| 초록 |
To investigate the effect of combination between strong electron donor and strong electron acceptor on the diverse properties of conjugated small molecules based on carbazole (Cz) having 2,7-linkage as an electron donor and 2,1,3-benzothiadiazole (BT), 2,7-bis-[5-(7-methyl-benzo[1,2,5]thiadiazol-4-yl)-thiophen-2-yl]-9-(2-octyl-dodecyl)-9H-carbazole (Cz-BT) and 2,7-bis-[5'-(7-methyl-benzo[1,2,5]thiadiazol-4-yl)-[2,2']bithiophenyl-5-yl]-9-(2-octyl-dodecyl)-9H-carbazole (CzT-BT), are synthesized by the Suzuki coupling reaction. In addition, we introduce thiophene (T) ring as a -bridge to extend the effective conjugation length. Cz-BT and CzT-BT exhibit the band gap of 2.15 and 2.26 eV, respectively, due to intermolecular charge transfer between Cz and BT. As increasing the number of T rings lowers the band gap and leads to an elevation of the HOMO and LUMO energy levels. Maximum power conversion efficiency (PCE) of the OSCs based on small molecules is showed up to 1.58%. |
