Zhang Yan-Xia, Wang Hai-Yu, Zhang Zhen-Yu, Zhang Yu, Sun Chun, Yue Yuan-Yuan, Wang Lei, Chen Qi-Dai, Sun Hong-Bo
State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China.
Phys Chem Chem Phys. 2017 Jan 18;19(3):1920-1926. doi: 10.1039/c6cp04083g.
Recently, all-inorganic cesium lead halide perovskites (CsPbX) quantum dots (QDs) have attracted great attention due to their halogen composition and size tunable band gap engineering, the same physical mechanism that is responsible for excellent performance in light-emitting devices. However, little is known about the time-resolved fluorescence quenching dynamics process of these CsPbX QDs. In this article, we present comprehensive contrastive spectral studies on the electron and hole extraction dynamics of CsPbX colloidal QDs with and without quencher by time-resolved femtosecond transient absorption (TA) and time-correlated single-photon counting (TCSPC) spectroscopy methods. We have identified that the partial electrons of the conduction band and holes of the valence band of CsPbX QDs can be directly extracted by tetracyanoethylene (TCNE) and phenothiazine (PTZ), respectively. Moreover, compared with the CsPbBr QDs, the CsPbI QDs showed relatively slower charge extraction rates. We also found that the CsPbBr QDs with smaller size showed faster carrier recombination rates and photoluminescence (PL) decay lifetime due to the relatively stronger quantum confinement effects. We believe that this study may be useful for realising optimal applications in photovoltaic and light emission devices.
最近，全无机铯铅卤化物钙钛矿（CsPbX）量子点（QDs）因其卤素组成和尺寸可调的带隙工程而备受关注，这与发光器件优异性能所基于的物理机制相同。然而，对于这些CsPbX量子点的时间分辨荧光猝灭动力学过程，人们了解甚少。在本文中，我们通过时间分辨飞秒瞬态吸收（TA）和时间相关单光子计数（TCSPC）光谱方法，对有猝灭剂和无猝灭剂的CsPbX胶体量子点的电子和空穴提取动力学进行了全面的对比光谱研究。我们已经确定，CsPbX量子点导带的部分电子和价带的空穴可以分别被四氰基乙烯（TCNE）和吩噻嗪（PTZ）直接提取。此外，与CsPbBr量子点相比，CsPbI量子点的电荷提取速率相对较慢。我们还发现，尺寸较小的CsPbBr量子点由于相对较强的量子限制效应，显示出更快的载流子复合速率和光致发光（PL）衰减寿命。我们相信这项研究可能有助于实现光伏和发光器件的最佳应用。
