Monitoring hot exciton dissociation in hybrid lead halide perovskite films with sub-10 fs pulses

Sub-10 fs pump-probe experiments on methylammonium lead halide (MAPbI3 ) perovskite films show hot exciton dissociation in 20 fs after photo-excitation with ~0.7 eV excess energy compared to its optical band gap (BG). Coherent wave packets were also detected in the form of spectral modulation, revealing electron-phonon coupling in these materials. The estimated electron-phonon coupling strengths from the frequency and amplitude of the detected spectral modulation are in the weak regime, suggesting formation of large polaron.