Impact of Nonfullerene Molecular Architecture on Charge Generation, Transport, and Morphology in PTB7‐Th‐Based Organic Solar Cells
[1]
- Department of Materials Science and Engineering North Carolina State University Raleigh NC 27695 USA
- Department of Chemistry and Physics Fayetteville State University Fayetteville NC 28301 USA
- Department of Materials Science and Engineering City University of Hong Kong Hong Kong SAR P. R. China, City University of Hong Kong Shenzhen Research Institute Shenzhen P. R. China
- Department of Physics Organic and Carbon Electronics Lab (ORaCEL) North Carolina State University Raleigh NC 27695 USA
- School of Chemistry and Biochemistry Center for Organic Photonics and Electronics Georgia Tech Polymer Network Georgia Institute of Technology Atlanta GA 30332 USA
Abstract Despite the rapid development of nonfullerene acceptors (NFAs), the fundamental understanding on the relationship between NFA molecular architecture, morphology, and device performance is still lacking. Herein, poly[[4,8‐bis[5‐(2‐ethylhexyl)thiophene‐2‐yl]benzo[1,2‐b:4,5‐b0]dithiophene‐2,6‐diyl][3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]‐thieno[3,4‐b]thiophenediyl]] (PTB7‐Th) is used as the donor polymer to compare an NFA with a 3D architecture (SF‐PDI4) to a well‐studied NFA with a linear acceptor–donor–acceptor (A–D–A) architecture (ITIC). The data suggest that the NFA ITIC with a linear molecular structure shows a better device performance due to an increase in short‐circuit current ( J sc ) and fill factor (FF) compared to the 3D SF‐PDI4. The charge generation dynamics measured by femtosecond transient absorption spectroscopy (TAS) reveals that the exciton dissociation process in the PTB7‐Th:ITIC films is highly efficient. In addition, the PTB7‐Th:ITIC blend shows a higher electron mobility and lower energetic disorder compared to the PTB7‐Th:SF‐PDI4 blend, leading to higher values of J sc and FF. The compositional sensitive resonant soft X‐ray scattering (R‐SoXS) results indicate that ITIC molecules form more pure domains with reduced domain spacing, resulting in more efficient charge transport compared with the SF‐PDI4 blend. It is proposed that both the molecular structure and the corresponding morphology of ITIC play a vital role for the good solar cell device performance.
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- DE‐AC02‐05CH11231
- OSTI ID:
- 1456280
- Journal Information:
- Advanced Functional Materials, Journal Name: Advanced Functional Materials Vol. 28 Journal Issue: 32; ISSN 1616-301X
- Publisher:
- Wiley Blackwell (John Wiley & Sons)Copyright Statement
- Country of Publication:
- Germany
- Language:
- English
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