Dye Sensitization and Local Surface Plasmon Resonance-Enhanced Upconversion Luminescence for Efficient Perovskite Solar Cells.

Organic-inorganic hybrid perovskite solar cells (PSCs) have achieved rapid progress in this decade. However, the limited solar spectral utilization has restricted the further improvement of performance of the PSCs. One promising approach to solving this problem is utilizing IR to visible upconversion nanoparticles (UCNPs) in the PSC devices. Despite being confined by the lower quantum yield (QY) and smaller absorption cross section of the traditional UCNPs, their application is still a great challenge. In this work, the IR-783 dye-sensitized core/shell NaYF:Yb, Er@NaYF:Yb, and Nd UCNPs were synthesized and coupled with plasmonic Au nanorods films. Thereby, the upconversion luminescence (UCL) intensity was enhanced by about 120-fold, whereas the luminescent QY was improved from 0.2 to 1.2%. Then, the composite UCNPs were assembled on the SnO layer of the PSCs, which resulted in the power conversion efficiency (PCE) increasing from 19.4 to 20.5% under simulated 100 mw/cm AM 1.5G irradiation. Up to now, it is the highest PCE for the PSCs based on various upconversion devices. Under the irradiation of a sun concentrator (1 W/cm), the PCE of the device can be further improved to 21.1%. In-depth studies indicate that under standard sunlight irradiation, the improvement of PCE is due to both the IR to visible UCL and the scattering effect of the UCNPs. Under irradiation of a sun concentrator, the UCL contributes dominantly to the further improvement of PCE. This work provides an effective method for increasing the luminescent QY utilized in the PSCs and is of great significance for future PSCs that use sunlight concentrator.