Great Influence of Pressure and Isotope Effects on Nonradiative Charge Loss in Hybrid Organic-Inorganic Perovskites

The intrinsic softness of hybrid organic-inorganicperovskites(HOIPs) allows their lattice and optoelectronic performance to betunable to external pressure. Using nonadiabatic (NA) molecular dynamics,we demonstrate that a mild pressure accelerates hot electron relaxationand suppresses nonradiative electron-hole recombination inCH(3)NH(3)PbI(3). Both processes are governedby NA coupling, which is enhanced between the electronic states ofthe quasi-continuous bands while is decreased between the band-edgestates by reducing the electron-hole wave function overlap.Hydrogen/deuterium isotope exchange alleviates the pressure-inducedNA coupling by increasing lattice rigidity and decreasing wave functionoverlap, slowing down both the hot electron relaxation and electron-holerecombination processes. The simulated time scales of sub-3 ps forhot electron relaxation and half nanoseconds for recombination agreewell with the experiments. The study suggests that the isotope exchangecan mitigate the pressure-caused fast losses of hot electrons andfurther prolong the charge carrier lifetime in HOIPs.