Tailoring Carrier Dynamics by Band Alignment Engineering in Quasi-2D Perovskite LED.
basic_science · Level V
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- Record sourced from PubMed, PMID 41122953.
- Also identified by DOI 10.1021/acs.nanolett.5c04309.
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Abstract
Band alignment of semiconductors is a crucial factor in the construction of efficient optoelectronic devices. However, no studies have reported on the impact of the phase distribution in quasi-2D lead halide perovskites on band alignment and carrier dynamics. Herein, an alteration in band alignment is achieved by intentionally optimizing phase distribution in a (PEA)<sub>2</sub>CsPb<sub>2</sub>I<sub>7</sub> quasi-2D film via the addition of a crown ether. It is experimentally evidenced that the band alignment can be engineered from type II to type I for the crown-induced narrowing of the phase distribution, which results in enhanced electron-phonon coupling and increased exciton binding energy. As a consequence, accelerated hot carrier cooling, suppressed Auger recombination, and enhanced exciton recombination are observed in the crown-treated sample. Finally, benefiting from band alignment engineering, the peak external quantum efficiency of the constructed light-emitting diode is improved from 7.4% to 20.1%.