Ternary polymer solar cells based on wide bandgap and narrow bandgap non-fullerene acceptors with an efficiency of 16.40 % and a low energy loss of 0.53 eV. (September 2021)

• Record Type: Journal Article
• Authors: Keshtov, M.L.; Kuklin, S.A.; Agrawal, Anupam; Dahiya, Hemraj; Chen, Fang-Chung; Sharma, Ganesh D.
• Is Part Of: Materials today energy. Volume 21(2021)
• Publication Date: 2021-09
• Subjects: Ternary polymer solar cells -- Power conversion efficiency -- Low energy loss -- Suppressed charge recombination; Energy development -- Periodicals; Energy industries -- Periodicals; Power resources -- Periodicals; Energy policy -- Periodicals; Energy development; Energy industries; Energy policy; Power resources; Electronic journals; Periodicals; 621.042
• DOI: 10.1016/j.mtener.2021.100843
• Languages: English
• ISSNs: 2468-6069

Abstract

Abstract: Polymer solar cells (PSCs) are based on a ternary bulk heterojunction (BHJ) active layer consisting of the conjugated polymer PTB7-Th as a donor and two non-fullerene acceptors, that is, a wide bandgap acceptor based on perylene-diimide (PDI) unit, TPhEPDI-4, and narrow bandgap A-D-A acceptor denoted as BThIND-Cl. The lowest unoccupied molecular orbital offset between donor and acceptor materials used for the binary PTB7-Th:BThIND-Cl BHJ is about 0.34 eV, so there is still scope to narrow this offset and further reduce the energy loss through the incorporation of a second acceptor in a ternary active layer of PSCs. Interestingly, when TPhEPDI-4 is used as the second acceptor, there is an increase in open-circuit voltage ( V OC ) for the PSCs based on the PTB7-Th:TPhEPDI-4:BThIND-Cl ternary system owing to the creation of a cascade LUMO energy level alignment by TPhEPDI-4. After adjusting the weight ratios in the PTB7-Th:TPhEPDI-4:BThIND-Cl ternary BHJ layer to 1: 0.2:1.0 and subsequent solvent vapor annealing, we have achieved a power conversion efficiency of 16.40% (an energy loss of 0.53 eV and a VOC of 0.97 V) which is higher than that for binary PTB7-Th:BThIND-Cl (1:1.2) (14.18% with energy loss and an VOC of 0.58 eV and 0.91 V). Graphical abstract: Image 1 Highlights: Binary and ternary polymer solar cells with TPhEPDI-4 and BThIND-Cl nonfullerene acceptors and donor PTB7-Th fabricated. The binary PTB7:BThIND-Cl based polymer solar cells showed efficiency of about 14.18 %. The optimized PTB7-T:TPhEPDI-4:BThIND-Cl polymer solar cells showed high efficiency of 16.40 % with energy loss of 0.53 eV. The high efficiency is associated with efficient charge transfer and energy transfer in the ternary active layer.