Band-Gap Tuning of Organic-Inorganic Hybrid Palladium Perovskite Materials for a Near-Infrared Optoelectronics Response.

Organic-inorganic hybrid material is a recent hot topic in the scientific community. The best band gap for the entire solar absorption spectrum is about 1.1 eV. However, the lead perovskite band gap is about 1.5 eV. Therefore, developing organic-inorganic hybrid material toward the broader light harvesting of the solar spectrum is extremely urgent. In this study, we prepare three kinds of organic-inorganic hybrid palladium perovskite materials, including (CH3NH3)2PdCl4, (CH3NH3)2PdCl4-x Br x , and CH3NH3PdI3, for an optoelectronic response. The absorption cut offs of (CH3NH3)2PdCl4, (CH3NH3)2PdCl4-x Br x , and CH3NH3PdI3 are approximately 600, 700, and 1000 nm, respectively. The band gaps of (CH3NH3)2PdCl4, (CH3NH3)2PdCl4-x Br x , and CH3NH3PdI3 are determined to be approximately 2.15, 1.87, and 1.25 eV, respectively. To the best of our knowledge, this is the first study that discusses adsorption properties and photoelectric behavior of organic-inorganic hybrid palladium perovskite materials. Interestingly, the photoelectric response of the devices based on CH3NH3PdI3 reaches 950 nm. The results will attract attention in the fields of optical recorders, optical memory, security, light capture, and light treatment.

Synthesis, Crystal Structure, UV-Vis Adsorption Properties, Photoelectric Behavior, and DFT Computational Study of All-Inorganic and Lead-Free Copper Halide Salt K2Cu2Cl6.

In this study, all-inorganic copper halide salt K2Cu2Cl6 single-crystal and thin films were prepared. The single-crystal diffraction data belonged to the monoclinic K2Cu2Cl6 (space group = P 2(1)/C, unit cell parameters of a = 4.0340 Å, b = 13.7987 Å, c = 8.7445 Å, α = 90.000, ß = 97.123, and γ = 90.000). As far as we know, this is the first study of the copper halide salt K2Cu2Cl6 for optoelectronic applications. The band gap of K2Cu2Cl6 is calculated to be approximately 1.85 eV. A low-cost photodetector based on the K2Cu2Cl6 thin film was efficient under different monochromatic light from 330 to 390 nm with different chopping frequencies (1.33-30 Hz). Density functional theory (DFT) computational results indicate that the valence bands (VBs) and conduction bands (CBs) are shifted up in energy using the orbital-dependent correction to the DFT energy. Partial density of states reveals that the VBs and narrow CBs are derived from the hybrid orbitals of Cu2+ 3d and Cl- p, respectively.

Earth-abundant and environment friendly organic-inorganic hybrid tetrachloroferrate salt CH3NH3FeCl4: structure, adsorption properties and photoelectric behavior.

Organic-inorganic hybrid-based lead perovskites show inherent and unavoidable problems such as structural instability and toxicity. Therefore, developing low-cost and environment-friendly organic-inorganic hybrid materials is extremely urgent. In this study, we prepared earth-abundant and environment-friendly organic-inorganic hybrid tetrachloroferrate salt CH3NH3FeCl4 (MAFeCl4) for optoelectronic applications. The single crystal diffraction data are assigned to the orthorhombic MAFeCl4 (Pnma space group), with parameters a = 11.453 (5) Å, b = 7.332 (3) Å, c = 10.107 (5) Å, α = 90.000, ß = 90.000, and γ = 90.000. The band gap of MAFeCl4 is approximately 2.15 eV. Moreover, three-emission luminescence (398, 432 and 664 nm) was observed. To the best of our knowledge, this is the first study involving the investigation of the structure, adsorption properties and photoelectric behavior of MAFeCl4. A low cost photodetector based on the MAFeCl4 thin film is efficient under different monochromatic light from 330 nm to 410 nm with different chopping frequencies (1.33 Hz to 40 Hz). The photoelectric conversion efficiency based on FTO/TiO2/MAFeCl4/carbon electrode device reaches 0.054% (V oc = 319 mV, J sc = 0.375 mA cm-2, and fill factor = 0.45) under AM1.5, 100 mW cm-2 simulated illumination. Our findings will attract attention from the magnetic, piezoelectric and photoelectronic research fields.

Low defects, large area and high stability of all-inorganic lead halide perovskite CsPbBr3 thin films with micron-grains via heat-spraying process for self-driven photodetector.

All-inorganic lead halide perovskite CsPbBr3 has important applications in photoelectronic devices such as photodetectors, LEDs and photovoltaic devices. However, preparing high-quality CsPbBr3 thin films has proven to be challenging. In this study, we prepared all-inorganic lead halide perovskite CsPbBr3 thin films with micron-grains (MG-CsPbBr3-TF) via a heat-spraying process (HSP) using a CsPbBr3-saturated solution (CsPbBr3-SS), and the films exhibited large area, low defects and high stability. The grain size of MG-CsPbBr3-TF was about 1-5 microns. The micron-sized grains in MG-CsPbBr3-TF enabled the absorption cutoff edge to be extended from 537 to 545 nm. In addition, the presence of fewer boundaries in MG-CsPbBr3-TF reduced the defects in MG-CsPbBr3-TF (the blue shift of luminescence). The response wavelengths of a low-cost and self-driven (zero-biased) photodetector based on MG-CsPbBr3-TF were from 330 to 600 nm. CsPbBr3 thin films having a large area (10 cm × 10 cm) and micron-sized grains were also prepared by HSP and exhibited excellent stability (1944 h) in air (T = 298 K, 40% humidity). To the best of our knowledge, this is the first study of high-quality CsPbBr3 thin films prepared by HSP. The results are of great interest for both fundamental research and practical applications of CsPbBr3 in photodetectors, LEDs and photovoltaic devices.