Highly efficient organic photovoltaics with enhanced stability through the formation of doping-induced stable interfaces

• Published in: Proceedings of the National Academy of Sciences - PNAS 2020-03, Vol.117 (12), p.6391-6397
• Main Authors: Jiang, Zhi, Wang, Fanji, Fukuda, Kenjiro, Karki, Akchheta, Huang, Wenchao, Yu, Kilho, Yokota, Tomoyuki, Tajima, Keisuke, Nguyen, Thuc-Quyen, Someya, Takao
• Format: Article
• Language: English
• Subjects: Annealing; Doping; Efficiency; Electronics; Energy conversion efficiency; Fabrication; Interface stability; Interfaces; Mixtures; Morphology; Photovoltaic cells; Photovoltaics; Physical Sciences; Power management; Power sources; Relative humidity; Wearable technology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1919769117

Flexible organic photovoltaics (OPVs) are promising power sources for wearable electronics. However, it is challenging to simultaneously achieve high efficiency as well as good stability under various stresses. Herein, we demonstrate the fabrication of highly efficient (efficiency, 13.2%) and stable OPVs based on nonfullerene blends by a single-step postannealing treatment. The device performance decreases dramatically after annealing at 90 °C and is fully recovered after annealing at 150 °C. Glass-encapsulated annealed OPVs show good environmental stability with 4.8% loss in efficiency after 4,736 h and an estimated T 80 lifetime (80% of the initial power conversion efficiency) of over 20,750 h in the dark under ambient condition and T 80 lifetime of 1,050 h at 85 °C and 30% relative humidity. This environmental stability is enabled by the synergetic effect of the stable morphology of donor/acceptor blends and thermally stabilized interfaces due to doping. Furthermore, the high efficiency and good stability are almost 100% retained in ultraflexible OPVs and minimodules which are mechanically robust and have long-term operation capability and thus are promising for future self-powered and wearable electronics.