Wang Xingzhi, Gao Yan, Liu Xiaonan, Xu Huaiyu, Liu Ruixiang, Song Jiaojiao, Li Bo, Shen Huaibin, Fan Fengjia
CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei, China.
Hefei National Laboratory, University of Science and Technology of China, Hefei, China.
Nat Commun. 2024 Jul 27;15(1):6334. doi: 10.1038/s41467-024-50432-8.
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 of 0.71 × 10 s cm - 600 times lower than the photon flux density Φ (4.3 × 10 s cm) 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 CdZnSe-ZnS and CdSe-CdS core-shell quantum dots exhibiting large light hole-heavy hole splittings.
高能激子发射可实现单组分多色显示或白色发光二极管。然而，高能激子的热弛豫比它们的光子发射快得多，导致它们不发光。在此，我们报道了具有轻空穴-重空穴分裂的量子点，其从高能轻空穴表现出强烈的高能激子电致发光，为高性能多色光源打开了一扇大门。在电子通量密度Φ为0.71×10 s cm时，高能电致发光可达到带边重空穴激子发射的44.5%，这一比类似比例所需的光子通量密度Φ（4.3×10 s cm）低600倍。我们的模拟和实验结果表明，在电场作用下，重空穴的振子强度比重空穴降低得更多。我们将此归因于强光空穴电致发光的主要原因。我们在表现出大的轻空穴-重空穴分裂的CdZnSe-ZnS和CdSe-CdS核壳量子点中都观察到了这一现象。
