Alkyl Chain End Group Engineering of Small Molecule Acceptors for Non-Fullerene Organic Solar Cells

Journal Article · Fri Aug 31 00:00:00 EDT 2018 · ACS Applied Energy Materials

DOI:https://doi.org/10.1021/acsaem.8b00851· OSTI ID:1483636

Qu, Jianfei ^[1]; Mu, Zhao ^[1]; Lai, Hanjian ^[1]; Chen, Hui ^[1]; Liu, Tao ^[1]; Zhang, Shuai ^[1]; Chen, Wei ^[2]; He, Feng ^[1]

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1. Southern Univ. of Science and Technology, Shenzhen (People’s Republic of China)
2. Argonne National Lab. (ANL), Lemont, IL (United States); The Univ. of Chicago, Chicago, IL (United States)

Alkyl chain engineering is widely used to prepare high-performance donor materials. However, relatively few studies have been focused on the alkyl chain optimization of acceptor materials. Herein, a series of new A-D-A (acceptor-donor-acceptor) type small molecule acceptors (ITBTR-C2, ITBTR-C4, ITBTR-C6, and ITBTR-C8) with indacenodithieno[3,2-b]thiophene (IDTT) as the core, benzothiadiazole (BT) as the π bridge, and ethyl-, butyl-, hexyl-, and octyl-substituted 2-(1,1-dicyanomethylene) rhodanine as the end groups, respectively, are successfully synthesized to systematically investigate the alkyl substituent effects on the physical, chemical, and electronic properties of A-D-A type small molecule acceptors. All molecules exhibit a strong and broad absorption from 600 to 800 nm as well as similar HOMO and LUMO energy levels. ITBTR-C6 with hexyl substitution showed the highest electron mobility and better phase separation morphology after blending with a donor polymer (PBDB-T). Therefore, inverted bulk heterojunction organic solar cells based on ITBTR-C6:PBDB-T blends exhibit the highest power conversion efficiency (PCE) of 8.26% with an open-circuit voltage (V_OC) of 0.89 V, a high short-circuit current density (J_SC) of 15.80 mA/cm2, and a fill factor (FF) of 58.21%, while the PCEs of ITBTR-C2-, ITBTR-C4-, and ITBTR-C8-based devices are 7.04%, 7.43%, and 7.93%, respectively. After solvent vapor and thermal annealing, both the J_SC and FF values of the ITBTR-C6-based device further increased, leading to a PCE of 9.29%. Furthermore, the results demonstrate that the alkyl chain substitution of A-D-A type small molecule acceptors is critical, and an appropriate adjustment of the alkyl chains can effectively enhance device performance.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: National Natural Science Foundation of China; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1483636
• Journal Information: ACS Applied Energy Materials, Journal Name: ACS Applied Energy Materials Journal Issue: 9 Vol. 1; ISSN 2574-0962
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
alkyl chains
end groups
molecular packing
nonfullerene acceptors
organic solar cells