•Star-shaped Z1012 and Z1013 were applied in perovskite solar cell as HTMs.•Photovoltaic cells based on Z1013 without dopants achieve an excellent PCE of 15.4%.•The devices based on these two HTMs show better stability when aging in ambient air.Two star-shaped TPA-based small-molecule materials (Z1012 and Z1013) were designed and synthesized in this paper. These molecules show high hole mobility and suitable energy levels for CH3NH3PbI3-based perovskite solar cells. Photovoltaic cells based on the Z1013 without any dopants or additives achieve an excellent power conversion efficiency (PCE) of 15.4%, which is comparable to devices based on state-of-art p-doped spiro-OMeTAD. Moreover, the devices based on these two HTMs show much better stability than that of devices based on spiro-OMeTAD when aging in ambient air both at room temperature and 80 °C. These results demonstrate that star-shape TPAs could be excellent dopant-free HTMs for perovskite solar cells and hold promise to replace the p-doped spiro-OMeTAD, which is important for the fabrication of cost-effective and stable devices.Two star-shaped triphenylamine (TPA) based small-molecules were synthesized and used as dopant-free hole-transport materials for efficient perovskite solar cells.Figure optionsDownload full-size imageDownload as PowerPoint slide

Here, we report a rapid and simple process to prepare perovskite solar cells in ambient air by adding 2-pyridylthiourea in the precursor solution. 2-Pyridylthiourea can not only promote the conversion of 2-D PbI2 to tetragonal CH3NH3PbI3 crystals, but also improve the quality of the perovskite absorber layer via enhancing the uniformity and the size of the crystal grains. The perovskite solar cells with the addition of 2-pyridylthiourea at a concentration of 0.5 mg mL−1 exhibited a remarkable overall power conversion efficiency (PCE) of 18.2%, which is among the highest PCE of CH3NH3PbI3-based devices fabricated in ambient air. It also showed an 18% increase and less hysteresis compared with the cells without additives. Importantly, the devices with 2-pyridylthiourea show relatively better stability compared to reference devices when aged under ambient air of 55 ± 5% relative humidity in the dark and under 65 °C after 30 days. The presented results clearly show that 2-pyridylthiourea can be an additive candidate for tuning the morphology of perovskite thin films, which may be a new direction for large-scale production of PSCs.

The self-doping CH3NH3PbBr3 crystals were fabricated by modulating the molar ratio of PbBr2 to CH3NH3Br from 0.2 to 1.5 to afford p- and n-type materials. The effect of modulating the inorganic to organic content on crystal framework, optical properties, energy level, conductivity, carrier mobility and concentration of CH3NH3PbBr3 crystals were studied by X-ray diffraction (XRD), photoluminescence (PL), photoelectron yield spectroscopy (PYS), Hall-effect measurement and X-ray photoelectric spectroscopy (XPS). It is found that different precursor ratio results in different surface and bulk element composition of the CH3NH3PbBr3 crystals, which influences the intrinsic defects hence the conductivity of perovskite crystals. Low precursor ratios (Pb-poor/Br-rich growth conditions) gave p-doped crystals and vice versa, which is governed by the dominant intrinsic defects of crystals. In addition, the O in the surface composition was much higher than that inside of the crystals, indicating that the crystal surfaces were doped with O to form extrinsic defects.

A fullerene derivative (α-bis-PCBM) is purified from an as-produced bis-phenyl-C61-butyric acid methyl ester (bis-[60]PCBM) isomer mixture by preparative peak-recycling, high-performance liquid chromatography, and is employed as a templating agent for solution processing of metal halide perovskite films via an antisolvent method. The resulting α-bis-PCBM-containing perovskite solar cells achieve better stability, efficiency, and reproducibility when compared with analogous cells containing PCBM. α-bis-PCBM fills the vacancies and grain boundaries of the perovskite film, enhancing the crystallization of perovskites and addressing the issue of slow electron extraction. In addition, α-bis-PCBM resists the ingression of moisture and passivates voids or pinholes generated in the hole-transporting layer. As a result, a power conversion efficiency (PCE) of 20.8% is obtained, compared with 19.9% by PCBM, and is accompanied by excellent stability under heat and simulated sunlight. The PCE of unsealed devices dropped by less than 10% in ambient air (40% RH) after 44 d at 65 °C, and by 4% after 600 h under continuous full-sun illumination and maximum power point tracking, respectively.

