Synthesis and photovoltaic properties of a solution-processable organic molecule containing triphenylamine and DCM moieties

A solution processible organic conjugated molecule 2-[2,6-bis-(2-{4-[2-(4-diphenylaminophenyl)vinyl]phenyl}vinyl)pyran-4-ylidene]malononitrile (TPA-DCM-TPA) was designed and synthesized for application in organic solar cells (OSCs). The molecule consists of two electron-rich triphenylamine moieties and one electron-deficient 2-pyran-4-ylidenemalononitrile unit linked with conjugated bridges. The optical and electrochemical properties, the light-induced electron spin resonance (LESR), and the electronic ground state configuration of the compound were characterized. TPA-DCM-TPA film showed a broad absorption band covering from 350 to 650 nm. The bulk-heterojunction OSCs with the device structure of ITO/PEDOT:PSS/TPA-DCM-TPA:PCBM/LiF/Al or Ba/Al were fabricated, in which TPA-DCM-TPA was used as donor and PCBM as acceptor material. The open-circuit voltage, short-circuit current, and power-conversion efficiency of the optimized OSC with Ba/Al as cathode, TPA-DCM-TPA:PCBM = 1:3 (w/w), and ca. 85 nm thickness of the active layer reached 0.9 V, 2.14 mA/cm(2), and 0.79%, respectively, under the illumination of AM1.5, 100 mW/cm(2). The results indicate that TPA-DCM-TPA is a promising photovoltaic organic molecule.