A series of polycyclic aromatic hydrocarbons (PAHs) with extended π-conjugated cores (from naphthalene, anthracene, pyrene, to perylene) are incorporated into nonfullerene acceptors for the first time. Four different fused-ring electron acceptors (FREAs), i.e., DTN-IC-2Ph, DTA-IC-3Ph, DTP-IC-4Ph, and DTPy-IC-5Ph, are prepared via simple and facile synthetic procedures, yielding a remarkable platform to study the structure–property relationship for nonfullerene solar cells. With the PAH core being extended systematically, the gradually redshifted absorption with enhanced molar extinction coefficient (ε) is realized, the energy level of the highest occupied molecular orbital is up-shifted, and the electron mobility is greatly enhanced. Meanwhile, the solubility decreases and the molecular packing becomes strengthened. As a result, with an optimized combination of these characteristics, DTP-IC-4Ph attains good solubility, high molar extinction coefficient, complementary absorption, suitable morphology, well-matched energy levels, as well as efficient charge dissociation and transport in blend film. Consequently, the DTP-IC-4Ph-based solar cells with a donor polymer, poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione))] (PBDB-T) exhibit a promising power conversion efficiency of 10.37% without any additives, which is close to the best performance achieved in additive-free nonfullerene solar cells (NFSCs). The results demonstrate that the PAH building blocks have great potential for the construction of novel FREAs for efficient additive-free NFSCs.
Bibliographical noteFunding Information:
Y.W. and B.L. contributed equally to this work. Y.W. acknowledges the financial support by the China Postdoctoral Science Foundation (Grant No. 2018M630267), the Natural Science Foundation of China (Grant No. 21805128), and the SUSTech Presidential Postdoctoral Fellowship. H.S. thanks the Natural Science Foundation of China (Grant No. 21801124). X.G. is grateful to Shenzhen Basic Research Fund (JCYJ20170817105905899) and Shenzhen Peacock Plan Project (KQTD20140630110339343). H.Y.W. thanks the financial support from the NRF of Korea (2016M1A2A2940911 and 2015M1A2A2057506). The authors are grateful to C. Hyun and Prof. T. J. Shin for the grazing-incidence X-ray scattering measurements.
© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- nonfullerene organic solar cells
- polycyclic aromatic hydrocarbon
- structure–property relationship
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)