The high performance of recently emerged lead halide perovskite based photovoltaic devices has been attributed to remarkable carrier properties in this kind of material: long carrier diffusion length, long carrier lifetime, and low electron-hole recombination rate. However, the charge separation mechanism underlying such carrier properties is still debated in this research field. In this work, using first-principles molecular dynamics simulations, we have demonstrated that the charge separation is induced by the structural fluctuation of the inorganic lattice, assuming that the charge carriers occupy the band edge. It is shown that the charge separation is attributed to the electrostatic potential fluctuation coupled to the inorganic lattice dynamics, on the basis of both simple tight-binding-model-based analyses and first-principles calculations. These results suggest that the organic cations, which are often used as components of lead halide perovskites, are unlikely to be essential for the above-mentioned carrier properties. Hence, it is expected that all-inorganic lead halide perovskite based photovoltaics might be able to rival organic-inorganic lead halide perovskite based ones in performance.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films