Electroabsorption Spectroscopy Measurements of the Exciton Binding Energy, Electron–Hole Reduced Effective Mass, and Band Gap in the Perovskite CH3NH3PbI3

Abstract

We use electroabsorption (EA) spectroscopy to measure the exciton binding energy (EB), electron–hole reduced effective mass (μ), and one-electron band gap (Eg) at the fundamental absorption edge of the hybrid organic–inorganic perovskite CH3NH3PbI3 in its tetragonal phase at 300 K. By studying the second-harmonic EA spectra at the fundamental absorption edge we establish that the room-temperature EA response in CH3NH3PbI3 follows the low-field Franz–Keldysh–Aspnes (FKA) effect. Following FKA analysis we find that μ = 0.12 ± 0.03m0, EB = 7.4 meV, and Eg = 1.633 eV. Our results provide direct experimental evidence that at room temperature primary transitions occurring in CH3NH3PbI3 can essentially be described in terms of free carrier generation.