Franz-Keldysh and Stark Effects in Two-Dimensional Metal Halide Perovskites

Abstract

The established theory of a two-dimensional (2D) Wannier exciton in a uniform electric field is used to analyze the electroabsorption response of an archetypal 2D metal halide perovskite (MHP), phenethylammonium lead iodide. The high level of agreement between the electroabsorption simulation and measurement allows for a deepened understanding of the redshift of exciton energy, according to the quadratic Stark effect, and the continuum wave function leaking, according to the Franz-Keldysh effect. We find the field dependency of each of these effects to be rich with information, yielding measurements of the exciton Bohr radius, transition dipole moment, polarizability, and reduced effective mass of the exciton. Most importantly, the band-gap energy and exciton binding energy are unambiguously determined with 1σ variance of 4 meV. The high precision of these new measurement methods opens the opportunity for determining the influence of chemical and environmental factors on the optoelectronic properties of MHPs, which would enable the fabrication of highly efficient and reproducible light-harvesting and light-emitting optoelectronic devices.8 MoreReceived 21 September 2021Revised 22 December 2021Accepted 2 February 2022DOI:https://doi.org/10.1103/PRXEnergy.1.013001Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasStark effectPhysical SystemsPerovskitesQuantum wellsTechniquesOptical absorption spectroscopyCondensed Matter, Materials & Applied Physics