51. Strong high-energy exciton electroluminescence from the light holes of polytypic quantum dots.
- Author
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Wang, Xingzhi, Gao, Yan, Liu, Xiaonan, Xu, Huaiyu, Liu, Ruixiang, Song, Jiaojiao, Li, Bo, Shen, Huaibin, and Fan, Fengjia
- Subjects
QUANTUM dots ,ELECTROLUMINESCENCE ,ELECTRON emission ,EXCITON theory ,LIGHT sources ,PHOTON emission ,ELECTRIC fields - Abstract
High-energy exciton emission could allow single-component multi-colour display or white light-emitting diodes. However, the thermal relaxation of high-energy excitons is much faster than the photon emission of them, making them non-emissive. Here, we report quantum dots with light hole-heavy hole splitting exhibiting strong high-energy exciton electroluminescence from high-lying light holes, opening a gate for high-performance multi-colour light sources. The high-energy electroluminescence can reach 44.5% of the band-edge heavy-hole exciton emission at an electron flux density Φ
e of 0.71 × 1019 s−1 cm−2 − 600 times lower than the photon flux density Φp (4.3 × 1021 s−1 cm−2 ) required for the similar ratio. Our simulation and experimental results suggest that the oscillator strength of heavy holes reduces more than that of light holes under electric fields. We attribute this as the main reason for strong light-hole electroluminescence. We observe this phenomenon in both Cdx Zn1-x Se-ZnS and CdSe-CdS core-shell quantum dots exhibiting large light hole-heavy hole splittings. Previous observations of high-energy exciton electroluminescence rely on filling the ground state with excessive charges, Wang et al. report such observation from quantum dots at low charge concentration by increasing the relative oscillator strength of higher-lying light holes comparing to that of ground-state heavy holes. [ABSTRACT FROM AUTHOR]- Published
- 2024
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