Observation\nof Hot Carrier Localization Affected by\nA Cations in Hybrid Perovskites

Organic–inorganic lead halide perovskites (OLHPs)\nhave demonstrated\nexceptional properties in high-performance photoelectric devices.\nHowever, the impact of A-site cations, specifically formamidinium\nand methylammonium (MA), on the optoelectronic properties of OLHPs,\nparticularly in the context of hot carrier utilization, remains a\ntopic of debate. In this study, we propose a method for characterizing\nhot carrier transportation by measuring the hot carrier mobility and\nmomentum-dependent transient photocurrent influenced by A-site cations\nin OLHPs. Our findings reveal that the direction of photon drag current\nis reversed upon substitution of the MA cation, suggesting the strong\nlocalization of hot carriers by the MA cation dipole. Furthermore,\nthe correlation between the hot carrier photoconductivity and the\nelectronic structure in different A-site cation samples indicates\nthat hot carrier mobility in OLHPs can be reduced by >50% due to\nthe\ninfluence of A-site cations.