AP Seminar - Electron Dynamics Governed by Lattice Energy Reservoirs in Metal Halide Perovskites

Metal halide perovskites (MHPs) have emerged as promising materials for high-performance photovoltaics and optoelectronics, which is basically ascribed to the superior optoelectronic properties. However, a suite of anomalous electron dynamics observed in metal halide perovskites, including dynamic defect tolerance, persistent structural polarization, and unconventional memory effects, challenges the foundations of established semiconductor theory. We propose a new theory — the Lattice Energy Reservoir (LER)¹ —as the fundamental origin of the superior optoelectronic properties observed in halide perovskites. It is LERs, non-uniformly localized nanodomains, that introduce unique energy recycle of hot phonon injection to LER, energy storage of lattice deformation as phonon cavity and then subgap carrier upconversion driven by LER; which governs electron dynamics of perovskites. In other words, LERs comprehensively redefine electron dynamics from femtoseconds to hours, such as slowed hot-carrier cooling, variable and extended carrier lifetimes, dynamic defect tolerance, persistent structural polarization, memory effects, and illumination-induced transparency.
LERs theory introduces fully different insight into MHP’s electron dynamics and also redefine electron dynamics in soft lattice semiconductors. A revolutionary photovoltaic concept, Lattice Battery Solar Cell (LBSC)², is proposed based on the Lattice Energy Reservoir (LER) theory, which inherently eliminates two major energy losses of conventional solar cells with theoretically conversion efficiency exceeding 70%. At the same time, a new strategy for resolving instability of MHPs by anti-Stokes cooling has resulted in very promising results for intrinsically overcome the instability of MHPs.