Solar Energy Materials and Solar Cells, Vol.93, No.1, 108-113, 2009
Synthesis and photovoltaic properties of a star-shaped molecule with triphenylamine as core and benzo[1,2,5]thiadiazol vinylene as arms
A solution-processable and star-shaped molecule 4-((E)-2-(benzo[1,2,5]thiadiazol-4-yl)vinyl)-N,N-bis(4-((E)-2-(benzo[1,2,5]thiadiazol-7-yl)vinyl)phenyl)benzenamine (TPA-BT) has been designed and synthesized by palladium-catalyzed Heck reaction for the application in organic solar cells (OSCs). The molecule possesses a D-A structure with a triphenylamine core (donor unit) linked with three benzo[1,2,5]thiadiazole (acceptor unit) arms through double bonds. TPA-BT film shows a strong absorption peak in the visible wavelength range from 400 to 560 nm, which could be ascribed to the charge transfer band of the D-A structure of the molecule. The bulk-heterojunction OSCs with the device structure of ITO/PEDOT:PSS/TPA-BT:PCBM/Ca/Al (or Ba/Al) were fabricated by spin-coating the blend solution of TPA-BT and PCBM (1:3, w/w), in which TPA-BT was used as donor and PCBM as acceptor materials. The devices show a high open circuit voltage of ca. 0.9V and a power conversion under the illumination of AM 1.5 100 mW/cm(2). The results indicate that TPA-BT is a efficiency of 0.61%, promising solution-processable organic photovoltaic material. (C) 2008 Elsevier B.V. All rights reserved.
Keywords:Star-shaped molecules;Organic photovoltaic materials;Conjugated organic molecules;Solution-processable;Organic solar cells