Crucial role of fluorine in fully alkylated ladder type carbazole based nonfullerene acceptors for efficient organic solar cells

Published

January 30, 2020

Author(s)

Eliot Gann, Christopher McNeill, He Qiao, Munazza Shahid, Xuchem Jiao, Flurin D. Eisner, Tingmang Wu, Zhuping Fei, Thomas D. Anthopoulos, Martin Heeney

Abstract

Two fused ladder type nonfullerene acceptors, DTCCIC and DTCCIC-4F, based on an electron-donating core alkylated dithienocyclopentacarbazole flanked by electron-withdrawing non-fluorinated or fluorinated 1,1- dicyanomethylene-3-indanone (IC or IC-4F), are designed, synthesized, and applied in organic solar cells (OSCs). The two new molecules reveal planar structures and strong aggregation behavior. OSCs based on DTCCIC-4F exhibit a power conversion efficiency of 12.6%, much higher than that of DTCCIC based devices (6.2%). Microstructural studies reveal that while both acceptors are highly crystalline, bulk heterojunction blends based on the non- fluorinated DTCCIC result in overly coarse domains, while blends based on the fluorinated DTCCIC- 4F exhibit a more optimal nanoscale morphology. Our results demonstrate that fluorine in DTCCIC-4F can help balance molecular aggregation that leads to efficient charge separation and mobility, but not so excessive that leads to excessive phase separation, which is crucial to achieve high performance OSCs.

Citation

ACS Applied Materials and Interfaces

Pub Type

Journals

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Keywords

Solar Cells, RSoXS, resonant scattering

Citation

Gann, E. , McNeill, C. , Qiao, H. , Shahid, M. , Jiao, X. , Eisner, F. , Wu, T. , Fei, Z. , Anthopoulos, T. and Heeney, M. (2020), Crucial role of fluorine in fully alkylated ladder type carbazole based nonfullerene acceptors for efficient organic solar cells, ACS Applied Materials and Interfaces, [online], https://doi.org/10.1021/acsami.0c00981 (Accessed May 2, 2024)