Recently, CuSbS 2 has been proposed as an alternative earth-abundant absorber material for thin film solar cells. However, no systematic study on the chemical, optical, and electrical properties of CuSbS 2 has been reported. Using density functional theory (DFT) calculations, we showed that CuSbS 2 has superior defect physics with extremely low concentration of recombination-center defects within the forbidden gap, espeically under the S rich condition. It has intrinsically p-type conductivity, which is determined by the dominant Cu vacancy (V Cu ) defects with the a shallow ionization level and the lowest formation energy. Using a hydrazine based solution process, phase-pure, highly crystalline CuSbS 2 film with large grain size was successfully obtained. Optical absorption investigation revealed that our CuSbS 2 has a direct band gap of 1.4 eV. Ultraviolet photoelectron spectroscopy (UPS) study showed that the conduction band and valence band are located at 3.85 eV and −5.25 eV relative to the vacuum level, respectively. As the calculations predicted, a p-type conductivity is observed in the Hall effect measurements with a hole concentration of ∼10 18 cm −3 and hole mobility of 49 cm 2 /(V s). Finally, we have built a prototype FTO/CuSbS 2 /CdS/ZnO/ZnO:Al/Au solar cell and achieved 0.50% solar conversion efficiency. Our theoretical and experimental investigation confirmed that CuSbS 2 is indeed a very promising absorber material for solar cell application.

This review summarizes recent advances in silver nanoclusters focusing on their controlled synthesis, crystal structures and photoluminescence.

Deformable organic light-emitting diode (OLED) based optoelectronic devices hold promise for various wearable applications including biomedical systems and displays, but current OLED technologies require high voltage and lack the power needed for wearable photodynamic therapy (PDT) applications and wearable displays. This paper presents a parallel-stacked OLED (PAOLED) with high power, more than 100 mW/cm 2 , at low voltage (<8 V). The current dispersion ratio can be tuned by optimizing the structure of the individual OLEDs stacked to create the PAOLED, allowing control of the PAOLED's wavelength shapes, current efficiency, and power. In this study, a fabricated PAOLED operated reliably for 100 h at a high power of 35 mW/cm 2 . Confirming its potential application to PDT, the measured singlet oxygen generation ratio of the PAOLED was found to be 3.8 times higher than the reference OLED. The high-power PAOLED achieved a 24% reduction in melanoma cancer cell viability after a short (0.5 h) irradiation. In addition, a white light PAOLED with color tuning was realized through OLED color combination, and a high brightness of over 30 000 cd/m 2 was realized, below 8.5 V. In conclusion, the PAOLED was demonstrated to be suitable for a variety of low-voltage, high-power wearable optoelectronic applications.

Organic-inorganic halide perovskite solar cells have rapidly come to prominence in the photovoltaic field. In this context, CH NH PbI , as the most widely adopted active layer, has been attracting great attention. Generally, in a CH NH PbI layer, unreacted PbI inevitably coexists with the perovskite crystals, especially following a two-step fabrication process. There appears to be a consensus that an appropriate amount of unreacted PbI is beneficial to the overall photovoltaic performance of a device, the only disadvantageous aspect of excess residual PbI being viewed as its insulating nature. However, the further development of such perovskite-based devices requires a deeper understanding of the role of residual PbI . In this work, PbI -enriched and PbI -controlled perovskite films, as two extreme cases, have been prepared by modulating the crystallinity of a pre-deposited PbI film. The effects of excess residual PbI have been elucidated on the basis of spectroscopic and optoelectronic studies. The initial charge separation, the trap-state density, and the trap-state distribution have all been found to be adversely affected in PbI -enriched devices, to the detriment of photovoltaic performance. This leads to a biphasic recombination process and accelerates the charge carrier recombination dynamics.

Organic-inorganic halide perovskite solar cells are becoming the next big thing in the photovoltaic field owing to their rapidly developing photoelectric conversion performance. Herein, mesoporous structured perovskite devices with various perovskite grain sizes are fabricated by a sequential dropping method, and the charge recombination dynamics is investigated by transient optical-electric measurements. All devices exhibit an overall power conversion efficiency around 15%. More importantly, a biphasic trap-limited charge recombination process is proposed and interpreted by taking into account the specific charge accumulation mechanism in perovskite solar cells. At low Fermi levels, photo-generated electrons predominately populate in the perovskite phase, while at high Fermi levels, most electrons occupy traps in mesoporous TiO2. As a result, the dynamics of charge recombination is, respectively, dominated by the perovskite phase and mesoporous TiO2 in these two cases. The present work would give a new perspective on the charge recombination process in meso-structured perovskite solar cells.

In this paper, a high performance flexible component that serves as a color filter and an electrode simultaneously is suggested. The suggested highly conductive and flexible color filter electrode (CFE) has a multilayer film structure composed of silver (Ag) and tungsten trioxide (WO3). The CFE maintained its color filtering capability even when the films were bent on a polyethylene terephthalate (PET) film. Low sheet resistance of the CFE was obtained using WO3 as a bridge layer that connects two Ag layers electrically. The sheet resistance was less than 2 Ω/sq. and it was negligibly changed after bending the film, confirming the flexibility of the CFE. The CFE can be easily fabricated using a thermal evaporator and is easily patterned by photolithography or a shadow mask. The proposed CFE has enormous potential for applications involving optical devices including large area devices and flexible devices.

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