Melamine-doped cathode interlayer enables high-efficiency organic solar cells

Abstract

Charge\ntransport, extraction, and collection play important roles\nin the working process of organic solar cells (OSCs), and the interface\nengineering is one of the key factors to realize the high-throughput\nprinting fabrication of OSCs. The structure design or doping of electrode\ninterlayer materials can effectively suppress the recombination of\ncarriers at the interface and improve the ohmic contact between the\nactive layer and the electrodes, which is a useful method to achieve\na high power conversion efficiency (PCE). Poly­(9,9-bis­(3′-(<i>N</i>,<i>N</i>-dimethyl)-<i>N</i>-ethylammoniumpropyl-2,7-fluorene)-<i>alt</i>-2,7-(9,9-dioctylfluorene))­dibromide (PFN-Br) is a widely\nused alcohol-soluble cathode interlayer material. By doping PFN-Br\nwith melamine (MA), the charge extraction efficiency and nongeminate\nrecombination at the cathode interface are successfully optimized.\nFinally, the device efficiencies of PM6:Y6 and PM6:BTP-eC9 are increased\nto an amazing 17.44% and 18.58%, respectively. This work provides\na new strategy for the fabrication of high-efficiency OSCs.