2021 Adv. Mater. (IF 30.849), ASM-OSC with 16.2% PCE & 75.6% FF

　　Advanced Materials (IF 30.849) published a research result in November 2021. Harald Ade of North Carolina State University, Zhixiang Wei of Nanoscience Center and others made the efficiency of all-small-molecule organic solar cells (ASM-OSC) reach 16.2% through the high miscibility of ordered molecular packing.

　　Compared with polymer solar cells (PSCs), all-small-molecule organic solar cells (ASM-OSCs) composed of small molecule donors and small molecule acceptors can be processed in solution. The relationship between their molecular structures and device performance were even greater and easy to build. In ASM-OSC, high short-circuit current (J_sc) usually uses small phase separation, and high fill factor (FF) is usually achieved in highly ordered stacking systems. However, the two always conflict with each other and restrict J_sc and FF.

　　In order to alleviate this dilemma, the research team proposed to obtain good miscibility and ordered packing by adjusting the interaction of the same and different molecules. They moved the alkylthiolated side chain in the small molecule donor from the para position to the meta position and developed two new types of small molecule donors: P-PhS and M-PhS. At this time, the surface tension of the donor and the planarity of the molecule were simultaneously enhanced and produced good miscibility and strong self-assembly ability with the acceptor BTP-eC9.