Overcoming the trade-off between V_oc and J_sc: Asymmetric chloro-substituted two-dimensional benzo[1,2-b:4,5-b']dithiophene-based polymer solar cells

Journal Article · 04 November 2018 · Dyes and Pigments

DOI: https://doi.org/10.1016/j.dyepig.2018.10.071 · OSTI ID:1493727

Chao, Pengjie ^[1]; Liu, Longzhu ^[2]; Qu, Jianfei ^[2]; He, Qiming ^[3]; Gan, Shenglong ^[4]; Meng, Hong ^[1]; Chen, Wei ^[5]; He, Feng ^[2]

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1. Peking University, Shenzhen (China)
2. Southern University of Science and Technology, Shenzhen (China)
3. The University of Chicago, IL (United States)
4. Argonne National Lab. (ANL), Lemont, IL (United States)
5. Argonne National Lab. (ANL), Lemont, IL (United States); The University of Chicago, IL (United States)

To achieve the high PCE and simultaneously overcome the trade-off between open circuit voltage (V_oc) and short-circuit current density (J(_sc), the reasonable design of the donor material is still a great challenge in nonfullerene polymer solar cells (PSCs). In this paper, a pair of asymmetric 2D BDT-based wide band gap polymers, named PBPTBz-1C1 and PRPTBz-2C1, respectively, were designed and synthesized through simultaneously introducing a chloro-substituted thiophene and another alkoxylphenyl groups as side chains onto the same BDT unit. As expected, the polymers PBPTBz-1C1 and PBPTBz-2C1 exhibit the deeper HOMO levels of - 5.32 and - 5.41 eV, respectively, compared with the HOMO value of - 5.27 eV for chlorine -free substituted polymer PBPTBz-OCI. Therefore, the PBPTBz-2Cl:IT-M based PSCs exhibited a higher V_oc of 0.99 V, with an enhanced J_sc of 14.92 mA cm^-2 and PCE of 7.18%. The V_oc, J_sc and PCE were simultaneously enhanced from PEPTBz-OCLIT-M to PBPTBz-1C1:IT-M, then to PBPTBz-2C1:1T-M based PSCs successively. These results demonstrate that the challenge of the trade-off between V_oc and J_sc could be overcome through the asymmetric strategy of the chlorosubstituted thiophene and alkylphenyl groups as different side chains onto the same BDT unit. Hence, considering the low cost of starting materials and convenient introduction of chlorine atoms, the asymmetric chlorination of the side chain of BDT unit would be the great potential for achieving the high-performance PSCs.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1493727
• Journal Information: Dyes and Pigments, Journal Name: Dyes and Pigments Journal Issue: C Vol. 162; ISSN 0143-7208
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English