Tuning Hot Carriers Cooling Rate with Pressure in Hybrid Organic-Inorganic Perovskites*

Mechanical compression provides an effective way to adjust the structures and properties in hybrid organic inorganic perovskites (HOIPs) without changing the chemical composition. An in situ high-pressure femtosecond transient absorption (TA) spectroscopic has been studied here in the prototype MAPbI₃ perovskite thin films, and the pressure response of TA spectrum has been characterized by carrier lifetime, carrier temperature, and hot carrier cooling rate. Both band-gap narrowing and carrier lifetime prolongation has been realized at 1.0 GPa, which may significantly increase the photovoltaic performance. A long carrier building up process due to the extraordinary electron-phonon interaction has been observed at the phase transition critical point. High excitation study show that the applied pressure can significantly reduce the hot carrier cooling rate, while offer higher initial carrier temperature. This study of the mechanisms of compression on carrier dynamics provides insights for the optimal structure design for HOIPs solar cells.