Fused polycyclic lactam-based π-conjugated polymers for efficient nonfullerene organic solar cells

Abstract

The development of high-performance wide-bandgap polymers has attracted significant attention in recent non-fullerene organic solar cells (NF-OSCs) research, as the expansion of the options of polymer donors that are appropriately matched with nonfullerene acceptors can lead to the further improvement of photovoltaic properties. In this study, two wide-bandgap π-conjugated polymers, namely, P(TPTI-BDT) and P(2DTP-BDT), based on fused pentacyclic bis-lactam and dimeric bis-lactam units, were prepared and used as the donor materials for NF-OSCs with IT-4F as the acceptor. The NF-OSCs based on the P(TPTI-BDT):IT-4F blends outperformed the corresponding P(2DTP-BDT):IT-4F-based devices, achieving high power conversion efficiencies of up to 11.7% without processing additives or post-treatments. Further investigation of the thin-film morphologies using X-ray diffraction and transmission electron microscopy revealed that both P(TPTI-BDT) and P(2DTP-BDT) adopted preferential face-on molecular orientations and formed finely nano-segregated bulk-heterojunction morphologies when blended with IT-4F.