Graphene-modified CoOx hole transport layers for efficient ambient-air-processed perovskite solar cells

Abstract

Owing to their distinctive characteristics, perovskite solar cells have attracted considerable attention in recent years. The function of perovskite solar cells depends substantially on the charge transport layers (CTLs). Thus, the selection of an appropriate and cost-effective CTL is essential. Although cobalt oxide has great promise as an inverted PSC hole-injecting film, CoOx needs to meet the performance demands. In inverted-type CoOx-based perovskite solar cells, the most significant hurdle to achieving improved power conversion efficiencies is the weak conductivity of cobalt oxide hole carriers. The purpose of this work is to employ a graphene-based additive to improve the conductivity of traditional cobalt oxide films. Throughout the precursor development process, graphene nanoplatelets (GNP) were incorporated into the cobalt oxide solution. Sol–gel approaches were utilized to fabricate the whole solar cells out of glovebox under ambient air with a configuration of ITO/CoOx/CH3NH3PbI3/PCBM/BCP/Ag. The findings indicated that GNP improved power conversion efficiency (PCE) by enhancing open-circuit voltages and short-circuit current densities. According to long-term stability testing, graphene-modified cells maintained 70% of their initial PCE after 480 h, whereas the unmodified cells decreased to 43%. These behaviors are associated with a decreased VTFL value from the space charge limited current method.