The Physics of Ultra-Long Cooling Times in Metal Halide Perovskites

Abstract Ultra-long cooling times are the most crucial ingredient for the successful development of a hot-carrier solar cell. Recent experimental reports for metal halide perovskites show the possibility of reaching these relevant values using Sn-based perovskite compositions, due to their low effective mass. In this work, the governing underlying physics is uncovered by investigating the interplay between band filling and the hot phonon bottleneck effect. By using ensemble Monte Carlo simulations and through comparison with time-resolved photoluminescence measurements, it is demonstrated that solely the combination of these two phenomena is sufficient to reproduce ultra-long carrier cooling times. The dependency of band filling on material parameters is analyzed, and it is crucially shown that carriers affected by band filling remain hot in terms of their Fermi–Dirac temperature for the remainder of their energy relaxation period. Our results are important in the discussion regarding the suitability of metal halide perovskites for future HCSC applications, and function as a road-map towards the successful construction of a perovskite-based HCSC.