Dual‐Function NaYF4 : Yb3+/Er3+ Boosts Efficiency for Multi‐Dye Sensitized Solar Cells and Carbon‐Based CsPbI2Br Perovskite Solar Cells

Abstract Enhanced power conversion efficiency (PCE) is witnessed by inclusion of dual function NaYF 4 : Yb 3+ /Er 3+ as photon upconverter (UC) and light scatterer (LS) for dye sensitized solar cells (DSSCs), as well perovskite solar cells (PSCs). Emission studies by excitation with 980 nm laser light and diffuse reflectance measurements confirm that the synthesized NaYF 4 : Yb 3+ /Er 3+ exhibits dual function as upconverter and light scatterer. Three emission bands, in the spectral range of 650–710 nm, 510–570 nm, and 400–420 nm, are witnessed in emission studies. Multi‐dye (N719, N749 and SPSQ2 dyes) sensitization is introduced during photoelectrode preparation. The absorption spectra match the observed emission bands well. The combined upconversion, light scattering and multi‐dye sensitized DSSC reveals a high PCE of 11.16 %. The achieved results encouraged the fabrication of a PSC and its mini solar cell module by use of cost‐effective carbon as electrode and all‐inorganic CsPbI 2 Br perovskite. The results reveal PCEs of 16.55 % and 11.82 %, respectively.