High-Performance Green Solvent Processed Ternary Blended All-Polymer Solar Cells Enabled by Complementary Absorption and Improved Morphology

Ternary all-polymer solar cells (all-PSCs) attract considerable research attention owing to the simplicity of the single-junction device architecture and the broad absorption range of the light-harvesting layer. However, the difficulty in controlling the morphology of ternary blended films makes it challenging to develop high-performance ternary all-PSCs. Herein, we report on the development of efficient ternary blended all-PSCs by incorporating the narrow-bandgap electron-donating polymer PNTB, which contains a naphtho[1,2-c:5,6-c]bis([1,2,5]thiadiazole) moiety, into blend films comprising the wide-bandgap electron-donating copolymer PBTA-BO and the electron-accepting copolymer N2200. The resulting ternary blended devices reached an impressively high power conversion efficiency of 10.09%, which obviously outperforms those obtained from binary blended counterparts. The improved photovoltaic performance is attributable to the combined effects of the extended absorption profile, a favorable film morphology, and more efficient charge transfer. Of particular interest is that these ternary blend films are processed using a non-halogenated solvent, 2-methyltetrahydrofuran, which is promising for practical applications. These findings lend credence to the ternary approach as a facile and promising strategy for achieving high-performance all-PSCs.