Direct, Indirect, and Self-Trapped Excitons in Cs 2 AgBiBr 6 .

Autor: Baskurt M; Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden., Erhart P; Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden., Wiktor J; Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
Jazyk: angličtina
Zdroj: The journal of physical chemistry letters [J Phys Chem Lett] 2024 Aug 22; Vol. 15 (33), pp. 8549-8554. Date of Electronic Publication: 2024 Aug 13.
DOI: 10.1021/acs.jpclett.4c01604
Abstrakt: Cs 2 AgBiBr 6 exhibits promising photovoltaic and light-emitting properties, making it a candidate for next-generation solar cells and LED technologies. Additionally, it serves as a model system within the family of halide double perovskites, offering insights into a broader class of materials. Here, we study various possible excited states of this material to understand its absorption and emission properties. We use time-dependent density functional theory (TD-DFT) coupled with nonempirical hybrid functionals, specifically PBE0(α) and dielectric-dependent hybrids (DDH) to explore direct, indirect, and self-trapped excitons in this material. Based on comparison with experiment, we show that these methods can give excellent predictions of the absorption spectrum and that the fundamental band gap has been underestimated in previous computational studies. We connect the experimental photoluminescence signals at 1.9-2.0 eV to the emission from self-trapped excitons and electron polarons. Finally, we reveal a complex landscape with energetically competing direct, indirect, and self-trapped excitons in the material.
Databáze: MEDLINE