Yan Dongdong, Shi Tongchao, Zang Zhigang, Zhou Tingwei, Liu Zhengzheng, Zhang Zeyu, Du Juan, Leng Yuxin, Tang Xiaosheng
Key Laboratory of Optoelectronic Technology & Systems (Ministry of Education), Chongqing University, Chongqing, 400044, China.
State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, 201800, China.
Small. 2019 Jun;15(23):e1901173. doi: 10.1002/smll.201901173. Epub 2019 Apr 29.
The poor stability and aggregation problem of CsPbBr quantum dots (QDs) in air are great challenges for their future practical application. Herein, a simple and effective ligand-modification strategy is proposed by introducing 2-hexyldecanoic acid (DA) with two short branched chains to replace oleic acid (OA) with long chains during the synthesis process. These two short branched chains not only maintain their colloidal stability but also contribute to efficient radiative recombination. The calculations show that CsPbBr QDs with DA modification (CsPbBr -DA QDs) have larger binding energy than CsPbBr QDs with OA (CsPbBr -OA QDs), resulting in significantly enhanced stability. Due to the strong binding energy between DA ligands and QDs, CsPbBr -DA QDs exhibit no aggregation phenomenon even after stored in air for more than 70 d, and CsPbBr -DA QDs films can maintain 94.3% of initial PL intensity after 28 d, while in CsPbBr -OA QDs films occurs a rapid degradation of PL intensity. Besides, the enhanced amplified spontaneous emission (ASE) performance of CsPbBr -DA QDs films has been demonstrated under both one- and two-photon laser excitation. The ASE threshold of CsPbBr -DA QDs films is reduced by more than 50% and their ASE photostability is also improved, in comparison to CsPbBr -OA QDs films.
CsPbBr量子点（QDs）在空气中稳定性差和存在聚集问题，这对其未来的实际应用构成了巨大挑战。在此，提出了一种简单有效的配体修饰策略，即在合成过程中引入具有两条短支链的2-己基癸酸（DA）来取代具有长链的油酸（OA）。这两条短支链不仅保持了它们的胶体稳定性，还有助于实现高效的辐射复合。计算结果表明，用DA修饰的CsPbBr量子点（CsPbBr -DA QDs）比用OA修饰的CsPbBr量子点（CsPbBr -OA QDs）具有更大的结合能，从而显著提高了稳定性。由于DA配体与量子点之间具有很强的结合能，CsPbBr -DA QDs即使在空气中储存70多天后也没有出现聚集现象，并且CsPbBr -DA QDs薄膜在28天后仍能保持初始PL强度的94.3%，而CsPbBr -OA QDs薄膜的PL强度则迅速下降。此外，在单光子和双光子激光激发下，CsPbBr -DA QDs薄膜的放大自发辐射（ASE）性能均得到了增强。与CsPbBr -OA QDs薄膜相比，CsPbBr -DA QDs薄膜的ASE阈值降低了50%以上，其ASE光稳定性也得到了提高。
