No abstract

No abstract

Double perovskite Cs 2 AgInCl 6 is newly reported as a stable and environmentally friendly alternative to lead halide perovskites. However, the fundamental properties of this material remain unexplored. Here, we first produced high-quality Cs 2 AgInCl 6 single crystals (SCs) with a low trap density of 8.6 × 10 8 cm −3 , even lower than the value reported in the best lead halide perovskite SCs. Through systematical optical and electronic characterization, we experimentally verified the existence of the proposed parity-forbidden transition in Cs 2 AgInCl 6 and identified the role of oxygen in controlling its optical properties. Furthermore, sensitive (dectivity of ∼10 12 Jones), fast (3 dB bandwidth of 1035 Hz), and stable UV photodetectors were fabricated based on our Cs 2 AgInCl 6 SCs, showcasing their advantages for optoelectronic applications.

Figure 5. Photovoltaic device structure and performance. SEM images of A) top-view and B) cross-sectional Sb 2 Se 3 fi lm deposited on top of TiO 2 buffer. The thicknesses of v and Sb 2 Se 3 were about 100 nm and 580 nm, respectively. C) Schematic confi guration of TiO 2 /Sb 2 Se 3 heterojunction device. D) J -V curves of Sb 2 Se 3 solar cell performance in the dark and under 100 mW cm −2 simulated AM1.5G irradiation, respectively, and the performance of the device baked at 60 °C for 24 h. The inset shows an the image of our device.

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.

Sb2Se3 is a promising absorber material for photovoltaic cells because of its optimum band gap, strong optical absorption, simple phase and composition, and earth-abundant and nontoxic constituents. However, this material is rarely explored for photovoltaic application. Here we report Sb2Se3 solar cells fabricated from thermal evaporation. The rationale to choose thermal evaporation for Sb2Se3 film deposition was first discussed, followed by detailed characterization of Sb2Se3 film deposited onto FTO with different substrate temperatures. We then studied the optical absorption, photosensitivity, and band position of Sb2Se3 film, and finally a prototype photovoltaic device FTO/Sb2Se3/CdS/ZnO/ZnO:Al/Au was constructed, achieving an encouraging 2.1% solar conversion efficiency.

Physical and optical properties of binary amorphous selenium-antimony thin films

A low defect density in metal halide perovskite single crystals is critical to achieve high performance optoelectronic devices. Here we show the reduction of defect density in perovskite single crystals grown by a ligand-assisted solution process with 3‐(decyldimethylammonio)‐propane‐sulfonate inner salt (DPSI) as an additive. DPSI ligands anchoring with lead ions on perovskite crystal surfaces not only suppress nucleation in solution, but also regulate the addition of proper ions to the growing surface, which greatly enhances the crystal quality. The grown CH3NH3PbI3 crystals show better crystallinity and a 23-fold smaller trap density of 7 × 1010 cm−3 than the optimized control crystals. The enhanced material properties result in significantly suppressed ion migration and superior X-ray detection sensitivity of CH3NH3PbI3 detectors of (2.6 ± 0.4) × 106 µC Gy−1air cm−2 for 60 kVp X-ray and the lowest detectable dose rate reaches (5.0 ± 0.7) nGy s−1, which enables reduced radiation dose to patients in medical X-ray diagnostics.