Synthesis And Photovoltaic Properties Research Of Triphenyl Amine Dyes

The solar energy is abundant and infinite and it is one of the best ways to solve the energy crisis. In recent years, Dye-Sensitized Solar Cells have atracted much attention because of large-area fabrication, potentially low cost and ease of designing materials based on the molecular level.As the heart of the dye-sensitized solar cell (DSSC),Dye is the most important parts for DSSCs getting higher efficiency.In this thesis, we have designed and synthesized seven new dyes,which containing donor cascade of triarylamine and N,N-dimethylarylamine moieties. Both triarylamine and N,N-dimethylaryl amine constructed an electron donor cascade. These compounds not only have double electron-donating groups, but also can achieve the purpose of cascading electron-donating. Moreover, dimethylaryl amine has fan-shaped structure.This structure can avoid molecular aggregation, crystallization and improve the stability of the device. The structures of the dyes have been characterized by IR nuclear, magnetic resonance and mass spectra (MS) techology. The photophysical, electrochemical properties and the performance on Dye-sensitized nanocrystalline solar cells (DSSC) of the dyes are measured and studied.The compounds have strong absorption in the visible spectrum,especially in 400-500 nm. The dyes also give high molar extinction coefficient. It shows a good ability to capture light. Through the electrochemical properties test of dyes, both the ground state and excited state redox potential of ZL-1 7 conform the thermodynamic requirements of TiO₂ conduction band and regeneration. By test and research the DSSC of ZL-1 7, we find that change of dye structures has important effect on the Performance of DSSC. When the cyanoacetic acid replaced with rhodanine-3-acetic acid, the power conversion efficiency of the DSSC obviously drop.It may be attributed to the presence of the–CH2- group between the ring and–COOH. This resultes in the position of LUMO isolated from the -COOH anchoring group. Thus the ZL-5～7 dyes prevent electrons from effectively injecting into the TiO₂ conduction band via the carboxyl group and give lower efficiency. Additionally, the organic sensitizer introducingÏ€-electron systems between donor and acceptor moieties had better performance than the dyes development introducingÏ€-electron systems between two donors.The dyes ZL-5～7 have high maximum IPCE value. The maximal monochromatic incident photon-to-current conversion efficiency (IPCE) of ZL-4 can reach to 93%, with a short-circuit photocurrent density (Jsc) 10.8 mA cm^-2, an open-circuit photovoltage (Voc) 690 mV, and fill factor (FF) 0.61, which corresponds to an overall conversion efficiency of 4.54%. The lower efficiency of these seven dyes compared to literature reports (η=9%) may be ascribed to the lack of broad absorption in the visible spectrum. These results imply that sensitizer, which use cyanoacetic acid as electron-withdrawing part , introducing a secondary electron-donating group and is a possible alternative to give high electron injection efficiency and charge separation efficiency.