Lattice distortion inducing exciton splitting and coherent quantum beating in CsPbI3 perovskite quantum dots
arXiv:2206.13716 · doi:10.1038/s41563-022-01349-4
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.
References in corpus (6)
- Entangled Photon Pairs from Semiconductor Quantum Dots
- Coherent Single Photon Emission from Colloidal Lead Halide Perovskite Quantum Dots
- The impact of the halide cage on the electronic properties of fully inorganic caesium lead halide perovskites
- Ultrafast Manipulation of Valley Pseudospin
- Coherent Spin Precession and Lifetime-Limited Spin Dephasing in CsPbBr3 Perovskite Nanocrystals
- Quantum Interference in a Single Perovskite Nanocrystal