Versatile Processability by Breaking the Symmetrical Chemical Structure of Nonfullerene Acceptors
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초록
내용
Despite the outstanding photovoltaic performance of symmetrical Y6, its use is limited in that only chloroform (CF), can induce favorable morphology. This dependence on a particular solvent poses an obstacle to the mass production. Herein, the effect of symmetry breaking of NFAs on device performance and processability using chlorobenzene (CB) or CF processing solvents is investigated. In organic solar cells (OSCs) based on a symmetrical Y6 acceptor, a significant difference in the power conversion efficiency (PCE) occurs between the OSCs fabricated using CB and those fabricated using CF. However, in OSCs based on NFA named IPC-BEH-IC2F with asymmetrical structure, no difference in photovoltaic performance occurs. GIWAXS measurements indicate that IPC-BEH-IC2F exhibits nearly identical diffraction features in both the CB- and CF-processed photoactive films, whereas Y6 shows markedly different stacking structures. The introduction of an asymmetrical structure can be an important strategy to enhance the versatile processability of OSCs based on NFAs for future mass production.