New self-doping alcohol-soluble polymer PDBND-FN as cathode interface layer enables efficient organic solar cells

Polymeric cathode interface materials that have self-doped characteristics have been widely investigated for use in organic solar cells (OSCs) to enhance the performance of the devices. Here, we designed and synthesized a new polymeric interfacial material PDBND-FN with self-doping effect. Subsequently, this novel material was successfully applied into OSCs with PTB7-Th:PC71BM as the active layer as the cathode interface layer (CIL), and the energy conversion efficiency of the device was improved from 8.53% to 9.43% compared to PFN. The self-doping properties were characterized by electron paramagnetic resonance, and PDBND-FN exhibited a more obvious free radical signal, indicating that PDBND-FN has great self-doping properties. The water contact angle and surface morphology of the active layer/PDBND-FN indicate that the surface polarity and smoothness of PDBND-FN were significantly improved. Therefore, the polymer PDBND-FN with self-doped properties can be used as a new interfacial material and offer an efficacious approach for the study of OSCs.