Efficient Ternary Polymer solar cells based ternary active layer consisting of conjugated polymers and non-fullerene acceptors with power conversion efficiency approaching near to 15.5

• Published in: Solar energy 2021-03, Vol.216, p.217-224
• Main Authors: Sharma, Ganesh D., Suthar, Rakesh, Pestrikova, A.A., Nikolaev, A.Y., Chen, F.C., Keshtov, M.L.
• Format: Article
• Language: English
• Subjects: Absorption; Absorption spectra; Charge transport; Circuits; Complementary absorption spectra; Construction standards; Efficiency; Energy conversion efficiency; Energy levels; Energy transfer; Fast charge extraction; Fullerenes; Molecular orbitals; Open circuit voltage; Optimization; Photovoltaic cells; Polymers; Power conversion efficiency; Recombination; Short circuit currents; Short-circuit current; Solar cells; Solar energy; Solar power; Solvent vapor annealing; Suppressed recombination; Ternary polymer solar cells; Weight
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2021.01.027

[Display omitted] •Ternary active layer showed broad absorption profile ranging from 350 to 950 nm.•Optimized Ternary polymer solar cells showed higher PCE of 15.46%.•The energy transfer from P2 to PTB7-Th occurred in the ternary active layer.•In ternary polymer solar cells, fast charge extraction is occurred. Ternary polymer solar cells employing two polymers (P2, PTB7-Th) and one non-fullerene small molecule acceptor (Y6) were constructed using a conventional structure. The PTB7-Th, P2 and Y6 exhibit complementary absorption spectra therefore, the ternary blend consists of these three can maximize the photon harvesting efficiency which is advantageous to boost of short circuit current density of polymer solar cell. After the optimization of the weight ratios between the two donors and keeping constant the weight concentration of acceptor and following solvent vapor annealing in THF for 40 s, P2:PTB7-Th: Y6 (0.3:0.7:1.5) based polymer solar cells attained the power conversion efficiency of 15.46%, superior to that for polymer solar cells based on binary active layers i.e., P2:Y6 (12.62%) and PTB7-Th:Y6 (12.84%), respectively. The open-circuit voltage for the P2:PTB7-Th:Y6 is about 0.88 V which is in between the values for P2:Y6 (0.94 V) and PTB7-Th:Y6 (0.85 V), consistent with the different highest occupied molecular orbital energy level for P2 (−5.38 eV) and PTB7-Th (−5.27 eV). The enhancement in the short circuit current may be associated with the broader absorption profile of the ternary active layer relative to binary counterparts while the enhanced value of fill factor may be originated from the balanced charge transport, suppressed recombination, and faster charge extraction.