Efficient polymer solar cells that use conjugated polyelectrolyte with a tetravalent amine-end side chain

Abstract Conjugated polyelectrolyte based on benzotriazole (BT) with tetravalent amine-end side chain and benzothiadiazole (BTz) conjugated alternating repeat units, named PBTBTz-TMAI was initially designed and synthesized. Fullerene- and non-fullerene-based polymer solar cells were fabricated using PBTBTz-TMAI as the cathode interlayer. Consequently, power conversion efficiencies of 8.4% and 10.5% were achieved for the fullerene PTB7:PC71BM-based and non-fullerene PBDB-T:ITIC-based single-junction devices, respectively. The enhanced performance is attributed to the appropriate energy level alignment of the active layer with PBTBTz-TMAI and the efficient electron transfer from the active layer to the cathode electrode.