Huang Xinyu, Chen Lan, Zhang Chunfeng, Qin Zhengyuan, Yu Buyang, Wang Xiaoyong, Xiao Min
National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China.
Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, United States.
J Phys Chem Lett. 2020 Dec 3;11(23):10173-10181. doi: 10.1021/acs.jpclett.0c03153. Epub 2020 Nov 16.
Perovskite semiconductor nanocrystals have emerged as an excellent family of materials for optoelectronic applications, where biexciton interaction is essential for optical gain generation and quantum light emission. However, the strength of biexciton interaction remains highly controversial due to the entangled spectral features of the exciton- and biexciton-related transitions in conventional measurement approaches. Here, we tackle the limitation by using polarization-dependent two-dimensional electronic spectroscopy and quantify the excitation energy-dependent biexciton binding energy at cryogenic temperatures. The biexciton binding energy increases with excitation energy, which can be modeled as a near inverse-square size dependence in the effective mass approximation considering the quantum confinement effect. The spectral line width for the exciton-biexciton transition is much broader than that for the ground state to exciton transition, suggesting weakly correlated broadening between these transitions. These inhomogeneity effects should be carefully considered for the future demonstration of optoelectronic applications relying on coherent exciton-biexciton interactions.
钙钛矿半导体纳米晶体已成为用于光电子应用的一类优秀材料，其中双激子相互作用对于光增益产生和量子光发射至关重要。然而，由于传统测量方法中激子和双激子相关跃迁的光谱特征相互纠缠，双激子相互作用的强度仍存在很大争议。在此，我们通过使用偏振相关二维电子光谱来解决这一限制，并在低温下量化激发能量相关的双激子结合能。双激子结合能随激发能量增加，在考虑量子限制效应的有效质量近似中，这可以建模为近乎反平方的尺寸依赖性。激子 - 双激子跃迁的光谱线宽比基态到激子跃迁的光谱线宽宽得多，表明这些跃迁之间存在弱相关展宽。对于未来依赖相干激子 - 双激子相互作用的光电子应用演示，应仔细考虑这些不均匀性效应。
