| 초록 |
In the last decade, alternating copolymers composed of electron-donating and electron-accepting units have been developed to achieve highly efficient polymer solar cells. In many cases, electron-donating and electron-accepting building blocks are linked with bridge units, such as thiophene, bithiophene, and thienothiophene, for the purpose to improve planarity of polymer backbone, to absorb photons by dual-band-absorption, and to enhance solubility of the copolymer (in this case, the use of alkylated bridge molecule). However, the effects of bridge unit on the energy level of polymer and the solar cell performance are not well-understood yet. In this study, we synthesized thieno[3,4-d]thiazole based alternating copolymers with several different bridge. As expected, the bridge molecule having less electron-donating ability leads to deeper HOMO energy levels of polymer and thus higher VOC of solar cell device. |
