Donor-acceptor （D-A）-conjugated polymers P（BT-C1） and P（BT-C2）, with dithieno[2,3-b;7,6-b]carbazole （C1） or dithi- eno[3,2-b;6,7-b]carbazole （C2） as D-unit and benzothiadiazole （BT） as A-unit, were synthes...Donor-acceptor （D-A）-conjugated polymers P（BT-C1） and P（BT-C2）, with dithieno[2,3-b;7,6-b]carbazole （C1） or dithi- eno[3,2-b;6,7-b]carbazole （C2） as D-unit and benzothiadiazole （BT） as A-unit, were synthesized. The optical bandgaps of the polymers are similar （1.84 and 1.88 eV, respectively）. The structures of donor units noticeably influence the energy levels and backbone curvature of the polymers. P（BT-C1） shows a large backbone curvature; its highest occupied molecular orbital （HOMO） energy level is -5.18 eV, whereas P（BT-C2） displays a pseudo-straight backbone and has a HOMO energy level of -5.37 eV. The hole mobilities of the polymers without thermal annealing are 1.9×10^-3 and 2.7×10^-3 cm^2 V-1 s^-1 for P（BT-C1） and P（BT-C2）, respectively, as measured by organic thin-film transistors （OTFTs）. Polymer solar cells using P（BT-C1） and P（BT-C2） as the donor and phenyl-Cyl-butyric acid methyl ester （PCyLBM） as the acceptor were fabricated. Power conversion efficiencies （PCEs） of 4.9% and 5.0% were achieved for P（BT-C1） and P（BT-C2）, respectively. The devices based on P（BT-C2） exhibited a higher Voc due to the deeper HOMO level of the polymer, which led to a slightly higher PCE.展开更多
基金financially supported by the National Basic Research Program of China(2014CB643504)the National Natural Science Foundation of China(51273193)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB12010300)
文摘Donor-acceptor （D-A）-conjugated polymers P（BT-C1） and P（BT-C2）, with dithieno[2,3-b;7,6-b]carbazole （C1） or dithi- eno[3,2-b;6,7-b]carbazole （C2） as D-unit and benzothiadiazole （BT） as A-unit, were synthesized. The optical bandgaps of the polymers are similar （1.84 and 1.88 eV, respectively）. The structures of donor units noticeably influence the energy levels and backbone curvature of the polymers. P（BT-C1） shows a large backbone curvature; its highest occupied molecular orbital （HOMO） energy level is -5.18 eV, whereas P（BT-C2） displays a pseudo-straight backbone and has a HOMO energy level of -5.37 eV. The hole mobilities of the polymers without thermal annealing are 1.9×10^-3 and 2.7×10^-3 cm^2 V-1 s^-1 for P（BT-C1） and P（BT-C2）, respectively, as measured by organic thin-film transistors （OTFTs）. Polymer solar cells using P（BT-C1） and P（BT-C2） as the donor and phenyl-Cyl-butyric acid methyl ester （PCyLBM） as the acceptor were fabricated. Power conversion efficiencies （PCEs） of 4.9% and 5.0% were achieved for P（BT-C1） and P（BT-C2）, respectively. The devices based on P（BT-C2） exhibited a higher Voc due to the deeper HOMO level of the polymer, which led to a slightly higher PCE.
