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arXiv · 2206.13716

Lattice distortion inducing exciton splitting and coherent quantum beating in CsPbI3 perovskite quantum dots

Yaoyao Han·Wenfei Liang·Xuyang Lin·Yulu Li·Fengke Sun·Fan Zhang·Peter C. Sercel·Kaifeng Wu
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Abstract

Anisotropic exchange-splitting in semiconductor quantum dots (QDs) results in bright-exciton fine-structure-splitting (FSS) important for quantum information processing. Direct measurement of FSS usually requires single/few QDs at liquid-helium temperatures, because of its sensitivity to QD size and shape, whereas measuring and controlling FSS at an ensemble-level seem to be impossible unless all the dots are made to be nearly the same. Here we report strong bright-exciton FSS up to 1.6 meV in solution-processed CsPbI3 perovskite QDs, manifested as quantum beats in ensemble-level transient absorption at liquid-nitrogen to room temperatures. The splitting is robust to QD size and shape heterogeneity, and increases with decreasing temperature, pointing towards a mechanism associated with orthorhombic distortion of perovskite lattice. Effective-mass-approximation calculations reveal an intrinsic "fine-structure gap" that agrees well with the observed FSS. This gap stems from an avoided crossing of bright-excitons confined in orthorhombically-distorted QDs that are bounded by the pseudocubic {100} family of planes.

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Yaoyao Han, Wenfei Liang, Xuyang Lin, Yulu Li, Fengke Sun, Fan Zhang, Peter C. Sercel, Kaifeng Wu. 2022-06-28. Lattice distortion inducing exciton splitting and coherent quantum beating in CsPbI3 perovskite quantum dots. https://doi.org/10.1038/s41563-022-01349-4

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