| 초록 |
A novel copolymer, PNDT-BTN, based on naphtho[2,1-b:3,4-b']dithiophene (NDT) and alkoxy naphthalene was designed and synthesized by Pd-catalyzed Stille-coupling method. The copolymer showed good solubility and film-forming ability combining with good thermal stability. PNDT-BTN exhibited a broad absorption from 300 to 600 nm with an absorption peak centered at 492 nm. The HOMO and LUMO energy levels of the polymer were estimated to be -5.56 eV and -3.48 eV, respectively. The polymer solar cell fabricated from the blend of the polymer as donor and PC71BM as acceptor exhibited a high power conversion efficiency of 4.29% with a high VOC of 0.98 V. To the best of our knowledge, this is among the highest VOC values for PSCs based on NDT derivatives. This work demonstrate that the replacement of vinylene group in conjugated polymer with alkoxy naphthalene moieties is able to significantly lower the HOMO energy levels, and therefore, increase the open circuit voltage of solar cells. |
