You are cordially invited to the SCL seminar of the Center for the Study of Complex Systems, which will be held on Thursday, 2 October 2025 at 14:00 in the "Zvonko Marić" lecture hall of the Institute of Physics Belgrade. The talk entitled

Electronic properties of perovskite nanocrystals

will be given by Milan Jocić (SCL, Institute of Physics Belgrade). The abstract of the talk:

Over the past decade, halide perovskites have emerged as excellent candidates for photovoltaic applications due to their low cost and high performance. However, obtaining reliable and accurate electronic properties from ab initio methods requires a proper description of their electronic structure. The most critical parameter in this structure is the band gap of the bulk material, which cannot be reproduced using conventional DFT with local or semi-local functionals. Hybrid functionals with full spin–orbit treatment offer some improvement but still underestimate the electronic band gap in these materials. In this talk, we focus on the electronic structure of halide perovskites with the formula CsPbX3 (X = Cl, Br, I) and the theoretical methods used to obtain it.

First, we investigate the bulk material and propose a combination of DFT with the hybrid PBE0 functional, along with the Allen–Heine–Cardona (AHC) method, to evaluate temperature-dependent band renormalization arising from electron–phonon interactions. To achieve this, the calculation of anharmonic phonon frequencies using the self-consistent phonon method was necessary, instead of relying on the standard DFPT procedure. We further propose a way to simultaneously treat energy renormalization and broadening by employing a self-consistent Migdal approximation. This procedure allows us to obtain the renormalization of any band at any point in the Brillouin zone and can be extended to crystals with similar structures [1].

Next, we combine results from our previous work [2], which describes the construction of symmetry-adapted Hamiltonians from ab initio methods for both bulk and nanocrystals. Using the temperature-dependent band structure obtained for the bulk, we extend the approach to nanocrystals of various shapes, including quantum wells, wires, and dots.

[1] M. Jocić and N. Vukmirović, Phys. Chem. Chem. Phys., 2023, 25, 29017–29031.
[2] M. Jocić and N. Vukmirović, Phys. Rev. B, 2020, 102, 085121.