Bifunctional additive for defect passivation and conductivity improvement in carbon-based mesoscopic perovskite solar cells

Printable mesoscopic perovskite solar cells (MPSCs) are among the most promising commercial photovoltaic devices. The hole-conductor-free structure, however, posed a limitation in carrier transport and generated inevitable crystal defects, thereby adversely affecting further improvements in the efficiency and stability of MPSCs. Herein, a zwitterionic additive, namely, mafenide hydrochloride (MHCl) was introduced into MPSCs for defect passivation. In addition, MHCl can inhibit nonradiative recombination and extend carrier lifetimes to improve electrical conduction in the film. Consequently, the fabricated MPSC films show minimal hysteresis and enhancement of power conversion efficiency from 13.75 to 15.67%. The unencapsulated device showed remarkable stability, retaining 92% of its original power conversion efficiency (PCE) after storage for 80 days in the air with relative humidity (RH) of 50 +/- 5% at 25 +/- 5 degrees C.