Abstract
The flexibility in structural design of organic semiconductors endows organic solar cells (OSCs) not only great function-tunabilities, but also high potential toward practical application. In this work, simple non-fused-ring electron acceptors are developed through two-step synthesis from single aromatic units for constructing efficient OSCs. With the assistance of non-covalent interactions, these rotatable non-fused acceptors (in solution) allow transiting into planar and stackable conformation in condensed solid, promoting acceptors not only feasible solution-processability, but also excellent film characteristics. As results, decent power conversion efficiencies of 10.27% and 13.97% can be achieved in single and tandem OSCs consisting of simple solution-cast blends, in which the fully unfused acceptors exhibit exceptionally low synthetic complexity index. In addition, the unfused acceptor and its based OSCs exhibit promising stabilities under continuous illumination. Overall, this work reveals valuable insights on the structural design of simple and effective electron acceptors with great practical perspectives.
Highlights
The flexibility in structural design of organic semiconductors endows organic solar cells (OSCs) great function-tunabilities, and high potential toward practical application
Through theoretical and experimental investigations, we reveal that non-fused-ring acceptors (NFRAs) with rotatable conformation in solution could be restrained into planar and stackable conformation in condensed solid
The synthetic complex (SC) index of these NFRAs was calculated according to reported methodologies[24,34], wherein the SC index of PTIC is around 55%, much smaller than that of ID4F (97%) and other compared fused-ring electron acceptor (FREA) (Supplementary Table 1)
Summary
The flexibility in structural design of organic semiconductors endows organic solar cells (OSCs) great function-tunabilities, and high potential toward practical application. The synthetic complexities of the molecule are inversely proportional to the industrial figure of merit for OSCs24,26, since multi-step synthesis and purification rapidly increase the material costs These issues would potentially undermine the practical perspectives of OSCs. despite a large family of electron acceptors developed, there is still a strong need to explore the new structural design of simple and effective molecules, for accessing efficient and low-cost OSCs. despite a large family of electron acceptors developed, there is still a strong need to explore the new structural design of simple and effective molecules, for accessing efficient and low-cost OSCs Bearing this in mind, electron acceptors with partially[17,27,28,29] or fully unfused backbones[30], have recently been explored, wherein the noncovalent intramolecular interactions[29,31,32,33] are employed to mediate the planarity of these molecular structures. If performance insufficiency is overcome, efficient OSCs with easy accessibility of key active components could be expected
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