Indacenodithienothiophene-based A-D-D0.625pt′0.625pt-D-A-type small-molecule donors for all-small-molecule organic solar cells

Research on all-small-molecule organic solar cells (SM-OSCs) is growing due to the advantages of small-molecule donor materials. In this study, we synthesized and characterized two small-molecule donors of A-D-D & PRIME;-D-A type based on highly fused indacenodithiophene (IDTT), namely BDT-IDTT-ORH and BDT-C8IDTT-ORH. The different side chains of these two molecules, 4-hexylphenyl and n-octyl, led to different crystallinities in the film state. The two synthesized donors exhibited absorption in the long wavelength range of 400-700 nm due to effective & pi;-conjugation caused by their planar structures. Because their absorption bands are complementary to that of the Y6 non-fullerene acceptor, these molecules showed potential as small-molecule donors in donor:Y6 blend for SM-OSCs. In particular, the BDT-C8IDTT-ORH:Y6 blend exhibited the highest power conversion efficiency (PCE) of 6.33%. This higher PCE is due to a relatively higher JSC value for BDT-C8IDTT-ORH with linear n-octyl side chains, thanks to its tighter molecular packing compared to that of BDT-IDTT-ORH with 4-hexylphenyl side chains.

Automated summary

This study synthesized and characterized two small-molecule donors, BDT-IDTT-ORH and BDT-C8IDTT-ORH, based on highly fused indacenodithiophene (IDTT). The different side chains of these molecules led to different crystallinities in the film state. These two synthesized molecules showed absorption in the long wavelength range and demonstrated potential as small-molecule donors in donor:Y6 blend for SM-OSCs. The BDT-C8IDTT-ORH:Y6 blend exhibited the highest power conversion efficiency (PCE) of 6.33% due to its tighter molecular packing compared to the BDT-IDTT-ORH blend.