Oligomeric semiconductors enable high efficiency open air processed organic solar cells by modulating pre-aggregation and crystallization kinetics

Hao Xia, Ying Zhang, Kuan Liu, Wanyuan Deng, Mengbing Zhu, Hua Tan, Patrick W.K. Fong, Heng Liu, Xinxin Xia, Miao Zhang, Top Archie Dela Peña, Ruijie Ma, Mingjie Li, Jiaying Wu, Yongwen Lang, Jiehao Fu, Wai Yeung Wong, Xinhui Lu, Weiguo Zhu, Gang Li

Research output: Journal article publicationJournal articleAcademic researchpeer-review

7 Citations (Scopus)


Although massive progress in power conversion efficiencies (PCEs) has been made on organic solar cells (OSCs), the challenge remains to scale up high-performance OSCs that are compatible with industrial production conditions, such as post-treatment-insensitive, non-halogenated solvent, large-area printing, processing under atmospheric environment. In this study, two A–D–A–D–A type oligomers, named 5BDDBDT-F and 5BDDBDT-Cl, were designed and synthesized to be incorporated into binary OSCs. Ex situ and in situ characterizations were performed to reveal the underlying working mechanisms. The two-phase transitions: liquid-to-liquid and liquid-to-solid can be synergistically tailored to promote the molecular arrangement of the binary blend. Benefiting from the enhanced crystallinity, the oligomer can act as a bridging linker to rehabilitate the interfacial defects to reduce the trap-assisted recombination losses and thus the non-radiative recombination losses. As a result, using non-halogenated solvent (o-xylene), the best-performing OSCs with PCEs of 18.32% with a VOC of 0.850 V, an FF of 79.15% were achieved based on the PM6:5BDDBDT-F:BTP-eC9 ternary OSCs, and 18.43% with a VOC of 0.854 V, an FF of 79.29% were obtained based on PM6:5BDDBDT-Cl:BTP-eC9 ternary OSCs without any post-processing. More importantly, it is noteworthy that the large-area (1 cm2) blade coated devices based on PM6:5BDDBDT-F:BTP-eC9 and PM6:5BDDBDT-Cl:BTP-eC9, processed using non-halogenated solvent in an open-air environment without thermal-annealing treatment, obtained high PCE values of 17.11% and 17.06%, respectively, which are among the highest PCE values of blade-coated OSCs in open air. This study demonstrated an efficient strategy of controlling crystallization kinetics to improve the material crystallinity, as an effective guideline for achieving high photovoltaic performance in printing ternary OSCs, pushing the OSCs towards future manufacturing.

Original languageEnglish
Pages (from-to)6078 - 6093
JournalEnergy and Environmental Science
Publication statusAccepted/In press - Oct 2023

ASJC Scopus subject areas

  • Environmental Chemistry
  • Renewable Energy, Sustainability and the Environment
  • Nuclear Energy and Engineering
  • Pollution


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