標題: Isomerically Pure Benzothiophene-Incorporated Acceptor: Achieving Improved V-oc and J(sc) of Nonfullerene Organic Solar Cells via End Group Manipulation
作者: Chang, Shao-Ling
Hung, Kai-En
Cao, Fong-Yi
Huang, Kuo-Hsiu
Hsu, Chain-Shu
Liao, Chuang-Yi
Lee, Chia-Hao
Cheng, Yen-Ju
交大名義發表
應用化學系
National Chiao Tung University
Department of Applied Chemistry
關鍵字: acceptor strength;benzothiophene-fused acceptor;ladder-type structure;nonfullerene acceptor;organic photovoltaics
公開日期: 11-九月-2019
摘要: Benzene-based 1,1-dicyanomethylene-3-indanone (IC) derivatives have been widely utilized as the end-group to construct acceptor-donor-acceptor type nonfullerene acceptors (A-D-A type NFAs). The extension of the end-group conjugation of nonfullerene acceptors (NFAs) is a rational strategy to facilitate intermolecular stacking of the end-groups which are responsible for efficient electron transportation. A bicyclic benzothiophene-based end-group acceptor, 2-(3-oxo-2,3-dihydro-1H-benzo[b]cyclopenta[d]thiophen-1-ylidene)malononitrile, denoted as alpha-BC was designed and synthesized. The Knoevenagel condensation of the unsymmetrical 1,3-diketo-precursor with one equivalent of malononitrile selectively reacts with the keto group attached at the alpha-position of the thiophene unit, leading to the isomerically pure benzothiophene-fused alpha-BC. The well-defined alpha-BC with extended conjugation was condensed with three different ladder-type diformylated donors to form three new A-D-A NFAs named BDCPDT-BC, DTCC-BC, and ITBC, respectively. The corresponding IC-based BDCPDT-IC, DTCC-IC, and ITIC model compounds were also synthesized for comparison. The incorporation of the electron-rich benzothiophene unit in the end-group upshifts the lowest unoccupied molecular orbital energy levels of the NFAs, which beneficially enlarges the V-oc values. On the other hand, the benzothiophene unit in alpha-BC not also imparts an optical transition in the shorter wavelengths around 340-400 nm for a better light harvesting ability but also promotes the antiparallel pi-pi stacking of the end-groups for efficient electron transport. The organic photovoltaic cell devices using a PBDB-T polymer and BC-based NFAs all showed the improved V-oc and J(sc) values. The BDCPDT-BC- and DTCC-BC-based devices exhibited a power conversion efficiency (PCE) of 10.82 and 10.74%, respectively, which outperformed the corresponding BDCPDT-IC-, and DTCC-IC-based devices (9.33 and 9.25%). More importantly, the ITBC-based device delivered the highest PCE of 12.07% with a J(sc) of 19.90 mA/cm(2), a V-oc of 0.94 V, and an fill factor of 64.51%, representing a 14% improvement relative to the traditional ITIC-based device (10.05%).
URI: http://dx.doi.org/10.1021/acsami.9b08462
http://hdl.handle.net/11536/153086
ISSN: 1944-8244
DOI: 10.1021/acsami.9b08462
期刊: ACS APPLIED MATERIALS & INTERFACES
Volume: 11
Issue: 36
起始頁: 33179
結束頁: 33187
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