Radiative recombination and photoconversion of methylammonium lead iodide perovskite by first principles: properties of an inorganic semiconductor within a hybrid body

The excellent photoconversion properties of lead iodide hybrid perovskites, used as absorber in solar cell devices with power conversion efficiencies exceeding 15%, are explained on the basis of ab initio calculated radiative recombination rates and minority carrier lifetimes. Brad ∼ (0.5-1.5) × 10-9 s-1 cm3 and minority lifetime ∼103 ns were obtained for a doping concentration of n ∼ 1015 cm-3 at room temperature. These values, comparable to those of typical optoelectronic semiconductors (e.g., GaAs), reflect the very nature of the perovskite: fully solution-processable owing to its hybrid nature, and yet a truly inorganic semiconductor for with regard to photoconversion properties. Recombination rates are also used to quantitatively describe the maximum limit of power conversion efficiency potentially achievable by these systems, for example, 21% for a 200 nm thick perovskite film and 23% for a 300 nm thickness.