Over 14% Efficiency Single‐Junction Organic Solar Cells Enabled by Reasonable Conformation Modulating in Naphtho[2,3‐b:6,7‐b′]difuran Based Polymer

Abstract As one kind of abundant product from renewable resources, furan and its fused‐ring derivatives, have provoked great interest in the context of developing efficient photovoltaic materials. However, the power conversion efficiency (PCE) of furan‐based photovoltaic materials has lagged behind its thiophene counterparts. In this work, in consideration of the ordered π–π stacking via extending conjugation to further improve the charge mobility, a novel furan fused‐ring derivative of naphtho[2,3‐b:6,7‐b′]difuran (NDF) based copolymer of NDF‐3T is designed and synthesized. Because of its favorable linear molecular conformation, the NDF‐3T possesses a high crystallinity, as well as ordered and dense π–π stacking. Subsequently, the NDF‐3T‐based device exhibits an efficient PCE of 14.21%, which is higher than that of the analogue naphthodithiophene (NDT) counterpart (10.86%). To the best of the authors’ knowledge, the PCE is also the best record in furan‐based photovoltaic materials. More importantly, the development of line NDF shows great potential in construing highly efficient photovoltaic materials and can be referenced to other furan fused‐ring structures.