All-order correlation of single excitons in nanocrystals using ak·penvelope-function approach: Application to lead halide perovskites

The authors revisit the theory of strongly correlated excitons confined in semiconductor nanocrystal quantum dots, motivated by recent experiments on nanocrystals of all-inorganic cesium lead halide perovskites (e.g., CsPbBr${}₃$), which have outstanding optoelectronic properties. Using a variety of $\mathbf{k}\ensuremath{\cdot}\mathbf{p}$ many-body approaches, including many-body perturbation theory, configuration interaction, the Bethe-Salpeter equation, and the random-phase approximation with exchange, they show that the strong correlation arises exclusively from the all-order summation of particle-hole ladder diagrams, as in the bulk, although finite-size effects are substantial.