In this study, in order to serve as black particles for electrophoretic displays (EPDs), copper chromite black (CCB) particles were successfully endowed with particle charge in nonpolar Isopar L in the presence of nonionic surfactants (Span80, Span85 and polyisobutylene-mono-succinimide (T151)). Initially, the CCB particles were coated with silica (CCB/SiO2) to gain surface active spots. By measuring their electrophoretic mobility in Isopar L, it is found that all the samples possess a negative charge with a maximum of −12.95 × 10−10, −14.18 × 10−10 and −17.43 × 10−10 m2 V−1 s−1 at 12, 16 and 16 mM for Span80, Span85 and T151, respectively. Moreover, the particle charge values of the surfactant treated CCB/SiO2 particles were ordered as T151 > Span85 > Span80. These charging behaviors were discussed and interpreted from the point of charged micelles via measuring the conductivity and transient current of corresponding surfactant solutions. Significantly, a prototype EPD employing T151 treated CCB particles exhibited a quite quick response (response time: 189.6 ms) with a white–black contrast ratio of 6.27 under 0.3 V μm−1. This excellent display performance renders the CCB particles to be a promising pigment for producing the black color in electronic paper and other display applications.

•Fluorination had a profound influence on the structure of molecules and crystals.•Fluorination enhanced solvent resistance and decreased fastness to light and heat in both cases.•Fluorinated pigments exhibited irregular and smaller crystals compared to its analogues.The synthesis and single crystal X-ray structures of two fluorinated azo pigments and their nonfluorinated analogues derived from N-acetoacetanilide and N,N′-(1,4-phenylene) bis-(acetoacetamide) as coupling components were described. These two kinds of pigments existed in the ketohydrazone and bisketohydrazone tautomeric form with intramolecular hydrogen bondings respectively. Fluorination had a profound influence on the structure of molecules and crystals and consequently altered the morphology and pigmentary performance. The results demonstrated that the solvent resistance was improved upon fluorination due to enhanced intermolecular interactions and efficient π-packing of molecules. However, in both cases fluorination gave rise to pigments with poorer stability to heat and light.

•Reported a new deep blue emitter with high quantum yield and good thermal stability.•The emitter shows good bipolar transporting characteristics.•The non-doped OLED exhibits high current and power efficiency (2.30 cd/A, 1.52 lm/W).A deep blue emitting compound 9-(4′-(1,4,5-triphenyl-1H-imidazol-2-yl)-[1,1′-biphenyl] -4-yl)-9H-carbazole was designed and synthesized. The emitting compound characters as donor-π-acceptor structure with carbazole as the electron-donor and imidazole as the electron-acceptor. The emitting compound shows high quantum yield (0.87) in solution and good thermal stability. The emitting compound exhibits bipolar transporting characteristics identified by single-carrier devices. The non-doped fluorescent organic light-emitting diode with the emitting compound as emitting layer exhibits emission peak at 420 nm and full width at half maximum of 54 nm, maximum current efficiency of 2.30 cd/A, and maximum power efficiency of 1.52 lm/W, which are higher than most reported deep blue emitters with a y coordinate ≤0.064. The chromaticity coordinate is stable at (0.166, 0.064) with increasing operation voltage.The structure of device and EL spectra and CIE diagram at different voltages.

•A layered thiocyanate-modified organometal perovskite material was prepared.•Single crystal was acquired firstly in emerging SCN−-substituted perovskite.•The material shows great solubility and crystallinity in low boiling-point solvent.•3.32% PCE and as much as 0.725 FF of the solar cell device was achieved.•Excellent film morphology can be achieved without thermal annealing.A novel layered organometal halide perovskite material (CH3NH3)2Pb(SCN)2I2 was acquired by replacing the iodide ions locating on the axial positions of CH3NH3PbI3 octahedron with thiocyanide anions. The molecular structure of this material was characterized by X-ray single crystal diffraction, through which the thiocyanides were proved to be coordinated as terminal ligands on the lead center. A variety of spectral tests reveal material’s energy gap (Eg) and valence band (VB) as 1.65 eV and −5.76 eV, respectively. The concentration of holes has also been located as up to 1.07 × 1014 cm−3 via Hall effect measurement. What is important, for the material shows great solubility and crystallinity in low boiling-point solvent tetrahydrofuran, excellent film morphology can be achieved via a convenient and practical one-step precursor solution-deposition method without thermal annealing. The fill factor (FF) of solar cell devices based on this material can be promoted as much as 0.725.

