New conjugated molecules with two and three dithienyldiketopyrrolopyrrole (DPP) moieties substituted at meta positions of benzene toward p- and n-type organic photovoltaic materials.
Two conjugated molecules, TADPP3 and TADPP2-TT, are reported, in which three and two dithienyldiketopyrrolopyrrole (DPP) moieties, respectively, are substituted at the meta positions of benzene. Based on cyclic voltammetry and absorption data, TADPP3 and TADPP2-TT possess similar HOMO and LUMO energies of about -5.2 and -3.4 eV, respectively. Thin films of TADPP3 and TADPP2-TT exhibit p-type semiconducting behavior with hole mobilities of 2.36×10(-3) and 3.76×10(-4)  cm(2)  V(-1)  s(-1) after thermal annealing. Molecules TADPP3 and TADPP2-TT were utilized as p-type photovoltaic materials to fabricate organic solar cells after blending with phenyl C71 butyric acid methyl ester (PC71BM) and phenyl C61 butyric acid methyl ester (PC61BM). The relatively low JSC and fill factor values can be attributed to poor film morphologies based on AFM and XRD studies. A solar cell with a thin film of TADPP3 with PC71BM in a weight ratio of 1:2 exhibits a high open-circuit voltage (VOC) of 0.99 V and a power conversion efficiency (PCE) of 2.47 %. Interestingly, TADPP3 can also be employed as an n-type photovoltaic material. The blended thin film of TADPP3 with P3HT in a weight ratio of 1:2 gave a high VOC of 1.11 V and a PCE of 1.08 % after thermal annealing.
Beijing National Laboratory for Molecular Sciences, Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (P.R. China), Fax: (+86) 10-62562693.
Chenmin
C
Yu
Chang
C
He
Yang
Y
Yang
Zhengxu
Z
Cai
Hewei
H
Luo
Wenqiang
W
Li
Qian
Q
Peng
Guanxin
G
Zhang
Zitong
Z
Liu
Deqing
D
Zhang
donor-acceptor systems; electrochemistry; fullerenes; organic solar cells