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.