Dependance of CsPbI3 Perovskite Phase Transformation on Humidity

Riley Nelson1, Rory M Campagna1, Samuel Smith1, Zachery R Wylie1,2, Jeffrey A Christians1 1Hope College, Holland, MI, United States /2University of Washington, Seattle, WA, United States

Lead- and tin-based halide perovskites offer a combination of optoelectronic properties that make them widely studied for next-generation photovoltaics, light emitting diodes, detectors, and more. The potential combination of low-cost manufacturing and high performance has initiated this interest; however, the poor thermal stability of organic-inorganic halide perovskites has spurred the continued investigation of all-inorganic halide perovskites. The switch to all-inorganic compositions opens up the potential for phase transformations from the perovskite phase and into a nonperovskite hexagonal phase. In this work, we aim to further describe the dynamics of this perovskite to nonperovskite phase transition across a range of temperatures and humidities. We demonstrate an exponential dependance on the partial pressure of atmospheric water and a nearly linear decrease in rate with increasing temperature. Ongoing work will seek to more fully describe the kinetics of the perovskite to nonperovskite phase transformation with the goal of improving the predictive value of accelerated test protocols and enabling more robust all-inorganic halide perovskite materials.