Colloidal CsCu5S3 nanocrystals as an interlayer in high-performance perovskite solar cells with an efficiency of 22.29%

The ionic nature of perovskites leads to abundant defects at the interface and grain boundaries of perovskite films, which are detrimental to the performance of perovskite solar cells (PSCs). Here, I-I-VI group CsCu 5 S 3 (CCS) nanocrystals (NCs) were used as an interlayer between the perovskite film and hole transport layer in PSCs. The CCS NCs were synthesized via a facile colloidal chemistry approach and exhibited high air stability and strong absorption in the visible-to-near infrared range. The CCS interlayer effectively passivates the interfacial defects, which strongly suppresses non-radiative recombination in the PSCs. The CCS interlayer is favorable for energy levels between the perovskite and HTM to reduce carrier recombination. As a result, the devices with a CCS interlayer delivered a champion power conversion efficiency (PCE) of 22.29% with good reproducibility and stability. In addition, the PSCs retained more than 85% of their original efficiency after storage for approximately 3000 h under ambient conditions. This work paves a new avenue for the development of high-efficiency PSCs and the application of Cu-based chalcogenide NCs.