Trap passivation and suppressed electrochemical dynamics in perovskite solar cells with C60 interlayers

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Publication date
DOI http://dx.doi.org/10.1016/j.electacta.2022.141215
Reference Tulus, L.A. Muscarella, Y. Galagan, S.C. Boehme and E. von Hauff, Trap passivation and suppressed electrochemical dynamics in perovskite solar cells with C60 interlayers, Electrochim. Acta 433, 141215: 1-10 (2022)
Group Hybrid Solar Cells

In this study, we quantify the impact of C60-passivation layers in Cs0.15FA0.85PbI2.75Br0.25 double-cation perovskite solar cells. We apply a combination of impedance spectroscopy, photoluminescence (PL) spectroscopy, and X-ray diffraction (XRD) to identify the origin for the increase in power conversion efficiencies and operational stability for solar cells fabricated with C60/ZnO electron transport layer (ETL) versus reference cells with a ZnO ETL. XRD reveals an increase in PbI2 while PL spectroscopy reveals an increase in Br-rich regions in the perovskite bulk in devices containing C60 interlayers. We apply impedance spectroscopy to quantify the electrochemical dynamics in both solar cell architectures. Solar cells with C60/ZnO ETL demonstrate less pronounced and slower electrochemical dynamics in the impedance spectra than solar cells with ZnO ETL. We conclude that C60 leads to the formation of PbI2-rich and Br-rich domains in the perovskite absorber layer, resulting in reduced recombination losses and improved operational stability.