Core effect on indacenodithieno[3,2-b]thiophene dimer based small molecule acceptors for non-fullerene polymer solar cells

• Published in: Synthetic metals Vol. 278; p. 116812
• Main Authors: Zhang, Meiling, Hu, Yuhui, Xu, Xiaopeng, Yu, Liyang, Li, Ying, Peng, Qiang
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.08.2021; Elsevier BV
• Subjects: Chromophores; Circuits; Construction standards; Core effect; Crystallization; Diimide; Dimer structure; Dimerization; Dimers; Energy conversion efficiency; Energy levels; Fullerenes; Indacenodithieno[3,2-b]thiophene; Non-fullerene acceptors; Photovoltaic cells; Polymer solar cell; Polymers; Power conversion efficiency; Solar cells; Structural stability; Non-fullerene acceptors; Dimer structure; Core effect; Indacenodithieno[3,2-b]thiophene; Polymer solar cell; Power conversion efficiency
• ISSN: 0379-6779; 1879-3290
• DOI: 10.1016/j.synthmet.2021.116812

Dimerization is a widely adopted approach to construct electron accepting materials for polymer solar cells (PSCs). Fullerene dimers were extensively explored with improved structural stability and perylene-diimide (PDI) dimers prevented the formation of undesired large crystals. However, dimers of indacenodithieno[3,2-b]thiophene (IDTT) chromophores have yet not been reported despite the great success in non-fullerene small molecule acceptors (NF-SMAs) such as ITIC. In this work, we designed and synthesized three IDTT dimers with conjugated cores or not and explored the core effect of introducing flexible dithiophene or rigid thienothiophene as linkage group. All the three IDTT dimers were found to be poorly crystallized and functional PSCs devices containing each of these dimers were successfully fabricated paring with donor polymer PBDB-T. The introduction of electron donating linkages raise energy levels of the dimers hence increased the open circuit voltages. Thienothiophene was found to be a more suitable linkage unit than dithiophene but the highest power conversion efficiency of 6.01% was recorded in devices based on dimer dIDTT without the linkage units. This work demonstrated the possibility of using IDTT chromophore to construct dimer NF-SMAs and revealed insights of core effect on their photovoltaic performance. [Display omitted] •IDTT-based dimers with or without core were synthesized as NF-SMAs for PSCs.•Introduction of flexible or rigid linkages between the IDTT units were explored.•Highest PCE of 6.01% was achieved in PSC devices containing dIDTT without any core.