Lattice distortion in lead halide perovskite quantum dots leads to a great structure space and meaningful exciton quantum beating. Credit: DICP
Researchers just reported the usage of lattice distortion in lead halide perovskite quantum dots to control their exciton great structure. The scientists were led by Prof. Kaifeng Wu from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), in cooperation with Dr. Peter C. Sercel from the Center for Hybrid Organic Inorganic Semiconductors for Energy (CHOISE). CHOISE is an Energy Frontier Research Center (EFRC) of the U.S. Department of Energys Office of Science.
The research study was published in Nature Materials on September 8, 2022.
It is well established that shape or crystal anisotropy in quantum dots, which are tiny semiconductor nanoparticles, results in energy splitting of their optically intense excitons (bound electron-hole pairs). This is called fine structure splitting (FSS). These excitons form a crucial play area for quantum information science researchers. For circumstances, the excitons FSS can be exploited for coherent control of quantum states for quantum computing, or for polarization-entangled photon sets in quantum optics, although for the latter it is very important to reduce the magnitude of splitting.
Generally, studying FSS typically needs a single or just a couple of quantum dots at liquid-helium temperature, due to the fact that of its level of sensitivity to quantum dot size and shape. Determining FSS at an ensemble level, not to mention managing it, appears difficult unless all the dots are made to be nearly similar.
In this study, by using ensemble-level femtosecond polarized transient absorption, the scientists observed clear bright-exciton FSS in solution-processed CsPbI3 perovskite quantum dots, which is manifested as exciton quantum beats (periodic oscillations of kinetic traces).
” Even more amazingly, the beat frequency, as figured out by the FSS energy, of a provided sample can be continuously managed by changing the temperature. This is an unmatched result, indicating that now scientists can facilely control FSS through temperature level,” stated Prof. Wu.
The researchers also discovered that the temperature-dependent FSS was related to the fascinating, highly-dynamic lattice of lead halide perovskites. Decreasing the temperature led to a more distorted lead-iodide octahedral structure.
Estimations recommended that, because these orthorhombic-phase quantum dots were really still bounded by the pseudocubic household of crystal planes, the lattice distortion results in a prevented crossing fine-structure space in between bright exciton. This gap was responsible for the observed FSS, and it might be detected in spite of quantum dot size and shape heterogeneity throughout an ensemble sample.
” Lattice distortion in CsPbI3 perovskites is popular in the photovoltaic community, as it is linked to the issue of phase stability of perovskite solar cells, but nobody has actually previously connected it experimentally to the exciton great structure,” said Prof. Wu. “Our research study demonstrates that this material residential or commercial property can actually be utilized to control the bright-exciton splitting in quantum dots for quantum infotech.”
Recommendation: “Lattice distortion causing exciton splitting and meaningful quantum whipping in CsPbI3 perovskite quantum dots” by Yaoyao Han, Wenfei Liang, Xuyang Lin, Yulu Li, Fengke Sun, Fan Zhang, Peter C. Sercel and Kaifeng Wu, 8 September 2022, Nature Materials.DOI: 10.1038/ s41563-022-01349-4.
By Dalian Institute of Chemical Physics, Chinese Academy Sciences
September 9, 2022
Researchers just reported the utilization of lattice distortion in lead halide perovskite quantum dots to control their exciton fine structure. It is well developed that shape or crystal anisotropy in quantum dots, which are small semiconductor nanoparticles, results in energy splitting of their optically intense excitons (bound electron-hole pairs). These excitons form a crucial play ground for quantum info science researchers. The excitons FSS can be exploited for coherent control of quantum states for quantum computing, or for polarization-entangled photon pairs in quantum optics, although for the latter it is essential to reduce the magnitude of splitting.