Abstract
Improvement in the optoelectronic performance of halide perovskite semiconductors requires the identification and suppression of nonradiative carrier trapping processes. The iodine interstitial has been established as a deep level defect and implicated as an active recombination center. We analyze the quantum mechanics of carrier trapping. Fast and irreversible electron capture by the neutral iodine interstitial is found. The effective Huang–Rhys factor exceeds 300, indicative of the strong electron–phonon coupling that is possible in soft semiconductors. The accepting phonon mode has a frequency of 53 cm–1 and has an associated electron capture coefficient of 1 × 10–10 cm3 s–1. The inverse participation ratio is used to quantify the localization of phonon modes associated with the transition. We infer that suppression of octahedral rotations is an important factor to enhance defect tolerance.
Highlights
The unusual defect chemistry and physics of lead halide perovskites has attracted significant attention.[1−3] Slow nonradiative electron−hole recombination is unusual for solution processed semiconductors and supports high voltage and efficient light-to-electricity conversion in a solar cell.[4]
We might define ΔQ in the MAPI:Ii system as the root mean squared displacement of the two bonding iodine. For this definition of ΔQ we find that electron trapping at the neutral iodine interstitial proceeds with a small geometrical rearrangement, ΔQ = 0.073 Å, resulting in fast radiative electron capture
The soft nature of halide perovskites results in strong electron−phonon coupling and a large displacement of the surrounding inorganic octahedra following electron capture. This relaxation process leads to a giant Huang− Rhys factor and facilitates fast nonradiative electron capture
Summary
The unusual defect chemistry and physics of lead halide perovskites has attracted significant attention.[1−3] Slow nonradiative electron−hole recombination is unusual for solution processed semiconductors and supports high voltage and efficient light-to-electricity conversion in a solar cell.[4] While significant defect populations are expected based on equilibrium thermodynamics[5] of these soft crystalline materials, and solution processing introduces additional disorder,[6] the native defects do not appear to contribute to nonradiative recombination of electrons and holes. Making use of Fermi’s golden rule, the carrier capture coefficient from an initial state i to a final state f can be described by Received: March 22, 2021 Published: June 9, 2021
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
