Title: Excitons in halide double perovskites and the limits of the Wannier-Mott model in heterogeneous semiconductors
Speaker: Linn Leppert (UT, Computational Chemical Physics)
Time: April 21, 2022, 10:00–11:00
Location: Hybrid: TU/e (Flux 1.124) and online (MS Teams)
Abstract: Halide double perovskites are an emerging class of photoactive materials with considerable structural and electronic diversity and reliable stability towards heat and moisture under ambient conditions. However, little is known about their excitonic properties; whether simple physically motivated exciton models like the Wannier-Mott model are reliable for these quaternary, heterogeneous materials, is hard to predict a priori. In this talk I will discuss how first principles numerical modelling techniques can provide an atomistic understanding of excitons in halide double perovskites. I will show that these materials can feature a wide range of excitons, with binding energies spanning several orders of magnitude. Whether these excitons fall into the tenets of the Wannier-Mott model is determined by the symmetry and orbital character of their band edges – a consequence of their chemical heterogeneity.