A Review of Properties, Synthesis and Applications on Lanthanum Copper Oxychalcogenides

The study of layered materials has been a significant and fascinating area due to their unique physical and chemical properties. Among various layered materials, lanthanum copper oxychalcogenides (LaCuOX (X=S, Se, Te)) have drawn a lot of attention of researchers. The study of LaCuOX was initially focused on the optoelectronic performance due to its excellent optical and electronic properties. Recently, it was found that the layered LaCuOX material also exhibits good thermoelectric properties, providing an opportunity to achieve high energy conversion efficiency through the thermoelectric effects. In this report, an overview of recent advances in LaCuOX research is provided, including crystal and electronic structure, synthetic methods, physical properties, practical applications as well as some strategies to optimize their transport properties. Theoretical and experimental results on LaCuOX crystals or thin films are both discussed in this report. Finally, the challenges and outlook for LaCuOX are evaluated based on current progress.

Crystallographic and optical properties of wide bandgap photovoltaic semiconductor system, Cu(Al,In)Se2

We characterized the optical and electronic properties of chalcopyrite-type Cu(Al,In)Se2, which is a candidate for wide-bandgap solar cell materials. The bandgap energy was determined from diffuse reflectance spectra. The band gap energy increased from 1.00 eV for CuInSe2 to 2.61 eV for CuAlSe2 with an increase in the Al content. The ionization energy corresponding to the energy levels of the valence band maximum (VBM) was determined using photoemission yield spectroscopy (PYS). The VBM level of the Cu(Al,In)Se2 system stayed relatively constant, but the conduction band minimum (CBM) level increased with increasing Al content. To analyze the local structures of Cu and In atoms in Cu(Al,In)Se2, Cu and In K-edge X-ray absorption fine structure (XAFS) spectra were measured at SPring-8. We discuss the crystallographic characteristics of Cu(Al,In)Se2 based on the results of the XAFS analyses and a comparison of the phase diagrams of the Cu2Se-Al2Se3, Cu2Se-In2Se3, and Cu2Se-Ga2Se3 systems.

Improved Optical and Electronic Properties of Single-Layer MoS2 by Co Doping for Promising Intermediate - Band Materials

Owing to its unique optical and electronic characteristics, two-dimensional MoS2 has been widely explored in the past few years. Using first-principle calculations, we shed light on that the substitutional doping of Co can induce the half-filled intermediate states in the band gap of monolayer MoS2. The calculated absorption spectrum presents an enhancement of the low-energy photons (0.8 eV–1.5 eV), which is desired for intermediate-band solar cells. When the doping concentration increases, the reflectivity of the infrared and visible light (0.8 eV-4.0 eV) reduces, resulting in an improved photovoltaic efficiency of the material. Our results shed light on the application of heavily Co-doped MoS2 as intermediate band solar cell material.

Two-step nonlinear optical switch in a hydrogen-bonded perovskite-type crystal

Switchable nonlinear optical (NLO) materials have aroused broad interest on account of their captivating optical and electronic properties. We demonstrate a novel perovskite-type crystal with exceptional hydrogen bond interactions that...

The Impact of Twisting on the Intersystem Crossing in Acenes: An Experimental and Computational Study

Due to their unique excited state dynamics, acenes play a dominant role in optoelectronic and light-harvesting applications. Their optical and electronic properties are typically tailored by side-group engineering, which often...