| Organic dye is the important part in organic dye sensitized solar cells?DSSCs?.And the better performance organic dyes are beneficial to improve the performance of DSSCs.Designing the efficient organic dyes is the significant method to obtain the high efficiency of DSSCs.In this work,a series of D-A-?-A organic dyes had been designed and density functional theory?DFT?and time-dependent density functional theory?TDDFT?were used to analyze the electronic structures,energy levels,and absorption spectra of these dyes.The excited states of these dyes also be considered in this paper.The main content of this work is as follows:1.Based on the experimental synthesized D-A-?-A organic dye JZ145 by Xiongwu Kang etc.,we designed SPL201-SPL213 D-A-?-A organic dyes by changing the additional acceptor group,p-conjugated bridge and acceptor group.The computational results indicate that SPL212 not only has a large extent of redshifs in absorption spectra,but also extends to near-infrared light of 1200nm.Compared with JZ145,the maximum molar extinction coefficient of SPL212 improved greatly.The longer lifetime of excited state and the better higher ability of light absorption show that SPL212 may be a promising dye in high efficient DSSCs.2.-CN is a strong electron-withdrawing group,which is used as D-A-?-A organic dyes with carboxylic acid.Based on JZ145,ME15-ME17 were designed with no-CN,one-CN or two-CN in this part.The results show that one-CN in acceptor group is beneficial to intramolecular charge transfer and electron injection to TiO2semiconductor.3.In this part,two types of D-A-?-A organic dyes had been designed.ME31-ME34 are the long wavelength absorption dyes,and the results indicate that the maximum absorption of ME31 and ME33-ME34 are in the region of infrared light.ME35-ME40 are the dyes with different halogen atoms.The results indicate that the halogen atoms cause negligible effects on the absorption ability,and the F atom is recommended in the auxiliary electron withdrawing group. |
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