Chalcogenide Perovskite Thin Films with Controlled Phases for Optoelectronics

Abstract

Chalcogenide perovskites have emerged as promising semiconductor materials due to their appealing properties, including tunable bandgaps, high absorption coefficients, reasonable carrier lifetimes and mobilities, excellent chemical stability, and environmentally benign nature. However, beyond the well‐studied BaZrS3, reports on chalcogenide perovskite thin films with diverse compositions are scarce. In this study, the realization of four different types of chalcogenide perovskite thin films with controlled phases, through CS2 annealing of amorphous chalcogenide precursor films deposited by pulsed laser deposition (PLD), is reported. This achievement is guided by a thorough theoretical investigation of the phase stability of chalcogenide perovskites. Upon crystallization in the distorted perovskite phase, all materials exhibit photoluminescence (PL) with peak positions in the visible range, consistent with their expected bandgap values. However, the full‐width‐at‐half‐maximum (FWHM) of the PL spectra varies significantly across these materials, ranging from 99 meV for SrHfS3 to 231 meV for BaHfS3. The difference is attributed to the difference in kinetic barriers between local structural motifs for the Sr and Ba compounds. The findings underscore the promise of chalcogenide perovskite thin films as an alternative to traditional halide perovskites for optoelectronic applications, while highlighting the challenges in optimizing their synthesis and performance.

Thermal Stability of Chalcogenide Perovskites

“…In the case of SrZrS 3 and SrHfS 3 , the thermodynamically most stable phase at RT is the nonperovskite NL phase . However, depending on the experimental conditions, the compositions can also be prepared in the form of a phase metastable DP phase . While the conversion of metastable DP phase to stable NL phase is reversible, the conversion temperatures are quite high; e.g., 750 °C in the case of SrZrS 3.…”

Wide-Gap p-Type Layered Oxychalcogenides AE2CuInO3Ch (AE: Alkaline Earth; Ch: Chalcogen): Unusually Low Residual Carrier Concentration and Green-to-Red Emission

“…Such a circumstance implies that the “green gap” is the fundamental and intrinsic problem that might be difficult to solve only by the III-V group materials. Thus, exploration of new green light-emitting semiconductor materials with band gaps ( E g ) of 2.2–2.5 eV (approximately 490–560 nm) has been actively performed, boosting recent proposals of new inorganic candidate materials. − …”