Study On Photoelectric Properties Of Triphenylamine And Phenothiazine Dyes

The combustion of traditional fossil energy will bring environmental pollution and energy crisis,while solar energy has attracted attention because of its environmental friendliness.There are many types of solar cells,including silicon-based solar cells and thin-film solar cells.Since the third-generation photovoltaic dye-sensitized solar cells（DSSCs）proposed by Gr?ztel,they have been favored for their low cost,easy synthesis,and environmental friendliness.Research on the mechanism and structure design in molecular engineering provides ideas for improving photovoltaic performance and an effective way to find an alternative renewable energy technology to meet the current energy demand.In the first part,we investigated the electronic and photovoltaic properties of four triphenylamine dye molecules（AP25,AP26,AP27,AP28）using density functional theory（DFT）and time-dependent density functional theory（TD-DFT）.Dyes mainly include the triphenylamine（T）derivatives as donors,combined with different cyclopentathiophene（CPDT）and quinolone（QA）conjugated bridges and auxiliary acceptor groups thiophenethiophene（TT）and benzothiadiazole（BTZ）.Microscopic parameters related to open-circuit voltage(V_oc)and short-circuit current density(J_sc)were calculated and compared.The results showed that AP27dye formed by CPDT-bridge and BTZ coreceptor is the most promising design for improving performance because the molecular absorption spectrum of AP27 has a redshift absorption,and this molecule has greater LHE,longer fluorescence lifetime（τ₁）and excited state lifetime（τ₂）andμ_normal.Therefore,the molecular design of regulating molecular conjugated bridges and auxiliary receptors contributes to the improvement of the photoelectric properties of dyes.In the second part,we also investigated the electronic and photovoltaic properties of five phenothiazine-based dyes using DFT and TD-DFT methods.The molecular structures are constructed by introducing a carbazole unit as a donor and phenothiazine（PTZ）as the bridge linking with different designed acceptors.We analyzed the dye molecule’s ground state and electronic structure,energy level and energy gap,excited state properties,chemical reaction parameters,recombination energy,charge transfer,dipole moment and dye regeneration process.The results show that the CBPTZ-BTD6 dye molecule has a lower energy gap value due to better electron-withdrawing ability,better LHE,enhancedμ_normal,better regeneration energy and chemical reaction parameters,which can strengthen the photoelectric performance.This study provides a molecular design idea for designing high-performance DSSCs by modifying receptors.