摘要
In this work, a new A-D-A type nonfuUerene small molecular acceptor SilDT-IC, with a fused-ring silaindacenodithiophene （SilDT） as D unit and 2-（3-oxo-2,3-dihydroinden-l-ylidene）malononitrile （INCN） as the end A unit, was design and synthesized. The SilDT-IC film shows absorption peak and edge at 695 and 733 nm, respectively. The HOMO and LUMO of SilDT-IC are of -5.47 and -3.78 eV, respectively. Compared with carbon-bridging, the Si-bridging can result in an upper-lying LUMO level of an acceptor, which is benefit to achieve a higher open-circuit voltage in polymer solar cells （PSCs）. Complementary absorption and suitable energy level alignment between SilDT-IC and wide bandgap polymer donor PBDB-T were found. For the PBDB-T：SilDT-IC based inverted PSCs, a D/A ratio of 1 ： 1 was optimal to achieve a power conversion efficiency （PCE） of 7.27%. With thermal annealing （TA） of the blend film, a higher PCE of 8.16% could be realized due to increasing of both short-circuit current density and fill factor. After the TA treatment, hole and electron mobilities were elevated to 3.42 × 10-4 and 1.02 × 10-4 cm2·V-1.s-1, respectively. The results suggest that the SilDT, a Si-bridged fused ring, is a valuable D unit to construct efficient nonfullerene acceptors for PSCs.
In this work, a new A-D-A type nonfuUerene small molecular acceptor SilDT-IC, with a fused-ring silaindacenodithiophene （SilDT） as D unit and 2-（3-oxo-2,3-dihydroinden-l-ylidene）malononitrile （INCN） as the end A unit, was design and synthesized. The SilDT-IC film shows absorption peak and edge at 695 and 733 nm, respectively. The HOMO and LUMO of SilDT-IC are of -5.47 and -3.78 eV, respectively. Compared with carbon-bridging, the Si-bridging can result in an upper-lying LUMO level of an acceptor, which is benefit to achieve a higher open-circuit voltage in polymer solar cells （PSCs）. Complementary absorption and suitable energy level alignment between SilDT-IC and wide bandgap polymer donor PBDB-T were found. For the PBDB-T：SilDT-IC based inverted PSCs, a D/A ratio of 1 ： 1 was optimal to achieve a power conversion efficiency （PCE） of 7.27%. With thermal annealing （TA） of the blend film, a higher PCE of 8.16% could be realized due to increasing of both short-circuit current density and fill factor. After the TA treatment, hole and electron mobilities were elevated to 3.42 × 10-4 and 1.02 × 10-4 cm2·V-1.s-1, respectively. The results suggest that the SilDT, a Si-bridged fused ring, is a valuable D unit to construct efficient nonfullerene acceptors for PSCs.
基金
This work is supported by the National Natural Science Foundation of China （Nos. U1401244, 21225418, 51521002, and 91633301）, the National Basic Research Program of China （973 program, No. 2014CB643505）, and GDUPS （2013）.
