Toward High‐Performance Semitransparent Organic Photovoltaics with Narrow‐Bandgap Donors and Non‐Fullerene Acceptors

Abstract Solar energy offers an alternative solution to the global community's growing energy demands. Semitransparent organic photovoltaics (ST‐OPVs) have received tremendous attention due to their tunable energy levels and rising power conversion efficiency (PCE). Because of its transparency, ST‐OPVs are able to serve as the power‐generating roof of the greenhouse, and color‐tunable walls/windows for modern buildings or façades. With the rapid development of narrow‐bandgap semiconductors to absorb near‐infrared photons, the performances of ST‐OPVs has progressed with PCEs over 12% with average visible transmittances over 20%. Here, recent developments in ST‐OPVs based on narrow‐bandgap donors and non‐fullerene acceptors are reviewed. Several strategies for chemical structures design have been reported to lower bandgaps semiconductor materials. The recent developments of non‐fullerene acceptor structures for ST‐OPVs are categorized into A‐D‐A, A‐π‐D‐π‐A, and A‐DAD‐A by the structure alignment. From device perspectives, the strategies such as ternary blend, distributions of donors and acceptors in active layers, tandem and transparent conductive electrodes for high‐performance ST‐OPVs are summarized. To conclude, some insightful guidelines for future developments in ST‐OPVs from both materials and device points of views are provided.