混合卤化物钙钛矿相分离的热力学稳定化
Thermodynamic stabilization of mixed-halide perovskites against phase segregation
摘要：
在卤化物钙钛矿半导体中混合碘化物和溴化物是调节其带隙的有效策略，因此混合卤化物钙钛矿在颜色可调LED和串联太阳能电池中具有很大的前景。然而，混合卤化物钙钛矿的带隙在（太阳）光下是不稳定的，因为卤化物分离成不同带隙的域。使用压力相关的超快瞬态吸收光谱，我们表明，高的外部压力增加的范围内的化学稳定的卤化物混合比。化学压力，通过插入一个较小的阳离子，具有相同的效果，这意味着任何碘溴比可以通过调整晶体体积和压缩性来稳定。我们解释这种稳定的亥姆霍兹自由能的改变，通过在很大程度上被忽视的PdeltaV长期。
英文摘要：
Mixing iodide and bromide in halide perovskite semiconductors is an effective strategy to tune their bandgap, therefore mixed-halide perovskites hold great promise for color-tunable LEDs and tandem solar cells. However, the bandgap of mixed-halide perovskites is unstable under (sun-)light, since the halides segregate into domains of different bandgaps. Using pressure-dependent ultrafast transient absorption spectroscopy, we show that high external pressure increases the range of thermodynamically stable halide mixing ratios. Chemical pressure, by inserting a smaller cation, has the same effect, which means that any iodide-to-bromide ratio can be thermodynamically stabilized by tuning the crystal volume and compressibility. We interpret this stabilization by an alteration of the Helmholtz free energy via the largely overlooked PdeltaV term.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
