance between donor and the semiconductor should be optimized. The appropriate length is required to balance charge recombination and charge transporting efficiency.

DAA-Type Organic Dyes for NiO-Based Dye-Sensitized Solar Cells

Co-reporter:Fei Wu;Jianlin Liu;Xi Li;Qunliang Song;Min Wang;Cheng Zhong

European Journal of Organic Chemistry 2015 Volume 2015( Issue 31) pp:6850-6857

Publication Date(Web):

DOI:10.1002/ejoc.201501036

Abstract

Three new D–A–A-type organic sensitizers – W1, W2, and W3 – have been synthesized and applied for p-type dye-sensitized solar cells. For the first time, the electron-withdrawing 2,1,3-benzothiadiazole (BT) unit has been applied as the π-bridge between the triphenylamine donor and different acceptors in these dye molecules. It turns out that these dyes all exhibit power conversion efficiencies exceeding 0.1 %, and that the best performance is achieved by the dye W2, with an octyl 2-cyanoacrylate acceptor. It shows a power conversion efficiency of 0.166 %, with a short circuit current of 4.16 mA cm^–2 and an open circuit voltage of 0.121 V. The higher light-harvesting efficiency leads to a higher photocurrent in W2. In addition, electrochemical impedance spectroscopy (EIS) studies suggest slower charge recombination at the metal oxide/electrolyte interface and a faster hole-transporting ability of W2. The factors together may account for the higher power conversion efficiency of W2. This work demonstrates rational design of these dye molecules for the construction of efficient p-type sensitizers.

Novel organic dyes based on diarylmethylene-bridged triphenylamine for dye-sensitized solar cells

Co-reporter:Fei Wu, Lawrence Tien Lin Lee, Jianlin Liu, Shangbi Zhao, Tao Chen, Min Wang, Cheng Zhong, Linna Zhu

Synthetic Metals 2015 Volume 205() pp:70-77

Publication Date(Web):July 2015

DOI:10.1016/j.synthmet.2015.03.033

•Organic dyes containing diarylmethylene-bridged triphenylamine are synthesized.•The hexyl substituted thiophene attached are advantageous for light harvesting.•Dye TTB-1 provides the highest power conversion efficiency of 4.35 %.Three D–π–A type organic dyes, including TB-1, TTB-1 and TTB-2, which contained bridged triphenylamine (TPA) donor moieties, were synthesized and characterized for applications in dye-sensitized solar cells (DSSCs). Compared to TB-1, the 5-hexyl and 3-hexyl substituted thiophene rings were introduced onto the TPA core in TTB-1 and TTB-2. Their photophysical, electrochemical and photovoltaic properties were investigated. The reference compound L1 (the triphenylamine counterpart of TB-1) was also evaluated for comparison. Compared to L1, the bridged triphenylamine based dyes studied showed enhanced performances, suggesting reasonable design of the new dyes. Meanwhile, the investigation of the three bridged TPA dyes demonstrated that by grafting 5-hexyl substituted thiophene onto the bridged TPA, TTB-1 had a significantly broader absorption spectrum in the UV–vis region, and thereby, its light harvesting ability was remarkably enhanced. Accordingly, the higher incident photon to current conversion efficiency (IPCE) of TTB-1 indicated a higher short-circuit current. In contrast, the 3-hexyl substituted thiophene in TTB-2 lead to larger steric hindrance, resulting in lower Jsc value. Similar structure of TTB-1 and TTB-2 afforded almost the same Voc. Therefore, dye TTB-1 showed the best performance, exhibiting power conversion efficiency of 4.35%, with Jsc of 8.61 mA cm−2 and Voc of 704 mV under simulated AM 1.5 irradiation (100 mW cm−2).

New Organic Dyes Based on Biarylmethylene-Bridged Triphenylamine for Dye Sensitized Solar Cell

Co-reporter:Fei Wu;Haitao Liu;Lawrence Tien Lin Lee;Tao Chen;Min Wang

Chinese Journal of Chemistry 2015 Volume 33( Issue 8) pp:925-933

Publication Date(Web):

DOI:10.1002/cjoc.201500137

Abstract

Three new organic dyes were synthesized and characterized for applications in dye-sensitized solar cells (DSSCs). In these dyes, diarylmethylene-bridged triphenylamine is the donor, and different acceptors and vinylthiophene are designed to get TBA-1, TBA-2 and TBA-3. Their photophysical, electrochemical and photovoltaic properties were investigated, and the effects of the acceptor structures as well as the linkage on these properties were evaluated. Results demonstrated that the vinylthiophene linkage between the donor and the acceptor is favorable for improving light harvesting ability of TBA-2. In addition, the electrochemical impedance spectroscopy experiments suggest larger R_rec and longer electron lifetime of TBA-2. Therefore, it outperforms the other dyes, exhibiting the highest power conversion efficiency of 3.87%, with J_sc of 8.25 mA·cm⁻² and V_oc of 666 mV. Unfortunately, the TBA-3 with three acceptor groups only shows efficiency of 3.52%, indicating that the design of increasing acceptor groups plays little role on enhancing the solar cell efficiency.

