Proceedings of NFA-Based Organic Solar Cells: Materials, Morphology and Fundamentals (NFASC)
Publication date: 25th January 2021
Organic solar cells (OSCs) represent an emerging photovoltaic technology, which have attracted extensive research interest due to its appealing advantages over traditional inorganic solar cells such as lightweight and flexibility. High power conversion efficiencies (PCE) of ca. 12% were obtained for devices based on the blends of conjugated polymers with fullerene derivatives [1]. A significant progress in efficiency of organic solar cells has been made by employing non-fullerene acceptors (NFAs). The state-of-the-art non-fullerene OSCs show impressive PCEs over 18% [2] that can be ascribed with strong absorption of NFAs in visible and NIR ranges and reduced voltage losses in devices attributed to negligible offset between the bandgap of the donor/acceptor materials, while retaining efficient charge separation.
In this work, we report on design of novel (X-DADAD)n conjugated copolymer comprising thiazolo[5,4-d]thiazole (X), benzo[c][1,2,5]thiadiazole (A-acceptor moiety) and thiophene (D-donor moiety) units and its investigation as electron donor material in OSCs with IT-4F [3] acceptor (Fig. 1). The photovoltaic properties of novel polymer were investigated in inverted BHJ solar cells. Conjugated polymer P1 showed promising results in non-fullerene organic solar cells. In particular, P1/IT-4F-based devices demonstrated high charge carrier mobilities and suppressed trap-assisted recombination resulting in impressive short-circuit currents of 22 mA cm-2 and overall PCEs of 9%.
These results evidence that conjugated polymers based on thiazolothiazole are promising absorber materials for non-fullerene OSCs. Further optimization of device architecture is expected to lead to improved device efficiencies.
The reported study was supported by Russian President Science Foundation МК-1103.2020.3