Small-Molecule Vinazene Acceptors for Bulk Heterojunction Organic Photovoltaics

Abstract

This paper reports the synthesis and characterization of a new vinazene-based small molecule, 4,7-bis(2-(1-(2-ethylhexyl)-4,5-dicyanoimidazol-2-yl) vinyl)diketopyrrolopyrrole (EV-DPP). The known vinazene-based small molecule, 4,7-bis(2-(1-(2-ethylhexyl)-4,5-dicyanoimidazol-2-yl)vinyl)benzo[c][1,2,5]thiadizole (EV-BT), was also prepared for comparison. The benzothiadiazole unit in EV-BT was replaced with a DPP unit in EV-DPP because DPP units are strong absorbing chromospheres. The UV absorption maxima of EV-DPP film (λ _max = 386, 573 nm) were greatly red shifted compared to the maxima of EV-BT film (λ _max = 337, 444 nm). Our preliminary device work showed the possibility of the use of EV-DPP as an electron acceptor in OPVs. The P3HT: EV-DPP film showed a better power conversion efficiency of 0.02% compared to P3HT: EV-BT due to the preferable UV absorption characteristics of EV-DPP.

Keywords:

• organic photovoltaic cells
• solar cells
• vinazene
• Heck coupling
• OPV
• DPP

Acknowledgment

This research was supported by a grant from Green Smart Card Platform Technologies Based on 3D Printed Electronic Devices Project of MKE (Ministry of Knowledge Economy) and ISTK (Korea Research Council for Industrial Science and Technology) and the Fundamental R&D Program for Core Technology of Materials funded by MKE of Republic of Korea.