| 초록 |
Conjugated D-π-A copolymers, PBDT-TPD, PBDT-ttTPD, PBDTT-TPD, and PBDTT-ttTPD, based on a BDT donor unit and TPD acceptor unit were designed and synthesized with different π-bridges via Stille-coupling. The effects of the π bridges on the optical, electrochemical, and photovoltaic properties of the polymers were investigated, in addition to the film crystallinities and carrier mobilities. A PCE of 6.81% was achieved from the inverted single device fabricated using the PBDTT-ttTPD:PC71BM blend film with 3 vol% DIO. A tandem photovoltaic device comprising the inverted PBDTT-ttTPD cell and a PTB7-based cell as the bottom and top cell components, respectively, showed a maximum PCE of 9.35% with a Voc of 1.58 V, Jsc of 8.00 mA/cm2, and FF of 74% under AM 1.5 G illumination at 100 mW/cm2.The obtained PCE of the bottom cell and FF of the tandem cell are, to the best of our knowledge, the highest reported to date for a tandem OPV device. |
