New two-dimensional thiophene-acceptor conjugated copolymers for field effect transistor and photovoltaic cell applications
Journal
Chemistry of Materials
Journal Volume
22
Journal Issue
10
Pages
3290-3299
Date Issued
2010
Author(s)
Abstract
We report the synthesis, properties, and optoelectronic device applications of two-dimensional (2D) like conjugated copolymers, P4TBT, P4TDTBT, P4TDTQ, and P4TDPP, consisting of 2′,5′′-bis(trimethystannyl)-5, 5′′′-di-(2-ethylhexyl)[2,3′;5′, 2′′;4′′,2′′′]quarterthiophene (4T) with the following four acceptors of 4,7-dibromo-2,1,3-benzothiodiazole (BT), 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTBT), 2,3-bis(4-(2-ethylhexyloxy) phenyl)-5,8-bis[5′-bromodithien-2-ylquinoxalines] (DTQ), and 3,6-bis(5-bromothiophen-2-yl)-2,5-bis(2-ethylhexyl)pyrrolo[3,4-c]pyrrole-1, 4-dione (DPP). The optical band gaps (eV) of the studied conjugated copolymers are in the order of P4TDPP (1.29) < P4TDTBT (1.60) < P4TDTQ (1.83) < P4TBT (1.88). The 2D-like conjugated copolymers exhibited high field effect (FET) hole mobilities in the range of 10-1-10-4 cm 2 V-1 s-1. On the other hand, the FET electron mobilities were observed for P4TDTBT and P4TDPP because of their relatively low-lying LUMO level suitable for electron injection. In particular, P4TDPP showed the ambipolar characteristics with the hole and electronic mobilities of 0.115 cm2 V-1 s-1 (on/off ratio: 2.49×104) and 3.08×10-3 cm2 V -1 s-1 (on/off ratio: 7.34×102), respectively, which was strongly related to its ordered intermolecular chain packing based on the DSC and XRD results. The power conversion efficiencies (PCE) of the prepared polymer/PC71BM (1:3) based photovoltaic cells were in the range 1.28-1.67% under the illumination of AM 1.5G (100 mW/cm 2). The PCE could be enhanced up to 2.43% of the P4TDPP/PC 71BM (1:2) based device because of the balanced hole/electron mobility. The above results indicate that these two-dimensional 4T-acceptor conjugated copolymers could enhance the charge-transport characteristics and are promising materials for organic optoelectronic devices. © 2010 American Chemical Society.
SDGs
Other Subjects
Ambipolar characteristics; Benzothiadiazoles; Benzothiodiazole; Chain packing; Charge transport; Conjugated copolymers; Electronic mobility; High field; On/off ratio; Organic optoelectronics; Power conversion efficiencies; Promising materials; Thienyl; XRD; Conversion efficiency; Copolymerization; Copolymers; Electron mobility; Electrooptical devices; Field effect transistors; MESFET devices; Optoelectronic devices; Photoelectrochemical cells; Photovoltaic cells; Plastic products; Synthesis (chemical); Thiophene; Two dimensional; Organic polymers
Type
journal article