Study On Near Infrared Sensitizers With Lateral Anchor Group For Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSC) have attracted considerable interests due to relatively high solar energy conversion efficiency and low cost. Photosensitizer which absorbs the sunlight and then injects electrons into the conduction band of the oxide is one of the most important parts of DSC to get higher efficiency and longer used life.In the design and synthesis of dyes, Donor-Ï€Spacer-Acceptor (D-Ï€-A) organic dyes are known for their excellent high extinction molar absorption coefficients, easily designing and optimizing of molecular structures, making them attractive for DSC. However, two problems remain challenging:new chromophores for sensitization in the near infrared region (NIR), and new anchoring groups non-coupled to the acceptor parts of the dye molecules.6 kinds of novel NIR D-Ï€-A organic dyes were designed and synthesized, with substituted tetrahydroquinoline as the electron donor, lateral chain carboxylic acid as the anchoring group, several cyano groups as the electron acceptors and substituted and unsubsitituted thienyl as electron spacers (thienyl, hexylthienylvinyl, and 3, 4-ethylenedioxythiophene (EDOT)). Comparing with traditional D-Ï€-A dyes for DSC (using cyanoacrylic acid as acceptor and the anchoring group), the anchoring group in these dyes was separated from the acceptor units. It is easy to well tune the HOMO-LUMO levels by modifying the substituents of both doner moiety and acceptor moiety of the dyes. The photophysical and electrochemical properties of these dyes were studied and DSC were fabricated. The relationship between dyes'structures and solar cell performances has been investigated.The introductions of long carbon chain into donor part can suppress electron's aggregation on the surface of TiO2 and increase electron lifetime in TiO2 films, inhibit dark current thus increase the opencircut-voltages, the absorption of dyes can even red shifted to 1000 nm.