Zeng Peng, Ren Xinjian, Wei Linfeng, Zhao Haifeng, Liu Xiaochun, Zhang Xinyang, Xu Yanmin, Yan Lihe, Boldt Klaus, Smith Trevor A, Liu Mingzhen
School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu, 611731, China.
Key Laboratory of Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique, School of Electronic Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, China.
Angew Chem Int Ed Engl. 2022 Apr 4;61(15):e202111443. doi: 10.1002/anie.202111443. Epub 2022 Feb 15.
In photon-conversion processes, rapid cooling of photo-induced hot carriers is a dominant energy loss channel. We herein report a 3-fold reduced hot carrier cooling rate in CsPbBr nanocrystals capped with a cross-linked polysiloxane shell in comparison to single alkyl-chain oleylamine ligands. Relaxation of hot charge carriers depends on the carrier-phonon coupling (CPC) process as an important channel to dissipate energies in nanostructured perovskite materials. The CPC strengths in the two samples were measured through cryogenic photoluminescence spectroscopic measurements. The effect of organic ligands on the CPC in CsPbBr nanocrystals is elucidated based on a damped oscillation model. This supplements the conventional polaron-based CPC model, by involving a damping effect on the CPC from the resistance of the ligands against nanocrystal lattice vibrations. The model also accounts for the observed linear temperature-dependence of the CPC strength. Our work enables predictions about the effect of the ligands on the performance of perovskite nanocrystals in future applications.
在光子转换过程中，光生热载流子的快速冷却 是主要的能量损失通道。我们在此报告，与单烷基链油胺配体相比，用交联聚硅氧烷壳包覆的 CsPbBr 纳米晶体中的热载流子冷却速率降低了 3 倍。热电荷载流子的弛豫取决于载流子 - 声子耦合（CPC）过程，这是纳米结构钙钛矿材料中耗散能量的重要通道。通过低温光致发光光谱测量来测量两个样品中的 CPC 强度。基于阻尼振荡模型阐明了有机配体对 CsPbBr 纳米晶体中 CPC 的影响。这补充了传统的基于极化子的 CPC 模型，通过考虑配体对纳米晶体晶格振动的阻力对 CPC 的阻尼效应。该模型还解释了观察到的 CPC 强度的线性温度依赖性。我们的工作能够预测配体对未来应用中钙钛矿纳米晶体性能的影响。
