Negative Thermal Quenching in FASnI<sub>3</sub> Perovskite Single Crystals and Thin Films
Simon Kahmann, Olga Nazarenko, Shuyan Shao, Oleh Hordiichuk, Mikaël Képénékian, Jacky Even, Maksym V. Kovalenko, Graeme R. Blake, Maria Antonietta Loi
Abstract
Formamidinium tin triiodide (FASnI3) is a strong contender for sustainable harvesting of solar energy and further optoelectronic applications. So far, only a few studies have considered its fundamental structure–property relationships, given the challenge of ensuring a high material quality. In a concerted effort, we here study high-quality FASnI3 single crystals through a combination of X-ray crystallography, density-functional-theory-based electronic structure calculations, and photoluminescence spectroscopy from room temperature down to 4 K. The luminescence exhibits irregular trends upon cooling with a generally strong intensity increase, but a range of negative thermal quenching, leading to an intensity maximum around 185 K which is absent in low-quality samples. Differences in the photoluminescence peak position and density-functional-theory-calculated band-gap energies highlight the importance of dynamic processes to the observable properties of FASnI3. The presented data offer deeper insight into the temperature-dependent characteristics of this halide perovskite and present opportunities for future exploration of its optoelectronic properties.