Novel D-π-A organic sensitizers containing diarylmethylene-bridged triphenylamine and different spacers for solar cell application

Co-reporter:Fei Wu, Shangbi Zhao, Lawrence Tien Lin Lee, Min Wang, Tao Chen, Linna Zhu

Tetrahedron Letters 2015 Volume 56(Issue 10) pp:1233-1238

Publication Date(Web):4 March 2015

DOI:10.1016/j.tetlet.2015.01.156

Bridged triphenylamine having almost planar core structure is a potential donor moiety for DSSCs. In this work, three novel D-π-A organic dyes TB-1, TB-2, and TB-3, containing diarylmethylene-bridged triphenylamine as the donor moiety, cyanoacrylic acid as the acceptor, and thiophene, benzene or furan as the π-spacers were synthesized and characterized for applications in dye-sensitized solar cells (DSSCs). Their photophysical, electrochemical, and photovoltaic properties were investigated, the performance of the triphenylamine donor was compared, and the effect of different π-spacers was evaluated. Results demonstrated that compared to the nonplanar triphenylamine donor, the more planar bridged TPA could offer better charge transfer process and as a result higher performances. On the other hand, in these compounds, both thiophene and furan linkages show better planarization and electron delocalization compared to the benzene linkage in this molecular system. Accordingly, dye TB-1 and TB-3 show higher IPCE and Jsc values. Considering the larger Voc of dye TB-3, therefore it outperforms the other two sensitizers, exhibiting power conversion efficiency of 3.81%, with Jsc of 7.54 mA cm−2 and Voc of 725 mV under simulated AM 1.5 irradiation (100 mW cm−2). The results are further confirmed by the EIS experiments.Three novel D-π-A organic dyes containing diarylmethylene-bridged triphenylamine as the donor moiety, cyanoacrylic acid as the acceptor, and thiophene, benzene or furan as the π-spacers were synthesized. Dyes with furan and thiophene linkages show better planarization and electron delocalization compared to the benzene linkage. The furan unit as π-spacer provides the highest power conversion efficiency of 3.81%.

Dye-sensitized solar cells based on functionalized truxene structure

Co-reporter:Fei Wu, Jian-Lin Liu, Lawrence Tien Lin Lee, Tao Chen, Min Wang, Lin-Na Zhu

Chinese Chemical Letters 2015 Volume 26(Issue 8) pp:955-962

Publication Date(Web):August 2015

DOI:10.1016/j.cclet.2015.03.008

Three new metal-free organic dyes (TX1, TX2 and TX3) based on truxene core structure, with triphenylamine as the electron donor, thiophene as the π spacers, and cyanoacetic acid or rhodanine-3-acetic acid as the electron acceptor are designed and synthesized. Their UV–vis absorption spectra, electrochemical and photovoltaic properties were investigated. The cyanoacrylic acid is verified to be a better acceptor unit (meanwhile the anchoring group) compared to the rhodanine-3-acetic acid. And also, two anchoring groups in TX2 could provide stronger adsorption ability on the TiO2 surface. In addition, the EIS results indicate a slower charge recombination processes for TX2. As a result, dye TX2 bearing two cyanoacetic acid outperforms the other two dyes, exhibiting the photo-conversion efficiency of 2.64%, with Jsc = 5.09 mA cm–2, Voc = 729 mV, FF = 71.1.Three new truxene based organic dyes (named TX1, TX2 and TX3) are synthesized and their photovoltaic properties were investigated. Dye TX2 bearing two cyanoacetic acid parts exhibited the highest photo-conversion efficiency of 2.64%.

Fluorine-substituted benzothiadiazole-based hole transport materials for highly efficient planar perovskite solar cells with a FF exceeding 80%

Co-reporter:Fei Wu, Yu Ji, Cheng Zhong, Yuan Liu, Luxi Tan and Linna Zhu

Chemical Communications 2017 - vol. 53(Issue 62) pp:NaN8722-8722

Publication Date(Web):2017/07/11

DOI:10.1039/C7CC04606E