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

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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.
Funding Information
  • Office of Naval Research (ONR N00014-14-1-0170)
  • Clean Energy Institute

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