Effect of Adding Cobalt Acetate on Performance of Fully Screen-Printable Perovskite Solar Cells

Controlling the crystal growth of perovskites by using additives is one of the effective ways to improve the performance of perovskite solar cells (PSCs). The effect of adding cobalt acetate on the crystal growth of perovskite and the performance of fully screen-printable hole-transport material (HTM)-free mesoporous PSCs with carbon electrode has been investigated. We found that addition of cobalt acetate to the perovskite precursor solution could efficiently increase the perovskite crystal size and improve the crystallinity and light absorption of perovskite films. PSCs fabricated with 4 mg/mL cobalt acetate added achieved the highest device performance, with open-circuit voltage of 0.96 V, short-circuit current density of 23.51 mA cm−2, fill factor of 0.66, and power conversion efficiency of 14.89%. The analysis results suggest that the improved device performance can be attributed to a decrease of nonradiative recombination and an increase of the charge recombination resistance with the addition of cobalt acetate.