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.