Rashba Exciton in a 2D Perovskite Quantum Dot

The Rashba effect has been proposed to give rise to a bright exciton ground state in halide perovskite nanocrystals (NCs), resulting in very fast radiative recombination at room temperature and extremely fast radiative recombination at low temperature. [1] In this work we find the dispersion of the "Rashba exciton", i.e., the exciton whose bulk dispersion reflects large spin-orbit Rashba terms in the conduction and valence bands and thus has minima at non-zero quasi-momenta. [2] Placing Rashba excitons in quasi-2D cylindrical quantum dots, we calculate size-dependent levels of confined excitons and their oscillator transition strengths. We consider the implications of this model for two-dimensional hybrid organic-inorganic perovskites, discuss generalizations of this model to 3D NCs, and establish criteria under which a bright ground exciton state could be realized.<br/>[1] <i>Nature</i> <b>553</b>, 189 (2018) DOI: 10.1126/science.aau7392<br/>[2] <i>Nanoscale</i> <b>13</b>, 16769 (2021) DOI: 10.1039/d1nr04884h