Manipulating the Intermolecular Interactions through Side Chain Engineering and Unilateral π‐Bridge Strategy for Efficient Small Molecular Photovoltaic Acceptor

Abstract

Thanks to the development of acceptor–donor–acceptor (A–D–A) type electron acceptors, organic solar cells (OSCs) have achieved marvelous progress in recent years. However, a systematic investigation about the structure–efficiency relationship is still highly desired to better understand the working mechanisms inside a bulk heterojunction (BHJ). In this study, new acceptors with the synergistic effect of side chain and unilateral π‐bridge strategy are designed, accounting for lower energy loss, expanded absorption, modulated intermolecular interactions and BHJ morphology. As a consequence, the resultant A–D–π–A acceptor ID‐C6Ph‐ST‐4F based binary solar cell receives an impressive efficiency up to 15.36%, much greater than the A–D–A analog ID‐C6Ph‐4F (10.75%), and ranks the best among all small molecular acceptors with symmetric or asymmetric π‐bridges. The results highlight the promising manipulation of phenylalkyl side chain and unilateral π‐bridge on intermolecular interactions among acceptor molecules and interactions between donor and acceptor (D/A) molecules. Superior interactions among acceptor molecules are an essential precondition to ensure preferable molecular assembly for charge transport, and meanwhile, moderately enhanced D/A interactions are also crucial for proper phase‐separation networks with efficient exciton dissociation and charge generation.

High performance polymerized small molecule acceptor by synergistic optimization on π-bridge linker and side chain

“…The very small χ values correspond to strong D/A interactions and excessive miscibility of the donor and acceptor (Fig. 4c ), which could raise the recombination losses 42 and result in lower J sc and FF of the all-PSCs. The χ da value of the PM6:PG-IT blend films is 0.37 K, which is larger than that of PY-IT.…”

Side-chain engineering improves molecular stacking and miscibility for efficient fullerene organic solar cells

“…Normally, the absorption edge of the active layers will be broadened by optimizing molecular aggregation via post-treatment. 44,45 According to the equation:…”

Thiophene–Perylenediimide Bridged Dimeric Porphyrin Donors Based on the Donor–Acceptor–Donor Structure for Organic Photovoltaics

“…The blend F-TPDI-2P active layer has a greater crystallinity than TPDI-2P, owing to its more rigid molecular planarity; however, the blend film F-TPDI-2P shows smaller phase domains than that of TPDI-2P-based blend film, which might be induced by the donor/acceptor interactions. This suggests that smaller phase domains could be helpful to reduce the bimolecular recombination loss and increase the donor/acceptor interfaces for efficient charge separation and generation at interfaces [phase images (bottom)], enabling us to record a decent FF of the solar cell. , …”