Charge carrier migration and hole extraction from MAPbI3

Abstract

Linear as well as time resolved absorption measurements were performed on 40 nm and 170 nm thick MAPbL films with PEDOT:PSS hole extraction layer, spin-coated on quartz substrate. From linear absorption measurements exciton binding energy of 18 - 19 meV and band gap of 1.60 - 1.62 eV was deduced. Transient absorption spectra after the excitation at 1.77 eV showed a strong difference in carrier recombination dynamics for the two MAPbI3 films of different thicknesses. From the analysis on the decay dynamics, hole population lifetime of 0.3 ns and 3.5 ns for 40 nm and 170 nm films, respectively, are determined. A numerical 1D diffusion model was used to model the carrier relaxation dynamics yielding hole diffusion constants of 0.025 - 0.030 cm2s-1, which results in a hole mobility of 1 cm2(Vs)-1 in these MAPbI3 films.