Efficient printable mesoscopic perovskite solar cells without post thermal-annealing processes by introduction of a volatile co-solvent

Abstract

To improve the power conversion efficiency (PCE) of printable mesoporous perovskite solar cells (p-MPSCs) without post thermal-annealing processes, a multi-solvent system is employed in the perovskite precursor solution, using tetrahydrofuran (THF) as a volatile co-solvent and N-hexyl-2-pyrrolidone (CHP) as a coordinating solvent. In situ polarized light microscope images and in situ photoluminescence spectra indicate that the multi-solvent system can finely tune the chemical environment in the precursor solution, allowing for rapid nucleation during the growth of the perovskite film while extending the time for crystal growth, thus optimizing the crystallization process of the perovskite film. The power conversion efficiency (PCE) of the p-MPSCs based on the optimized multi-solvent system increased from 16.39% for the reference device to 18.29%. The stability of p-MPSCs based on the multi-solvent system was also significantly improved compared to reference devices, with unencapsulated p-MPSCs retaining 93.3% of their initial PCE after being stored for 208 days under ambient conditions.