Pyrrolo[3,4-g]quinoxaline-6,8-dione-based conjugated copolymers for bulk heterojunction solar cells with high photovoltages
| Autor: | Mats Fahlman, Eva Olsson, Olof Bäcke, Ergang Wang, Mats Andersson, Kim Bini, Chuanfei Wang, David I. James, Xiaofeng Xu |
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| Přispěvatelé: | Xu, Xiaofeng, Wang, Chuanfei, Backe, Olof, James, David I, Bini, Kim, Olsson, Eva, Andersson, Mats, Fahlman, Mats, Wang, Ergang |
| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
Materials science
Polymers and Plastics business.industry Organic Chemistry Bioengineering Polymer Chemistry 7. Clean energy Biochemistry Polymer solar cell Crystallography chemistry.chemical_compound Quinoxaline chemistry Bathochromic shift Side chain Copolymer Optoelectronics Moiety business Imide HOMO/LUMO |
| Zdroj: | Polymer Chemistry (1759-9954) vol.6(2015) |
| Popis: | A new electron-deficient building block 5,9-di(thiophen-2-yl)-6H-pyrrolo[3,4-g]quinoxaline-6,8(7H)-dione (PQD) was synthesized via functionalizing the 6- and 7-positions of quinoxaline (Qx) with a dicarboxylic imide moiety. Side chain substitution on the PQD unit leads to good solubility which enables very high molecular weight copolymers to be attained. The fusion of two strong electron-withdrawing groups (Qx and dicarboxylic imide) makes the PQD unit a stronger electron-deficient moiety than if the unit had just one electron-withdrawing group, thus enhancing the intramolecular charge transfer between electron-rich and deficient units of the copolymer. Four PQD-based polymers were synthesized which feature deep-lying highest occupied molecular orbital (HOMO) levels and bathochromic absorption spectra when compared to PBDT-Qx and PBDT-TPD analogues. The copolymers incorporated with benzo[1,2-b:4,5-b']dithiophene (BDT) units show that the 1D and 2D structural variations of the side groups on the BDT unit are correlated with the device performance. As a result, the corresponding solar cells (ITO/PEDOT:PSS/polymer: PC71BM/LiF/Al) based on the four copolymers feature very high open-circuit voltages (V-oc) of around 1.0 V. The copolymer PBDT-PQD1 attains the best power conversion efficiency of 4.9%, owing to its relatively high absorption intensity and suitable film morphology. The structure-property correlation demonstrates that the new PQD unit is a promising electron-deficient building block for efficient photovoltaic materials with high V-oc. |
| Databáze: | OpenAIRE |
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