•The effects of CHENO as a coadsorbent and the solvent on the solar cell’s performance were investigated..•Adding CHENO onto TiO2 not only reduced the adsorption of Pc sensitizers but also prevented the aggregation behavior..•It indicated that CuPc-Cou in DMF was easy to aggregate than in CH2Cl2 for the solvent effect..The synthesis, characterization and thermal properties of CuPc-Cou were reported and the effects of chenodeoxycholic acid (CHENO) as a coadsorbent and the solvent on the solar cell's performance were investigated. The ground state absorbance of CuPc-Cou showed the molar extinction coefficients as high as 2.90 × 104 dm3 mol−1 cm−1 in DMF and 2.74 × 104 dm3 mol−1 cm−1 in CH2Cl2. The thermal stability studies indicated that CuPc-Cou was stable up to 370 °C. Furthermore, HOMO and LUMO energies made it clear that CuPc-Cou can be used as a sensitizer for DSSC. Adding CHENO onto TiO2 nanoparticles not only reduced the adsorption of phthalocyanine sensitizers but also prevented the aggregation behavior, leading to different photovoltaic performance. The open circuit voltage of the solar cells with CHENO coadsorbent increased due to the enhanced electron lifetime in TiO2 nanoparticles coupled with the band edge shift of TiO2 to negative potentials. The optimal dye adsorption condition of the TiO2 electrode was found to be 3 × 10−4 M CuPc-Cou solution containing 6.0 mM CHENO in dichloromethane, which could contribute to improve the PCE by 69% as compared to the solar cell fabricated with TiO2 electrode sensitized by the CuPc-Cou in absence of CHENO and the optimal condition in DMF. It indicated that CuPc-Cou in DMF was easy to aggregate than in CH2Cl2 for the solvent effect.

A series of novel triphenylamine-based small molecular hole transport materials (HTMs) are reported for solution processed organic light-emitting devices (OLEDs). The character of this series of HTMs, denoted as TPD(BTPA)n (n = 1, 2, 4), is connecting the flexible moieties of butadiene bridged triphenylamine (BTPA) to N,N,N′,N′-tetraphenyl-[1,1′-biphenyl]-4,4′-diamine (TPD). The glass transition temperature and crystallization temperature (Tg and Tc) showed a proportional relationship with the number of BTPA moieties. The Tg value of TPD(BTPA)4 can be up to 125.5 °C, which is higher than most of the reported small molecular HTMs (Tg: 54–116 °C). The TPD(BTPA)4 spincoated film showed an outstanding thermal stability which remained amorphous even when annealed at 110 °C, for 48 h. This indicated that the breaking of the planar molecular structure with BTPA moieties can suppress intermolecular stacking. The solution processed OLEDs with 8-hydroxyquinoline aluminum (Alq3) as emission and electron transport layers showed high stability at high operation current (>400 mA cm−2). The OLED with TPD(BTPA)4 achieved a maximum current efficiency of 5.83 cd A−1 (at the operation current density > 400 mA cm−2), which is higher than the maximum current efficiency of most evaporation and solution processed OLEDs in identical structures.

Poly(3,4-ethylenedioxythiophene) (PEDOT) is a kind of conductive polymer. PEDOT doped with polystyrolsulfon acid (PSS) is often used as an interface material of microelectrode to improve the electrochemical characteristic. Due to unsymmetrical oxidation and reduction, the properties of PEDOT:PSS need to be improved furtherly. We use Sodium Dodecyl Sulfate (SDS) instead of PSS to dope PEDOT. Electrolytic deposition method is used to modify PEDOT:SDS on the surface of plane gold micro-electrodes fabricated with MEMS process. Compared with PEDOT:PSS, there are significant improvements in the electrochemical performance and anti-aging ability of the PEDOT:SDS modified microelectrode. The impedance of the electrode modified with PEDOT:SDS is nearly half of the impedance of PEDOT:PSS. As for the anti-aging ability, the electrical stability of SDS doped PEDOT is 3.5 times longer than the electrical stability of PSS.

Six novel photochromic and electrochromic diarylethenes containing triphenylamine units were synthesized by the McMurry reaction. The properties of photochromism, electrochromism, fluorescence and electrochemistry were investigated in detail. The results showed that these compounds exhibited reversible photochromism, changing from colorless to yellow after irradiation with 302 nm UV light both in solution and in PMMA amorphous film. When arriving at the photostationary state, the fluorescent intensity was quenched to about 40%. In the cyclic voltammetry curves, there were a reversible redox couple and one or two irreversible oxidation peaks. The potential of the reversible oxidation peak is adopted as the excitation voltage of electrochromism. The electrochromic devices could be simulated with an equivalent circuit, R(CR)(CR), by electrochemical impedance spectroscopy, and the transformation between colorless and blue was realized, which required 8.6 to 12.1 s for color switching and 8.9 to 12.8 s for bleaching. The reflectance minima of these compounds are in the range from 709.7 to 781.7 nm after coloring. The results showed that diarylethenes containing triphenylamine units possessed both photochromic and electrochromic properties.

