About the seminar:

Metastable phases of multinary metal chalcogenide nanoparticles (NPs) are promising materials for thin film photovoltaics. The rational synthesis design of these metastable phases is a current challenge in the field as little is known about the exact mechanism and formation of many of these materials. This paper, Band Gap Engineering and Metastable Phase Discovery in Cu₂BaSnS_4−xSe_x Nanocrystals via Topotactic Anion Exchange by Sun et al. presents a well-rounded approach and study of the formation of metastable trigonal Cu₂BaSnSe₄ (CBTSe) NPs. The trigonal phase of CBTSe NPs is calculated to have a lower band gap than the stable orthorhombic phase CBTSe NPs. Sun et al. presents a synthesis route for metastable trigonal CBTSe NPs that display properties consistent with their hypotheses: a topotactic anion exchange can stabilize the metastable trigonal phase.