Effect of Zinc-doping on the Reduction of the Hot-carrier Cooling Rate in Halide Perovskites.

Fast hot-carrier cooling process in the solar-absorbers fundamentally limits the photon-energy conversion efficiencies. It is highly desirable to develop the solar absorber with long-lived hot-carriers at sun-illumination level, which can be used to develop the hot-carrier solar cells with enhanced efficiency. Herein, we reveal that zinc-doped (0.34%) halide perovskites have the slower hot-carrier cooling compared with the pristine sample through the transient absorption spectroscopy measurements and theoretical calculations. The hot-carrier energy loss rate at the low photoexcitation level of 10 17 cm -3 is found to be ~3 times smaller than that of un-doped perovskites for 500-K hot carriers, and up to ten times when the hot-carrier temperature approaching the lattice temperature. The incorporation of zinc-dopant into perovskites can reduce the nonadiabatic couplings between conduction bands, which retards the photogenerated hot-carriers relaxation process. Our findings present a practical strategy to slow down the hot-carrier cooling in perovskites at low carrier densities, which are valuable for the further development of practical perovskite hot-carrier photovoltaics .