Structure-Property Relationships for the Electronic Applications of Bis-Adduct Isomers of Phenyl-C 61 Butyric Acid Methyl Ester.

Autor: Hou X; Department of Physics, Imperial College London, London SW7 2AZ, U.K.; School of Physical and Chemical Sciences, Queen Mary University of London, London E1 4NS, U.K., Coker JF; Department of Physics, Imperial College London, London SW7 2AZ, U.K., Yan J; Department of Physics, Imperial College London, London SW7 2AZ, U.K.; School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong Province 518172, P. R. China., Shi X; Department of Physics, Imperial College London, London SW7 2AZ, U.K., Azzouzi M; Department of Physics, Imperial College London, London SW7 2AZ, U.K., Eisner FD; Department of Physics, Imperial College London, London SW7 2AZ, U.K., McGettrick JD; SPECIFIC, Swansea University Bay Campus, Swansea, Wales SA1 8EN, U.K., Tuladhar SM; Department of Physics, Imperial College London, London SW7 2AZ, U.K., Abrahams I; School of Physical and Chemical Sciences, Queen Mary University of London, London E1 4NS, U.K., Frost JM; Department of Physics, Imperial College London, London SW7 2AZ, U.K., Li Z; School of Engineering and Materials Sciences, Queen Mary University of London, London E1 4NS, U.K., Dennis TJS; Department of Chemistry, Xi'an Jiaotong-Liverpool University, Suzhou 215123, China., Nelson J; Department of Physics, Imperial College London, London SW7 2AZ, U.K.
Jazyk: angličtina
Zdroj: Chemistry of materials : a publication of the American Chemical Society [Chem Mater] 2023 Dec 28; Vol. 36 (1), pp. 425-438. Date of Electronic Publication: 2023 Dec 28 (Print Publication: 2024).
DOI: 10.1021/acs.chemmater.3c02353
Abstrakt: Higher adducts of a fullerene, such as the bis-adduct of PCBM (bis-PCBM), can be used to achieve shallower molecular orbital energy levels than, for example, PCBM or C 60. Substituting the bis-adduct for the parent fullerene is useful to increase the open-circuit voltage of organic solar cells or achieve better energy alignment as electron transport layers in, for example, perovskite solar cells. However, bis-PCBM is usually synthesized as a mixture of structural isomers, which can lead to both energetic and morphological disorder, negatively affecting device performance. Here, we present a comprehensive study on the molecular properties of 19 pure bis-isomers of PCBM using a variety of characterization methods, including ultraviolet photoelectron spectroscopy, thermal gravimetric analysis, differential scanning calorimetry, single crystal structure, and (time-dependent) density functional theory calculation. We find that the lowest unoccupied molecular orbital of such bis-isomers can be tuned to be up to 170 meV shallower than PCBM and up to 100 meV shallower than the mixture of unseparated isomers. The isolated bis-isomers also show an electron mobility in organic field-effect transistors of up to 4.5 × 10 -2 cm 2 /(V s), which is an order of magnitude higher than that of the mixture of bis-isomers. These properties enable the fabrication of the highest performing bis-PCBM organic solar cell to date, with the best device showing a power conversion efficiency of 7.2%. Interestingly, we find that the crystallinity of bis-isomers correlates negatively with electron mobility and organic solar cell device performance, which we relate to their molecular symmetry, with a lower symmetry leading to more amorphous bis-isomers, less energetic disorder, and higher dimensional electron transport. This work demonstrates the potential of side chain engineering for optimizing the performance of fullerene-based organic electronic devices.
Competing Interests: The authors declare no competing financial interest.
(© 2023 The Authors. Published by American Chemical Society.)
Databáze: MEDLINE
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