biostudies-literatureLiu YMinistry of Science and Technology of the People&apos;s Republic of ChinaNational Natural Science Foundation of China4867-4871https://www.ebi.ac.uk/biostudies/studies/S-EPMC9077748biostudies-literatureUnknown8(9)In this study, a new acceptor-donor-acceptor (A-D-A) small molecule, DI3TCz, with carbazole as the central unit and 1,3-indanedione as the end group, was designed and synthesized for application in organic solar cells. In contrast to the molecule DR3TCz with rhodanine as end groups, DI3TCz exhibited deep a LUMO energy level and a nearly unchanged HOMO energy level with a narrow optical band gap of 1.75 eV and red shifted absorption. Compared with DR3TCz, the DI3TCz device showed a PCE of 6.46% with a remaining high <i>V</i> _oc value of 0.97 V, improved <i>J</i> _sc of 10.40 mA cm^-1 and a notable FF of 0.65, which is the highest PCE value reported to data for carbazole-based small molecules OPVs.RSC advancesEfficient carbazole-based small-molecule organic solar cells with an improved fill factor.PMC9077748914331012014CB643502Liu YFeng HNi WZhang HChen YWan XSun YLi MfalseEfficient carbazole-based small-molecule organic solar cells with an improved fill factor.In this study, a new acceptor-donor-acceptor (A-D-A) small molecule, DI3TCz, with carbazole as the central unit and 1,3-indanedione as the end group, was designed and synthesized for application in organic solar cells. In contrast to the molecule DR3TCz with rhodanine as end groups, DI3TCz exhibited deep a LUMO energy level and a nearly unchanged HOMO energy level with a narrow optical band gap of 1.75 eV and red shifted absorption. Compared with DR3TCz, the DI3TCz device showed a PCE of 6.46% with a remaining high <i>V</i> _oc value of 0.97 V, improved <i>J</i> _sc of 10.40 mA cm^-1 and a notable FF of 0.65, which is the highest PCE value reported to data for carbazole-based small molecules OPVs.2018-01-01T00:00:00Z2018 Jan2025-05-18T12:06:45.537Z2025-04-19T07:24:52.828ZS-EPMC90777483553955210.1039/c7ra10387e