Highly efficient ternary polymer solar cells based on a novel double-cabled third component with the same molecular fragments of donor and acceptor moieties

The red-shifting absorption of non-fullerene acceptor materials is the most important reason for the increasing efficiency of polymer solar cells (PSCs). However, the low absorption of non-fullerene materials in the short-wave direction and the full width at half maximum (FWHM) of the absorption spectra for active layer materials are only around 100 nm, which limits the further improvement of power conversion efficiency (PCE). Herein, we report a novel double-cabled material ITLYBT with the same molecular fragments of donor and acceptor moieties. The absorption spectra of ITLYBT are the superimpose of the donor backbones and the acceptor pendants with nearly 200 nm blue-shift caused by the enhanced steric hindrance, which works as an ideal third component for highly efficient ternary PSCs to broaden and complement the absorption spectra of the photoactive layer. By introducing ITLYBT into PBDB-T-2F:ITIC-4F blend, the ternary device shows enhanced J_sc and V_oc, and the over PCE increases from 12.50% to 13.14% due to the optimized phased separation and reduced charge recombination. These results indicate that double-cabled molecule is an ideal third component for construction high performance ternary PSCs.