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

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.