期刊
JOURNAL OF MATERIALS CHEMISTRY A
卷 8, 期 7, 页码 3676-3685出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c9ta13293g
关键词
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资金
- National Natural Science Foundation of China (NSFC) [91433202, 21773262, 21327805]
- Inner Mongolia Normal University
- NSFC/RGC Joint Research Scheme [N_CUHK418/17]
- RGC AoE scheme [AoE/P-02/12]
- Hong Kong Research Grants Council [16306117, 16304218, 16306319]
- Shenzhen Technology and Innovation Commission [JCYJ20170818113905024]
Effective ternary material systems are usually achieved using a donor/acceptor guest that is structurally similar to the donor/acceptor host to maintain the film-morphology of the host binary blend. In this study, we report an unprecedented ternary material system, PBDB-TF:PBDB-T-SF:Y6, in which PBDB-T-SF is selected as the donor polymer guest of the PBDB-TF:Y6 binary blend. The absorption spectra of both polymers are almost overlapped and their energy levels are similar. However, the side-chains between the host (PBDB-TF) and the guest (PBDB-T-SF) are oriented differently, which modulates the morphology of the polymer phases from nanoscale (10-20 nm) fine fibrils in the host binary blend to an interpenetrating mesoscale polymer-crowd (>100 nm) with reduced phase crystallinity in the ternary blend. As a result, the electrical properties of the active layer are greatly improved: the hole mobility increases more than the electron mobility, resulting in balanced hole and electron mobilities; the monomolecular and bimolecular recombinations are both reduced; the charge carrier extraction is faster and the trap-assisted recombination is reduced, resulting in a longer recombination lifetime of charge carriers (0.19 mu s vs. 0.15/0.11 mu s). All of these contribute to the concurrently increased device fill-factor and short-circuit current-density, and finally improved efficiency (16.4%). Solid-state F-19 magic angle spinning nuclear magnetic microscopy is conducted to probe interaction between the host and guest donor polymers. This study demonstrates that mesoscale morphology such as the polymer-crowd induced by differently oriented side chains of the host-guest polymers can be a morphological feature of active layer toward high-efficiency organic photovoltaic cells.
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