Tetramerized Small-Molecule Acceptor for Organic Solar Cells with Enhanced Efficiency, Stability and Mechanical Robustness: Impact of Chain Length and Dispersity Effects
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초록
내용
Discrete oligomer acceptors have enhanced the stability of organic solar cells (OSCs) due to their slow diffusion kinetics from their large molecular sizes. However, development of multimer acceptors with chain length longer than trimers has been challenging, which often require multi-step reactions with low synthetic yield. In this study, we develop a new tetramerized acceptor (TetA) using one-pot reaction and subsequent purification. The OSCs for TetA demonstrate a higher power conversion efficiency (PCE) of 16% than those for the monomer (MA), dimer (DA) and trimer (TA) acceptors (13–15%). Additionally, despite having a similar number-average molecular weight, TetA-based OSCs exhibit a higher PCE (16%) than the OSCs based on a mixture of the acceptors (MixA) with dispersity (11%). Furthermore, the TetA-based OSCs have the highest photostability and mechanical robustness among the series, highlighting importance of chain length and dispersity in oligomer acceptors.