Insights into Bulk‐Heterojunction Organic Solar Cells Processed from Green Solvent. Issue 8 (3rd June 2021)

• Record Type: Journal Article
• Authors: Du, Zhifang; Mainville, Mathieu; Vollbrecht, Joachim; Dixon, Alana L.; Schopp, Nora; Schrock, Max; Peng, Zhengxing; Huang, Jianfei; Chae, Sangmin; Ade, Harald; Leclerc, Mario; Reddy, G. N. Manjunatha; Nguyen, Thuc-Quyen
• Is Part Of: Solar RRL. Volume 5:Issue 8(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-03
• Subjects: green solvents -- impedance spectroscopy -- organic photovoltaics -- recombination dynamics -- solid-state NMR; Solar energy -- Periodicals; Photovoltaic power generation -- Periodicals; Solar energy -- Research -- Periodicals; Photovoltaic power generation -- Research -- Periodicals; Periodicals; 333.7923
• DOI: 10.1002/solr.202100213
• Languages: English
• ISSNs: 2367-198X

Abstract

Abstract : The environmental impact of solution processed organic solar cells (OSCs) can be mitigated by introducing so‐called green solvents during the fabrication processes. However, the effects of such green solvents on the molecular‐level structures and optoelectronic properties lack in‐depth characterization. Here, insights into the structure–processing–property correlation of a PPDT2FBT:PC61 BM bulk‐heterojunction (BHJ) system processed from a green solvent, ortho ‐xylene ( o ‐XY), is investigated in comparison with the same blend processed from a traditional halogenated solvent, chlorobenzene (CB). The BHJ blends are characterized with various techniques probing at difference length scales, and an increased donor:acceptor (D:A) interfacial area as well as well‐mixed features in the bulk morphologies of the active layer are observed for the o ‐XY processed BHJ blend. Furthermore, molecular‐level differences in the D–A intermolecular interactions at the BHJ interfaces in o ‐XY and CB cast films are elucidated by 2‐dimensional solid‐state nuclear magnetic resonance (ssNMR) measurements and analysis. These results are consistent with the device properties, suggesting that the green‐solvent‐processed devices have longer charge carrier lifetimes and faster charge carrier extraction. The optimized PPDT2FBT:PC61 BM devices processed from o ‐XY can achieve a noteworthy higher power conversion efficiency (PCE) owing to a higher short‐circuit current density and fill factor. Abstract : The processing–property–performance correlation of a PPDT2FBT:PC61 BM blend system processed from a green solvent, ortho ‐xylene, is investigated in comparison with a traditional halogenated solvent, chlorobenzene. Green‐solvent‐processing devices show noteworthy higher power conversion efficiencies owing to the increased interfacial areas, favored orientation of PC61 BM in the vicinity of the PPDT2FBT aromatic core, faster extraction of charge carries, and suppressed recombination losses.