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Polymer Additive SBS: More Sensitive to Fluorinated Asymmetric‐Indenothiophene‐Based Polymer Solar Cells
Author(s) -
Jiang Chenglin,
Li Huan,
Yang Shijian,
Li Xiaoyu,
Wang Haiqiao
Publication year - 2021
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.202004771
Subject(s) - materials science , polymer , copolymer , crystallization , polymer solar cell , chemical engineering , solvent , energy conversion efficiency , polymer chemistry , organic chemistry , composite material , optoelectronics , chemistry , engineering
Abstract Polymer solar cells (PSCs) typically suffer from a negative effect of the residual solvent on the performance due to the use of the solvent processing additive. One solution to solve this problem is to use a solid polymer additive that can promote the phase separation of the blend film of the active layers. In this work, two new D−A type photovoltaic polymers, namely PIT‐DTBT and PIT‐DTffBT, based on asymmetric indenothiophene (IT) donor unit and nonfluorinated or difluorinated benzothiadiazole acceptor unit were designed and synthesized, respectively. Then a triblock copolymer, poly(styrene‐ block ‐butadiene‐ block ‐styrene) (SBS), was employed as a polymer additive into the active layers of PIT‐DTBT/PC 71 BM and PIT‐DTffBT/PC 71 BM based devices, and the SBS effect on the morphology of the blend films of the active layers, and then the performance of the two kinds of devices was investigated. The results demonstrated that the addition of SBS improved the molecule packing and induced the crystallization of PIT‐DTffBT, making the device have higher charge mobilities, more efficient charge dissociation and collection, and less charge recombination. Thus, power conversion efficiency (PCE) was increased from 4.61 % to 6.57 % for PIT‐DTffBT based device. Although almost no improvement in molecule packing and crystallization was observed for SBS‐treated nonfluorinated PIT‐DTBT, the fact of PCE of the PIT‐DTBT based device increased from 2.94 % to 3.13 % can also be attributed to the improved phase separation of the blend film by SBS. These findings indicate that SBS is more sensitive to fluorinated polymers than nonfluorinated polymers in improving molecule packing and inducing crystallization.