Cost-Efficiency balanced polymer acceptors based on lowly fused Dithienopyrrolo[3, 2b]benzothiadiazole for 16.04% efficiency All-Polymer solar cells.

BTP-based polymer accepters with low-lying HOMO level and reduced synthesis complexity were developed for all polymer solar cells. Top PCEs of 14.32% and 16.04% were achieved in binary and ternary blends using such BTP-based polymer acceptors, even featuring a very low FOM of 3.65. [Display omitted] • BTP based polymer acceptors were designed and synthesized. • The BTP-based polymers show high performances with the lowest cost-efficiency. • The top PCE of 16.04% was obtained in ternary blend All-PSCs. All-polymer solar cells (All-PSCs) attracted increasing attention due to the outstanding thermal stability and mechanical properties. The current prevailing polymer acceptors for most efficient All-PSCs are polymerized high-performance small molecule acceptor of Y6, i.e. the dithienothiopheno[3,2-b]-pyrrolobenzothiadiazole (BTTP) based polymers. However, the BTTP-based polymers often show relatively shallow highest occupied molecular orbital (HOMO) energy level and high figure of merit (FOM), which limit the rational selection of paring donor polymers. Herein, we presented two low-cost polymer acceptors, namely as BTP-T2F and BTP-2T2F, based on lowly fused dithienopyrrolo[3,2b]benzothiadiazole (BTP, removing two thiophene cycles from BTTP). The BTP-based polymers exhibited deeper HOMO levels around −5.90 eV, which could match variable donor polymers with low-lying HOMO levels, such as low-cost PTQ10. Additionally, the synthesis was significantly simplified compared to BTTP-based polymers. A power conversion efficiency (PCE) of 14.32% was achieved in binary blend device containing PTQ10:BTP-2T2F. By adding a miscibility-enhancing PBDTCl-TPD as a third component, the top PCE of 16.04% was obtained in ternary blend All-PSCs. Combining the high device performance and low estimated cost, extraordinary cost-efficiency balance was realized within these BTP-based polymer acceptors. [ABSTRACT FROM AUTHOR]