Impact of Host Composition, Codoping, or Tridoping on Quantum-Cutting Emission of Ytterbium in Halide Perovskite Quantum Dots and Solar Cell Applications.

Recently, various lanthanide ions (Ln3+) have been successfully doped into perovskite quantum dots (PQDs), and the quantum-cutting emission of 2F5/2-2F7/2 for Yb3+with a measurable inner efficiency of more than 100% has been discovered and applied as the luminescent converter of solar cells, which has opened a new branch for the application of PQDs. In this work, to further improve the quantum-cutting efficiency of Yb3+, the codoping and tridoping methods were used to improve the quantum-cutting emission of PQDs. The Yb3+-Ln3+ (Ln = Nd, Dy, Tb, Pr, Ce) pair-doped CsPbClxBryI3-x-y PQDs were fabricated, with all displaying excitonic emission, narrow-band emission of Ln3+ ions, and quantum-cutting emission of Yb3+ ions. It was interesting that Yb3+-Pr3+ as well as Yb3+-Ce3+ pairs could effectively sensitize the emission of Yb3+, owing to Pr3+ and Ce3+ ions offering intermediate energy states close to the exciton transition energy of the PQDs. After host composition optimization and tridoping investigation, overall emissions with a 173% photoluminescence quantum yield (PLQY) were obtained in the Yb3+-Pr3+-Ce3+-tridoped CsPbClBr2 PQDs. Then, the tridoped PQDs were designed as the down-converter for CuIn1-xGaxSe2 (CIGS) as well as the silicon solar cells, which leads to an enhancement of the power conversion efficiency (PCE) of as high as ∼20%. The modified CIGS was further employed to charge the smart mobile phone, which could largely shorten the charging time from 180 to 150 min. This finding is of great significant for expanding the application fields of the impurity-doped PQDs.