To Fluorinate or Not to Fluorinate in Organic Solar Cells: Achieving a Higher PCE of 15.2% when the Donor Polymer is Halogen‐Free. Issue 47 (6th November 2021)

• Record Type: Journal Article
• Authors: Wu, Jianglin; Liao, Chuang‐Yi; Chen, Yao; Jacobberger, Robert M.; Huang, Wei; Zheng, Ding; Tsai, Kuen‐Wei; Li, Wei‐Long; Lu, Zhiyun; Huang, Yan; Wasielewski, Michael R.; Chang, Yi‐Ming; Marks, Tobin J.; Facchetti, Antonio
• Is Part Of: Advanced energy materials. Volume 11:Issue 47(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-11-06
• Subjects: blend morphology -- bulk heterojunction blend -- fluorination effects -- organic solar cells -- thieno[3, 4‐c]pyrrole‐4, 6‐dione; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.202102648
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: Fluorination of the donor and/or acceptor blocks of photoactive semiconducting polymers is a leading strategy to enhance organic solar cell (OSC) performance. Here, the effects are investigated in OSCs using fluorine‐free (TPD‐3 ) and fluorinated (TPD‐3F ) donor polymers, paired with the nonfullerene acceptor Y6. Interestingly and unexpectedly, fluorination negatively affects performance, and fluorine‐free TPD‐3 :Y6 OSCs exhibit a far higher power conversion efficiency (PCE = 14.5%) than in the fluorine‐containing TPD‐3F :Y6 blends (PCE = 11.5%). Transmission electron microscopy (TEM) analysis indicates that the TPD‐3F :Y6 blends have larger phase domain sizes than TPD‐3 :Y6, which reduces exciton dissociation efficiency to 81% for TPD‐3F :Y6 versus 93% for TPD‐3 :Y6. Additionally, grazing incidence wide‐angle X‐ray scattering (GIWAXS) reveals that the TPD‐3F :Y6 blends are less textured than those of TPD‐3 :Y6, while space‐charge limited currents reveal lower and unbalanced hole/electron mobility in TPD‐3F :Y6 versus TPD‐3 :Y6 blends. Charge recombination dynamic, transient absorption, and donor–acceptor miscibility assays additionally support this picture. Furthermore, conventional architecture TPD‐3 :Y6 OSCs deliver a PCE of 15.2%, among the highest to date for halogen‐free polymer donor OSCs. Finally, a large‐area (20.4 cm 2 ) TPD‐3 :Y6 blend module exhibits an outstanding PCE of 9.31%, one of the highest to date for modules of area >20 cm 2 . Abstract : A high power conversion efficiency (PCE) of 15.2% is achieved by via a halogen‐free, polymer donor in TPD‐3 :Y6‐based organic solar cells, which is far higher than that of its fluorined counterpart, TPD‐3F (11.4%). Comparative characterization including, transmission electron microscopy, grazing incidence wide‐angle X‐ray scattering, transient absorption, miscibility, measurements explain this result. Additionally, a PCE of 9.31% is achieved by TPD‐3 :Y6‐based 20.4 cm 2 modules.