Enhanced Performance and Stability of Q‐PHJ Devices through Strategic Placement of Dimerized Acceptors

Abstract Oligomeric acceptors are an effective π‐conjugate extension for small molecules because they effectively combine the advantages of polymeric and small molecular acceptors. The choice of linker group and oligomer position is however crucial for the efficient expression of π‐expansion advantages. Here, vinylene is chosen as the linker group and three oligomeric acceptors are produced with different connecting positions or end‐groups. Under illumination, the dimer acceptor dBTIC‐γV‐BO achieves the best power conversion efficiencies of 17.14% and a T₈₀ lifetime of 2150 h amongst quasi‐planar heterojunction devices, which are much higher and more stable than the directly connected dimers dBTICγ‐EH or dBTIC‐δV‐BO. These results indicate that the oligomerization of small molecules with an appropriate linker group in the γ‐position is an effective strategy with which to improve the photovoltaic performance and stability of organic solar cells, and significantly promote their commercialization.