Improved Efficiency and Stability in Inverted-Structure Solar Cells with Lead-Free All-Inorganic Halide Perovskite CsSnZnBr.

We report the fabrication of an inverted structure solar cell with all-inorganic lead-free perovskite CsSnZnBr alloy thin films grown by physical vapor codeposition of CsBr, SnBr, and ZnBr. It was found that the deposited CsSnZnBr perovskite alloy thin films exhibited improved morphological characteristics (larger grain sizes, lower pinhole density, and improved flatness) compared to the CsSnBr thin film. The incorporation of 4% Zn (CsSnZnBr, abbreviated as 4Zn) resulted in a bandgap narrowing of ∼20 meV compared to CsSnBr with the upshift of the valence band maximum and conduction band minimum of ∼0.

Exciton dynamics in CsPbBr3 single crystal: LT splitting energy, exciton-polariton dispersion, and biexciton binding energy.

Metal halide perovskite materials (MHPs) are promising for several applications due to their exceptional properties. Understanding excitonic properties is essential for exploiting these materials. For this purpose, we focus on CsPbBr3 single crystals, which have higher crystal quality, are more stable, and have no Rashba effect at low temperatures compared to other 3D MHPs.

Bulk Photovoltaic Effect Along the Nonpolar Axis in Organic-Inorganic Hybrid Perovskites.

The origin of the bulk photovoltaic effect (BPVE) was considered as a built-in electric field formed by the macroscopic polarization of materials. Alternatively, the "shift current mechanism" has been gradually accepted as the more appropriate description of the BPVE. This mechanism implies that the photocurrent generated by the BPVE is a topological current featuring an ultrafast response and dissipation-less nature, which is very attractive for photodetector applications.

Highly-efficient terahertz emission from hydrogen-bonded single molecular crystal 4-nitro-2,5-bis(phenylethynyl)aniline.

We report terahertz electromagnetic wave emission by optical rectification from hydrogen-bonded single molecular crystal 4-nitro-2,5-bis(phenylethynyl)aniline designed to be polar via the hydrogen bonding between nitroaniline cores. The terahertz emission efficiency is comparable to the representative inorganic terahertz emitter ZnTe. We show terahertz emission characteristics, optical spectrum, and theoretical molecular orbital calculations.

Defect tolerant zero-bias topological photocurrent in a ferroelectric semiconductor.

Lattice defect is a major cause of energy dissipation in conventional electric current due to the drift and diffusion motions of electrons. Different nature of current emerges when noncentrosymmetric materials are excited by light. This current, called the shift current, originates from the change in the Berry connection of electrons' wave functions during the interband optical transition.