(604f) Improved Charge Collection in Highly Efficient CsPbBrI2 Solar Cells with Light-Induced Dealloying

The meteoritic rise of solar cell efficiencies based on low-cost solution processed metal halide perovskites (MHPs) is raising an exciting possibility of accelerating wide-spread usage of solar power. To realize this potential, the poor stability of MHP solar cells has been identified as a major challenge to be overcome. The majority of MHP solar cells to date have been based on hybrid organic-inorganic MHPs that undergo thermal degradation at temperatures which can be commonly reached at geographic locations. Moreover, interaction between the organic moieties and water has been identified as a predominant degradation pathway.

Recently, all-inorganic, Cs⁺ ion-based lead halide perovskites have been proposed as a means to overcome the instability issues of organic cations in hybrid MHPs. In this talk, I will present our results that show the importance of halide dealloying in CsPbBrI₂ perovskite solar cells in solar cell performance. This dealloying occurs under steady illumination and is a reversible process, suggesting transitions between equilibrium states under dark and illuminated environments. Through decoupling charge collection in the electron- and hole-transporting layers, our photoluminescence, X-ray diffraction, and solar cell device characterization results suggest that the light-induced halide dealloying improves hole collection in solar cells, resulting in increased efficiency (9.2% ± 0.64 on average with a champion efficiency of 10.3%). Our results provide deeper insights on the impact of dealloying on perovskite solar cell performance and highlight the growing potential of all-inorganic perovskite solar cells.