Structural Disorder in Higher-Temperature Phases Increases Charge Carrier Lifetimes in Metal Halide Perovskites

Abstract

Solar cells and optoelectronic devices are exposed to heat that degrades performance. Therefore, elucidating temperature-dependent charge carrier dynamics is essential for device optimization. Charge carrier lifetimes decrease with temperature in conventional semiconductors. The opposite, anomalous trend is observed in some experiments performed with MAPbI3 (MA = CH3NH3 +) and other metal halide perovskites. Using ab initio quantum dynamics simulation, we establish the atomic mechanisms responsible for nonradiative electron–hole recombination in orthorhombic-, tetragonal-, and cubic MAPbI3. We demonstrate that structural disorder arising from the phase transitions is as important as the disorder due to heating in the same phase. The carrier lifetimes grow both with increasing temperature in the same phase and upon transition to the higher-temperature phases. The increased lifetime is rationalized by structural disorder that induces partial charge localization, decreases nonadiabatic coupling, and shortens quantum coherence. Inelastic and elastic electron–vibrational interactions exhibit opposite dependence on temperature and phase. The partial disorder and localization arise from thermal motions of both the inorganic lattice and the organic cations and depend significantly on the phase. The structural deformations induced by thermal fluctuations and phase transitions are on the same order as deformations induced by defects, and hence, thermal disorder plays a very important role. Since charge localization increases carrier lifetimes but inhibits transport, an optimal regime maximizing carrier diffusion can be designed, depending on phase, temperature, material morphology, and device architecture. The atomistic mechanisms responsible for the enhanced carrier lifetimes at elevated temperatures provide guidelines for the design of improved solar energy and optoelectronic materials.

Design, synthesis, and characterization of a new hybrid organic–inorganic perovskite with a high-Tc dielectric transition

“…After the temperature increases, the lattice is distorted, and TEACCl + moves freely. 32,33 It is suggested that the electrons and holes involved in conducting will be excited and increase significantly with TEACCl + disordering and phase changing. Distorted lattice and disordered TEACCl + create better conditions for conducting electrons and cause a step-change of ε ′.…”

Photolysis versus Photothermolysis of N2O on a Semiconductor Surface Revealed by Nonadiabatic Molecular Dynamics

“…This is an order of magnitude longer than the 70 fs time of the dissociation of N 2 O – with the stabilized LUMO, indicating that the photodecomposition of N 2 O occurs prior to the charge recombination. Including the decoherence effect into the simulation of the non-radiative electron–hole recombination will make the recombination longer, − further confirming this conclusion.…”

Control of Charge Carrier Relaxation at the Au/WSe2 Interface by Ti and TiO2 Adhesion Layers: Ab Initio Quantum Dynamics

“…Here, electronic evolution is modeled using real-time TDDFT while classical MD describes the nuclear motions. The electron–nuclear interactions in charge relaxation processes are investigated using fewest-switches surface hopping (FSSH), , one of the most common NAMD methods, as implemented in the PYXAID code under the classical path approximation (CPA). , The methodology has been successfully applied to study excited-state dynamics in various nanoscale systems. − A more detailed description of the time–domain DFT and NAMD methods used can be found in the Supporting Information.…”