Morphology control via strategic halogen substitution achieving high-performance small-molecule based tandem solar cells exceeding 15% efficiency
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초록
내용
In this study, a series of benzodithiophene (BDT) based active materials with specific halogen atoms substituted were devised. In addition, how these halogen atoms affect the BHJ morphologies is demonstrated via microstructure analyses. The chlorine substituted one shows a well-mixed morphology and interpenetrating networks when blended with PC71BM, facilitating effective charge transportation. This controlled morphology helps achieve excellent performance with 10.5% power conversion efficiency (PCE) and the highest fill factor of 78.0% in the single-junction SM-SCs. It can also be extended to two-terminal (2T)-tandem solar cells, achieving an outstanding PCE of 15.1% via complementary absorption in the 2T-tandem solar cells that incorporate the SM-SCs. These results suggest that tailoring interactions with halogen atoms is an effective way to control BHJ architectures, thereby achieving remarkable performance in SM-SCs.