Department of Chemical and Biomolecular Engineering, Tandon School of Engineering, New York University, Brooklyn, New York 11201, United States.
J Phys Chem Lett. 2023 Mar 30;14(12):3000-3006. doi: 10.1021/acs.jpclett.3c00303. Epub 2023 Mar 21.
CsAgInBr is among the lead-free halide perovskites of interest, predicted by first-principles calculations to be stable with a direct band gap, but there has been only one report of its synthesis. Herein we report the formation of CsAgInBr thin films through thermal evaporation of CsBr, AgBr, and InBr and subsequent annealing between 130 °C and 250 °C. CsAgInBr appears stable in this temperature range. However, CsAgInBr thin films are thermodynamically unstable at room temperature, remaining cubic only long enough to be characterized but not long enough to be useful for practical devices. CsAgInBr decomposed into CsAgBr, CsInBr, AgBr, and InBr upon cooling from 130 °C to 250 °C to room temperature. This conclusion did not depend on illumination, film thickness, annealing environment, or details of the film formation, pointing to an intrinsic thermodynamic instability of the material. Optical absorption measurements may be interpreted as CsAgInBr having a direct band gap of 1.57 ± 0.1 eV.
CsAgInBr 是一种无铅卤化物钙钛矿，通过第一性原理计算预测其具有直接带隙，是稳定的，但目前仅报道过一次其合成方法。本文通过热蒸发 CsBr、AgBr 和 InBr 并在 130°C 至 250°C 之间退火，报告了 CsAgInBr 薄膜的形成。在这个温度范围内，CsAgInBr 是稳定的。然而，CsAgInBr 薄膜在室温下热力学上不稳定，仅在足够的时间内保持立方相以进行表征，但不足以用于实际器件。CsAgInBr 在从 130°C 冷却到 250°C 再到室温的过程中分解为 CsAgBr、CsInBr、AgBr 和 InBr。这个结论不依赖于光照、薄膜厚度、退火环境或薄膜形成的细节，表明该材料存在内在的热力学不稳定性。光学吸收测量可以解释为 CsAgInBr 具有 1.57±0.1eV 的直接带隙。
