Luminescent upconverting CsPbBr ₃ nanocrystals as spectral converter having chemodynamic potential against <i>Pseudomonas</i> bacteria

CsPbBr3 nanomaterials have wide application in photovoltaic areas. Judicious doping of Ln3+ ions in CsPbBr3 can enhance its capabilities as a spectral converter. In the present article, we hypothesized that the dopant has a pivotal role and can enhance the potential of CsPbBr3 beyond photovoltaic areas. Here, we have synthesized upconverting CsPbBr3:Er/Yb nanomaterials using an ionic liquid (IL)-assisted microwave (MW)-based method where 1-butyl 3-methyl imidazolium bromide ([C4mim]Br) IL was not only used as a templating agent but also a reaction partner. Green emission was observed from pure CsPbBr3 nanomaterials along with 78% photoluminescence quantum yield; however, when excited by 980 nm laser, green (545 nm) and intense red (654 nm) emissions were observed for CsPbBr3: Er3+/Yb3+ due to transitions of 2H11/2 + 4S3/2→ 4I15/2 and 4F9/2→4I15/2, respectively; however, no up-conversion emission is noticed from the tetragonal CsPb2Br5:Er3+/Yb3+ analog. Up-conversion emission intensity increases with Yb3+ ion concentration and reaches a maximum for CsPbBr3: Er3+ (1%)/Yb3+ (20%). Furthermore, we have demonstrated the chemodynamic potential of CsPbBr3 against Pseudomonas bacteria using hydrogen peroxide. We found significant bacterial cell death as a function of dopants. The mechanistic insight suggests the role of Fenton-like reactions in generating singlet oxygen, causing bacterial cell death.