Effect Of Functional Group Regulation On Photoelectric Properties Of Zinc Porphyrin Dye Mol Ecules

With the continuous growth of the population,the energy demand was increasing all over the world.The excessive dependence on and exploitation of traditional energy also aggravated the problems of the greenhouse effect and environmental pollution.As the low-cost and pollution-free photovoltaic technology,Dye sensitive solar cells(DSSCs)showed great potential in clean energy.Porphyrins,as sensitized molecules of DSSCs,had the advantages of a wide absorption spectrum,a large absorption coefficient and easy regulation of molecular structure,which had been widely concerned in many sensitizer studies.Firstly,the zinc porphyrin dyes(LG-t T and LG-Dt T)were theoretically calculated by density functional theory(DFT)and time-dependent density functional theory(TD-DFT).To theoretically study the effect of thieno-thiophene and dithieno-thiophene as auxiliary acceptors on the photoelectric properties of zinc porphyrins,the optimized structure,the frontier molecular orbital(FMO),absorption spectrum,hyperpolarizability,electrochemistry,charge difference density(CDD)and interfragment charge transfer(IFCT)of the two dye sensitizers were calculated.This explained why LG-t T dye had better performance than LG-Dt T in the experiment.In addition,five zinc porphyrin sensitizers LG-t T-(A,B,a,b,c)with different auxiliary acceptors were designed to explore strategies to improve the performance of sensitizers.The results showed that,among all designed molecules,LG-t T-a with thiadiazopyridine as auxiliary acceptor exhibited the most obvious intramolecular charge transfer(ICT)characteristic,the strongest light capture ability and the higher short-circuit current(J_SC)and open-circuit voltage(V_OC).Secondly,to explore the effects of different donors on the photoelectrical properties of fused porphyrin dyes,the ten different donor structures of fused porphyrin dyes were theoretically studied by DFT and TD-DFT.The results showed that the changes in donor structures mainly affected the highest occupied molecular orbital(HOMO)energy level,but it had almost no effect on the lowest unoccupied molecular orbital(LUMO).A series of dyes containing triphenylamine donors showed excellent electrochemical parameters and ICT characteristics compared with a series of dyes containing phenothiazine donors and experiments of dyes.Df Zn P-(2B,2C,2D)had improved solar utility efficiency and band edge movement,which could lead to its higher photoelectric parameters.Therefore,reasonable modification of molecular structure would effectively improve the photoelectric conversion performance of dyes.This study provides important theoretical support for functional groups regulating the photoelectric properties of porphyrin dyes.