Exploring the photo-induced charge transfer behavior of Cs₃Bi₂I₉ and BiI₃ using in-situ surface photovoltage spectroscopy

This letter compared the photo-induced charge carrier properties of Cs₃Bi₂I₉ and BiI₃ deposited on conductive glass using surface photovoltage spectroscopy. The study showed that the higher photocurrent in BiI₃ cannot be solely attributed to its extended absorbance range. The charge transfer capability of the photoactive layer was found to be a critical factor in determining photocurrent. The study also revealed better transfer of photo-induced electron-hole pairs and higher surface electron concentration in BiI₃. Additionally, light-chopping-frequency-dependent surface photovoltage measurements showed that photogenerated charge carriers can be separated more effectively and in a shorter illumination period in BiI₃ than in Cs₃Bi₂I₉.