Regioisomer Engineering of Dimerized Small Molecule Acceptors for Efficient and Stable Organic Solar Cells
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초록
내용
The simultaneous achievement of a high‑power conversion efficiency (PCE) and long-term stability is essential for the commercialization of organic solar cells (OSCs). However, the thermal stability of OSCs based on small-molecule acceptors (SMAs) decreases because of morphological deterioration caused by the excessively fast diffusion of SMA molecules. In this study, two dimerized SMAs (DSMAs) comprising selenophene spacers with different regio-positions, DYSe-I and DYSe-O, are developed to achieve efficient and thermally stable OSCs. The different regio-positions in DSMAs have a substantial effect on various molecular properties. DYSe-I possesses a more planar backbone conformation and more continuously connected conjugation than DYSe-O. Consequently, DYSe-I exhibits a relatively higher crystallinity, electron mobility, and glass transition temperature. These favorable features of DYSe-I lead to a higher PCE and thermal stability in the resulting OSCs, surpassing those of the DYSe-O-based devices.