PTPD[2F]T shows rigidplanar backbone and well delocalized frontier orbitals. OSCsbased on PTPD[2F]T achieved PCEs up to 4.4% when usingPTB7–Th as the polymer donor. Very recently, a third electrondeficient motif, 2,1,3-benzothiadiazole (BT) was introduced intothe all- thiophene-based polymer acceptor [103]. The newlydeveloped polymer acceptor P2TPDBT[2F]T (P26) (Fig. 7) exhibited narrower bandgap and highly improved electron mobility.All-polymer solar cells based on P2TPDBT[2F]T and polymerdonor PBDT-TS1 achieved a notable PCE of 4.8%. Although thephotovoltaic performance of these polymer acceptors still laggedbehind fullerene derivatives and PDI/NDI-based polymer acceptors, these novel designs broadened the diversity of polymeracceptors with tunable electronic and optical properties(Table 1).