Photovoltaic Molecule Containing Bi-4-Hexyl-Thienylenevinylene(BHTV)as the Conjugated Pi-Bridge for Bulk-Heterojunction Organic Solar Cells.

Linear D-A-D molecule with bi-(4-hexylthiophen-2-yl)vinyl(BHTV)as the conjugated π bridge between triphenylamine(TPA)donor unit(D)and 2-(4H-pyran-4-ylidene)malononitrile(PM)acceptor unit(A), TPA-BHTV-PM, has been designed and synthesized. It is applied in solution-processed organic solar cells(OSCs)as the donor material. Bi-(4-hexylthiophen-2-yl)vinyl was a π bridge containing double 4-hexyl-thienylenevinylene units and introduced into the TPA-PM-containing D-A structured molecule aiming to extend the absorbance and improve the photovoltaic properties. Through the investigation of optical and electrochemical properties of the molecule, TPA-BHTV-PM exhibits broad absorption in visible region from 350 nm to 700 nm and lower highest occupied molecular orbit(HOMO)energy level, which are fundamentals as donor in organic solar cells. The OSC devices were fabricated by spin-coating the blend solution of the TPA-BHTV-PM and PC71BM. The OSC device displayed an open circuit voltage(VOC)of 0.76 V, a short circuit current density(JSC)of 6.97 mA/cm2 and a fill factor(FF)of 38.7% which leading a power conversion efficiency(PCE)of 2.10%, under the illumination of AM.1.5, 100 mW/cm2. [ABSTRACT FROM AUTHOR]