Photoelectric Transmission Mechanism Of Organic Dyes Sensitizing Agent

To solve the problem of silicon solar cell,such as higher material cost,complex industrial manufacturing process,not conducive to environmental protection and other issues,new type of thin film solar cells-dye sensitized solar cell(DSSC)arises at the historic moment.As the core of the DSSC cell composition,dyes sensitizers have a direct impact on the whole photoelectric performance of the battery device.So the research and development of efficient dyes sensitizers have become the most important thing for each personnel worker in the DSSC battery field.Organic dye sensitizing agent is divided into two kinds:natural acquisition and artificial synthesis.The photoelectric performance of synthetic sensitizer is better,however compared with the department of silicon solar cell,the conversion efficiency has an obvious gap.Furthermore,organometallic sensitizers still have higher cost and resource scarcity problems.Natural dyes are abundant and cheap,but the conversion efficiency is very low and people know little about the mechanism.In this paper,the light absorption characteristics and charge transfer properties of synthesized organic non-metallic dye molecules and natural dye molecules were studied.The main contents are summarized as follows:(1)Using density functional theory(DFT)and the time-dependent density functional theory(TDDFT)method to study the different directions of thiophene pyrrole group for D-D-?-A type of dye molecules with different photoelectric conversion efficiency.The ground state structure,the frontier molecular orbitals and electron density distribution,absorption spectrum and the important parameters associated with the photoelectric conversion efficiency of M45 and M46 molecules in vacuum and dichloromethane solvent were calculated.Calculation results show that the introduction direction of the thiophene pyrrole group significantly affects the distortion degree of the molecular structure.Due to the better coplanar on the second donor,M45 molecule shows a more extensive range of spectral absorption and better electronic energy level structure.In addition,the study of the dye molecules in the two designed groups further verify that the different coupling modes of the electronic groups will have an effect on the molecular structure,and the less distorted structure will benefit the charge transfer.(2)The photophysical properties of beta carotene and zeaxanthin were studied in theory and experiment.The UV-Visible absorption spectra,Fourier infrared spectra and current-voltage characteristic curves of several dyes were tested.We use DFT and TDDFT methods to calculate the frontier molecular orbitals,absorption spectra,electron injection driving force and optical trapping efficiency of several dyes.The results show that,the hydroxyl group of zeaxanthin have been chemically adsorbed with titanium dioxide film,and the charge transfer is more stable and powerful.In addition,the total scope of the visible spectrum response of co-sensitized dye solution has been greatly improved.Intermolecular charge transfer effect effectively made up for the narrower absorption band of the single dye and enhance the action of dye molecules and titanium dioxide films.