Chemical doping is an important approach to manipulating charge-carrier concentration and transport in organic semiconductors (OSCs)^1–3 and ultimately enhances device performance^4–7. However, conventional doping strategies often rely on the use of highly reactive (strong) dopants^8–10, which are consumed during the doping process. Achieving efficient doping with weak and/or widely accessible dopants under mild conditions remains a considerable challenge. Here, we report a previously undescribed concept for the photocatalytic doping of OSCs that uses air as a weak oxidant (p-dopant) and operates at room temperature. This is a general approach that can be applied to various OSCs and photocatalysts, yielding electrical conductivities that exceed 3,000 S cm^–1. We also demonstrate the successful photocatalytic reduction (n-doping) and simultaneous p-doping and n-doping of OSCs in which the organic salt used to maintain charge neutrality is the only chemical consumed. Our photocatalytic doping method offers great potential for advancing OSC doping and developing next-generation organic electronic devices.

The power conversion efficiencies (PCEs) of single‐junction organic solar cells (OSCs) have surpassed 19%, owing to the emerging Y‐series nonfullerene acceptors (NFAs). Undoubtedly, the power and flexibility of chemical design has been a strong driver for this rapid efficiency improvement in the OSC field. Over the course of the past 3 years, a variety of modifications have been made to the structure of the Y6 acceptor, and a large number of Y‐series NFAs have been reported to further improve performance. Herein, we present our insights into the rationale behind the Y6 acceptor and discuss the design principles toward high‐performance Y‐series NFAs. It is clear that structural modifications through choice of heteroatom, soluble chains, π spacers, central cores, and end groups alter the material characteristics and properties, contributing to distinctive photovoltaic performance. Subsequently, we analyze various design strategies of Y‐series‐containing materials, including polymerized small‐molecule acceptors (PSMA), non‐fused‐ring acceptors (NFRA), and all‐fused‐ring acceptors (AFRA). This review is expected to be of value in providing effective molecular design strategies for high‐performance NFAs in future innovations.

A series of perylene diimide (PDI) dimers (PnTP, n = 0–3) with oligothiophenes as bridges were designed, theoretically calculated, synthesized, and developed as electron acceptors for polymer solar cells (PSCs). The effects of oligothiophene bridge length on the absorption, energy level, charge transport, morphology and photovoltaic properties of the molecules were investigated. These molecules exhibited good thermal stability with decomposition temperatures of 367–413 °C, broad and strong absorption in the visible region (400–700 nm), and appropriate HOMO (−5.74 to −5.61 eV) and LUMO (−3.84 to −3.72 eV) energy levels. When blending these PDI acceptors with a low bandgap polymer donor PBDTTT-C-T, the PSCs exhibited power conversion efficiencies of 0.76–3.61%.