This work reports the synthesis of 7-hydroxy-4-methylcoumarin tetrasubstituted Ruthenium (III)(4a), Indium (III)(4b), Tin (IV)(4c) phthalocyanines bearing axial chloride ligand for the first time. These new metallophthalocyanines show good solubility in many organic solvents. This study also investigates the photophysical (fluorescence quantum yield and lifetime) properties of compounds 4a, 4b and 4c. The fluorescence of these three metallophthalocyanines is effectively quenched by the addition of 1,4-benzoquinone (BQ). The thermal stability studies indicate that both 4a and 4b are stable up to 300 °C.The synthesis, photophysical (fluorescence quantum yields and lifetimes) and thermal properties of 7-hydroxy-4-methylcoumarin tetrasubstituted Ruthenium (III), Indium (III) and Tin (IV) phthalocyanine complexes with axial chloride ligand are described. The fluorescence of these three metallophthalocyanines is effectively quenched by the addition of 1,4-benzoquinone (BQ). The thermal stability studies indicate that both 4a and 4b are stable up to 300 °C.Highlights► Novel RuIII, InIII, SnIV phthalocyanines with axial chloride ligand were synthesized. ► Fluorescence quantum yields and fluorescence lifetime were measured. ► RuIII and InIII phthalocyanines showed high thermal stabilities.

In this paper, we reported an effective approach for fabrication of hollow TiO2 as electrophoretic particles. In this approach, the copolymer was first synthesized via emulsifier-free emulsion polymerization using the cationic initiator. Subsequently, the core-shell structure was successfully formed by deposited titanium dioxide and calcination resulted in spherical shells composed of a dense arrangement. The whole process didn't require any surfactant or surface modification. The result showed that high efficiency hollow TiO2 nanospheres were obtained with the average diameter of approximately 230 nm. Furthermore, we investigated freeze drying process of core-shell structure; this kind of process could effectively reduce the fragmentation and break during the calcination. To the best of our knowledge, using freeze drying process to prevent breaking the hollow spheres was seldom mentioned in related paper. Without extra surface modification, low density hollow TiO2 nanoparticles were dispersed into medium then filled into micro-cup device. The obtained high efficiency hollow TiO2 nanospheres were fit for electronic paper display at low voltage.Highlights► An effective approach for fabrication of hollow TiO2. ► Freeze drying of core-shell effectively reduce the fragmentation and break. ► The obtained low density hollow TiO2 nanoparticles dispersed into medium, filled into micro-cup device. ► High efficiency hollow TiO2 nanospheres can display at low voltage.

Two novel organic hole-transporting materials have been synthesized by combination of triphenylamines (TPA) via π-conjugated bonds using Wittig reaction. The structures were characterized by NMR, FT-IR and HRMS. The optical, electrochemical and thermal properties of the materials were studied in detail. The results show that these two compounds have blue emission, proper HOMO levels and high thermal stability. Furthermore, a quantum chemical calculation on electron distribution of the two compounds was performed, which suggests the current synthesized materials would be promising candidates for hole-transporting materials.

Hollow TiOX nanospheres have been successfully prepared using hollow core–double shell latex particles (poly(styrene-co-methyl methacrylate-co-butyl acrylate-co-methacrylic acid) (abbreviated in poly(St-co-MMA-co-BA-co-MAA)) as template, which involves the deposition of inorganic coating on the surface of hollow core–shell latex particles and subsequent removal of the latex by calcinations in air or ammonia gas. Ti(OBu)4 was used as precursor for the preparation of hollow TiOX nanospheres. TEM of white hollow core–double shell polymers particles with an aperture of approximately 225 nm displays the perfect characteristic hollow nanospheres structure of primary core–double shell particles. The formation of TiOX was confirmed by XRD analysis and hollow structure of the particles was revealed by transmission electron microscopy (TEM). When the calcined temperature was at 800 °C, hollow TiO2 nanospheres were arranged regularly with the diameter range of 130–170 nm. The electrophoretic properties were characterized by JS94J micro-electrophoresis apparatus. The electrophoretic mobility of white TiO2 and black TiO hollow spheres in tetrachloroethylene were 1.09 × 10−5 and 3.12 × 10−5 cm2/V s, and the zeta potentials were 7.10 and 20.24 mV, respectively. The results show that white TiO2 particles and black TiO hollow nanoparticles are suitable as electrophoretic particles and possess the application potential in the future electrophoretic display.

