Improving upconversion efficiency of NaLuF4:Yb,Er by doping Gd3+ and application for perovskite solar cells.

The use of upconversion (UC) materials is an effective strategy for harvesting the near-infrared (NIR) solar photons in perovskite solar cells. Hexagonal β-NaLuF₄:Yb,Er submicron prisms were synthesized by a facile solvothermal method. Gd³⁺ doping is used to enhance the UC emission intensity. We investigated how the concentration of Gd³⁺ ions affected the morphological evolution, microstructure, and luminescence performance of NaLuF₄:Yb,Er and explored the mechanism for improving luminescence at 980 nm excitation. By incorporating the optimized NaLuF₄:Yb,Er,Gd into the perovskite solar cells' (PSCs) hole transport layer, the short-circuit density (J_sc) of UC-PSCs can be enhanced from 19.31 to 21.77 mA cm⁻². [ABSTRACT FROM AUTHOR]