Yang Gaoyuan, Shi Shuang, Zhang Xin, Zhou Shuxing, Liu Dezheng, Liang Ying, Chen Zongwei, Liang Guijie
Opt Express. 2021 Mar 15;29(6):9012-9020. doi: 10.1364/OE.414327.
Auger recombination is an ultrafast and unnegligible photophysical process in colloidal semiconductor quantum dots (QDs) due to competition with charge separation or radiative recombination processes, pivotal for their applications ranging from bio-labeling, light-emitting diodes, QD lasing to solar energy conversion. Among diverse QDs, ternary chalcopyrite is recently receiving significant attention for its heavy-metal free property and remarkable optical performance. Given deficient understanding of the Auger process for ternary chalcopyrite QDs, CuInS QDs with various sizes are synthesized as a representative and the bi-exciton lifetime (τ) is derived by virtue of ultrafast time resolved absorption spectrum. The trend of τ varying with size is consistent with the universal scaling of τ versus QD volume (V): τ = γV. The scaling factor γ is 6.6 ± 0.5 ps·nm for CuInS QDs, and the bi-exciton Auger lifetime is 4-5 times slower than typical CdSe QDs with the same volume, suggesting reduced Auger recombination rate in ternary chalcopyrite. This work facilitates clearer understanding of Auger process and provides further insight for rational design of light-harvesting and emitting devices based on ternary chalcopyrite QDs.
俄歇复合是胶体半导体量子点（QDs）中一种超快且不可忽略的光物理过程，这是由于它与电荷分离或辐射复合过程相互竞争，而这些过程对于量子点从生物标记、发光二极管、量子点激光到太阳能转换等应用至关重要。在各种量子点中，三元黄铜矿因其无重金属特性和卓越的光学性能最近受到了广泛关注。鉴于对三元黄铜矿量子点的俄歇过程了解不足，合成了各种尺寸的CuInS量子点作为代表，并借助超快时间分辨吸收光谱得出双激子寿命（τ）。τ随尺寸变化的趋势与τ随量子点体积（V）的普遍标度关系一致：τ = γV。对于CuInS量子点，标度因子γ为6.6±0.5 ps·nm，并且相同体积下双激子俄歇寿命比典型的CdSe量子点慢4 - 5倍，这表明三元黄铜矿中俄歇复合率降低。这项工作有助于更清晰地理解俄歇过程，并为基于三元黄铜矿量子点的光捕获和发光器件的合理设计提供进一步的见解。