Six bisazo compounds were synthesized by coupling 2-(4′-aminophenyl)-6-aminobenzoxazole as diazo component with N-phenyl-N′-(2-hydroxy-3-naphthoyl)urea derivatives, and characterized by ultra-violet and visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR) and elemental analysis (EA). Using these bisazo compounds as charge generation materials and CT-191(2-methyl-4-(N,N-dibenzyl) aminobenzoaldehyde-1,1-diphenylhydrazone) as charge transportation material, organic photoconductive devices were prepared. The result from photoconductivity measurement of the devices shows that the bisazo compound from N-(2-methylphenyl)-N′-(2-hydroxy-3-naphthoyl)urea has the best xerographic performance, V0=600 V, VR=30 V, Rd=15 V·s−1, E1/2=3.5 lx·s.

A hole transport material ST1 was synthesized by a one-step Heck reaction. Compared to Spiro-OMeTAD, perovskite solar cells with ST1 exhibit a remarkable overall power conversion efficiency of 15.4% without the use of any dopants and additives, which is comparable to that of the devices based on doped Spiro-OMeTAD (16.3%) and present better stability during a four week aging test.

Here, we report a rapid and simple process to prepare perovskite solar cells in ambient air by adding 2-pyridylthiourea in the precursor solution. 2-Pyridylthiourea can not only promote the conversion of 2-D PbI2 to tetragonal CH3NH3PbI3 crystals, but also improve the quality of the perovskite absorber layer via enhancing the uniformity and the size of the crystal grains. The perovskite solar cells with the addition of 2-pyridylthiourea at a concentration of 0.5 mg mL−1 exhibited a remarkable overall power conversion efficiency (PCE) of 18.2%, which is among the highest PCE of CH3NH3PbI3-based devices fabricated in ambient air. It also showed an 18% increase and less hysteresis compared with the cells without additives. Importantly, the devices with 2-pyridylthiourea show relatively better stability compared to reference devices when aged under ambient air of 55 ± 5% relative humidity in the dark and under 65 °C after 30 days. The presented results clearly show that 2-pyridylthiourea can be an additive candidate for tuning the morphology of perovskite thin films, which may be a new direction for large-scale production of PSCs.

A series of novel triphenylamine-based small molecular hole transport materials (HTMs) are reported for solution processed organic light-emitting devices (OLEDs). The character of this series of HTMs, denoted as TPD(BTPA)n (n = 1, 2, 4), is connecting the flexible moieties of butadiene bridged triphenylamine (BTPA) to N,N,N′,N′-tetraphenyl-[1,1′-biphenyl]-4,4′-diamine (TPD). The glass transition temperature and crystallization temperature (Tg and Tc) showed a proportional relationship with the number of BTPA moieties. The Tg value of TPD(BTPA)4 can be up to 125.5 °C, which is higher than most of the reported small molecular HTMs (Tg: 54–116 °C). The TPD(BTPA)4 spincoated film showed an outstanding thermal stability which remained amorphous even when annealed at 110 °C, for 48 h. This indicated that the breaking of the planar molecular structure with BTPA moieties can suppress intermolecular stacking. The solution processed OLEDs with 8-hydroxyquinoline aluminum (Alq3) as emission and electron transport layers showed high stability at high operation current (>400 mA cm−2). The OLED with TPD(BTPA)4 achieved a maximum current efficiency of 5.83 cd A−1 (at the operation current density > 400 mA cm−2), which is higher than the maximum current efficiency of most evaporation and solution processed OLEDs in identical structures.

In this study, in order to serve as black particles for electrophoretic displays (EPDs), copper chromite black (CCB) particles were successfully endowed with particle charge in nonpolar Isopar L in the presence of nonionic surfactants (Span80, Span85 and polyisobutylene-mono-succinimide (T151)). Initially, the CCB particles were coated with silica (CCB/SiO2) to gain surface active spots. By measuring their electrophoretic mobility in Isopar L, it is found that all the samples possess a negative charge with a maximum of −12.95 × 10−10, −14.18 × 10−10 and −17.43 × 10−10 m2 V−1 s−1 at 12, 16 and 16 mM for Span80, Span85 and T151, respectively. Moreover, the particle charge values of the surfactant treated CCB/SiO2 particles were ordered as T151 > Span85 > Span80. These charging behaviors were discussed and interpreted from the point of charged micelles via measuring the conductivity and transient current of corresponding surfactant solutions. Significantly, a prototype EPD employing T151 treated CCB particles exhibited a quite quick response (response time: 189.6 ms) with a white–black contrast ratio of 6.27 under 0.3 V μm−1. This excellent display performance renders the CCB particles to be a promising pigment for producing the black color in electronic paper and other display applications.