| Recently,human is facing the crisis of fossil energy exhaustion,and the best way to solve this crisis is to use solar energy.Since dye-sensitised solar cell was discovered in 1991,it has been attracted a large number of researches to study due to its simple constructure,easy preparation,convenient raw materials,green and environmental friendly.However,the difference should not be ignored of the conversion rate and the stability between the traditional silicon semiconductor solar cell and dye-sensitized solar cells(DSSCs).There are two different reasons to restrict batteries’ efficiency.Firstly the absorption of the full spectrum of sunlight cannot be achieved.For example the mainly absorption range of dye N719 in common using is ranged from 400-600 nm in visible light,other wavelengths of light will be wasted.Secondly photo-induced electrons may recombine with the oxidation state ions in the electrolyte,so electrons will be exhausted during the transport process in the battery.In order to prepare more excellent dye-sensitized solar cells,this paper explores two aspects.On the one hand,the appropriate luminescent materials were prepared and utilized to widen the N719 absorption spectrum,on the other hand the constructure of the TiO2 membrane layers were optimized through the combination of different morphology TiO2 layer to suppress the recombination of charges.Main research contents are as follows:1.ZnO:Ga3+ down conversion luminescence material was prepared by Ga2O3 doping at 1100 ℃ for 6 hours.This luminescence material shows a broad peak emission ranged from 450-600 nm by 385 nm ultraviolet excitation,the emission peak is at 525 nm.Broad peak emission originate from the recombination of Ga3+ which as the shallow donor level with the Oi in ZnO and oxygen vacancy which captured raw electronic recombine with the ZnO valence band holes.By changing the Ga3+ doping amount,the luminous intensity of luminescence materials with the increase of doping amount reduced after rising first,when the doping concentration is 12 mol%,obtained the best luminous intensity.Through adding 5 wt%ZnO:Ga3+ into TiO2 photo anode,battery short circuit current density reached 11.38 mA cm-2,increased 14.2%compared with undoped samples,the photoelectric conversion efficiency enhanced from 4.24%to 4.91%,increased by 15.8%.2.The down conversion luminescence material of(Ca1-x ySrxEuy)7(SiO3)6Cl2 was prepared at 950℃ for 10 hours in reducing atmosphere.The result shows that 490 nm Eu2+(5d→4f)green emission,Eu3+ 610 nm(5D0→F2),and 650 nm(5D→2F3)red emission were caused by 360 nm and 465 nm excitation respectively.The elements of Mg and Ba were used to replace the Ca of the matrix to enhance yellow and green light emission,leading to reduce the red light emission.The emission spectrum of the luminescence material should be more suitable for N719 absorption range of visible light.Through adding 1wt%(Ca1-x-ySrxEuy)7(SiO3)6Cl2 into Ti02 photo-anode,the short circuit current density enhance from 8.989 mA·cm-2 to 10.30 mA·cm-2,elevate 14.6%.Photoelectric conversion efficiency enhanced from 4.24%to 4.91%increased by 15.8%.3.The compact TiO2 barrier layer and light scattering layer with the large particles of TiO2 were introduced into photo-anode through TiCl4 hydrolysis and the twice scratch technique.The TiO2 dense layer can effectively suppress the photo production electronic recombination and enhance battery short circuit,photoelectric conversion efficiency significantly in the condition of TiCl4 solution concentration is 0.05 M and holding time is 30 min.When the thickness of introduction larger particles TiO2 scattering layer is around 10 mm,the scattering layer scatter incident light effectivity,increase the optical path length and the probability of dye molecules absorb photon,promoting the utilization rate of the incident light so as to improve the performance of the battery.Through TiO2 compact layer and the scattering layer introduced together,the battery short circuit current density increased from 14.159 mA·cm-2 to 17.044 mA·cm-2,elevate 20.3%.Battery conversion efficiency was increased from 6.288%to 7.073%,improved by 12.5%. |
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