High-temperature phase CsPbI₃ has garnered increased attention due to its suitable band gap for photovoltaics, but its structural instability under ambient conditions limits its long-term application. While there have been studies on its structural stability under heat and moisture, insight on the influence of light absorption is limited. We demonstrate that, under ambient moisture, illumination by an above-band gap laser transforms high-temperature CsPbI₃ into its low-temperature phase at rates that are orders of magnitude larger than that of the moisture-induced phase transformation alone, likely due to additional surface vacancy creation and/or migration. Without moisture, laser illumination does not trigger the phase transformation, but introduces defects that lower the material’s photoluminescence intensity and accelerate the high-temperature to low-temperature phase transformation when the sample is exposed to moisture. These results expand our understanding of the influence of light exposure on CsPbI₃ and highlight the interdependencies at play when subjecting CsPbI₃ to combined environmental stimuli.

高温相CsPbI ₃因其适合光伏的带隙而受到越来越多的关注，但其在环境条件下的结构不稳定性限制了其长期应用。虽然已经对其在热和湿气下的结构稳定性进行了研究，但对光吸收影响的了解是有限的。我们证明，在环境湿度下，带隙以上激光的照射会转变高温 CsPbI ₃以比单独的水分诱导相变大几个数量级的速率进入其低温阶段，这可能是由于额外的表面空位产生和/或迁移。在没有水分的情况下，激光照射不会触发相变，但会引入缺陷，降低材料的光致发光强度，并在样品暴露于水分时加速高温到低温的相变。这些结果扩大了我们对光照对 CsPbI ₃影响的理解，并突出了 CsPbI ₃受到组合环境刺激时的相互依赖性。