Synthesis and Characterization of Novel Photoactive Materials for Polymer Solar Cells

Abstract

The most widely used configuration of polymer solar cells is the so called “bulk hetero-junction” device in which the active layer consists of a blend of an electron-donating materials, e.g., a p-type conjugated polymers, and an electron-accepting material such as [6,6]-phenyl C61-butyric acid methyl ester. Several factors are important in further improving the efficiency of a PSC. Among these, the development of an electron-donating polymer has with low band gap to efficiently absorb light in the visible area of the solar spectrum and structural manipulation of the acceptor component, to optimize the solar cell performance. Therefore, there is still plenty of room to tune the efficiencies of BHJ photovoltaic cells. The main topics of this work are the synthesis of novel donating polymers and electron acceptors like fullerenes and their application in BHJ PSCs. Firstly, poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-selenienyl-2,1,3-benzothiadiazole)] (PCDSeBT), in which diselenienylbenzothiadiazole (DSeBT) monomer alternately flanks with 2,7-carbazole unit is synthesized for a low band gap polymer to harvest more solar photons. Besides, the photovoltaic properties of PCDSeBT in typical BHJ devices with PCBM are investigated. This work has already been published in Macromolecules. Secondly, N-9′-Heptadecanyldithieno[2,3-b;7,6-b]carbazole-based polymers (PTCZTBT, PTCZTfBT, PTCZTffBT, PTCZTTT, PTCZTPT, PTCZTQ, PTCZTfQ, PTCZTffQ), respectively, comprising a S- and N-containing heteroarene are prepared for potential usage in efficient PSCs. In the last part, considering possible combined effects from the 56 pi-electron system by the bisadduct framework and the increased light absorption in the visible region by the additional chromophores, we report the synthesis and characterization of bis-PCBM dyad containing 4-nitro-alpha-cyanostilbene units for usage in efficient PSCs. This work has already been published in Tetrahedron.