Abstract
2D perovskite materials have recently reattracted intense research interest for applications in photovoltaics and optoelectronics. As a consequence of the dielectric and quantum confinement effect, they show strongly bound and stable excitons at room temperature. Here, the band-edge exciton fine structure and in particular its exciton and biexciton dynamics in high quality crystals of (PEA)2PbI4 are investigated. A comparison of bulk and surface exciton lifetimes yields a room temperature surface recombination velocity of 2 × 103 cm s−1 and an intrinsic lifetime of 185 ns. Biexciton emission is evidenced at room temperature, with a binding energy of ≈45 meV and a lifetime of 80 ps. At low temperature, exciton state splitting is observed, which is caused by the electron–hole exchange interaction. Transient photoluminescence resolves the low-lying dark exciton state, with a bright/dark splitting energy estimated to be 10 meV. This work contributes to the understanding of the complex scenario of the elementary photoexcitations in 2D perovskites.
Original language | English |
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Article number | 1907979 |
Number of pages | 9 |
Journal | Advanced Functional Materials |
Volume | 30 |
Issue number | 6 |
Early online date | 9-Dec-2019 |
DOIs | |
Publication status | Published - 5-Feb-2020 |
Keywords
- biexciton
- dark exciton
- exciton state splitting
- layered perovskite
- ultrafast dynamics
- CHARGED EXCITONS
- BINDING-ENERGY
- BIEXCITONS
- NANOCRYSTALS
- PHOTOLUMINESCENCE
- EMISSION
- STATES