| ZnO is wide bandgap semiconductor material,compared with TiO2,it has near physical and chemical properties.As a photoelectrode material,ZnO possesses a wide energy band gap similar to that of TiO2.At the same time the electron mobility in the ZnO film is greater than in the TiO2 thin film,electron transport time in the ZnO film can be reduced.And preparation process of ZnO nanopowders is simple and low cost.ZnO morphology is rich than TiO2's,the different morphologies of the ZnO nanopowders can be prepared in chemical method at low temperature.ZnO can be promissing anode material of dye sensitization solar cell(DSSC),however ZnO can react with common acid N719 dye and N3,Zn2+/dye oligomer,and the oligomer filled into the pores of ZnO anodes,reduced the adsorption of dye and the oligomer easily gathered at the same time to form a thick barrier layer,block the electron injection,lead to the low photoelectric conversion efficiency.In this paper,Li+ doping of ZnO powders and the influence of Li+dope in ZnO based dye sensitization solar cell were studied.(1)ZnO nanoparticles and anode film prepared with Zn(NO3)2·6H2O and Na2CO3 as raw material,in order to study the influence of different N719 dye concentrations and different immersion time on ZnO based DSSC,the optimal system is 0.05 mM N719 dye concentration and 1h immersion time,the photoelectric conversion efficiency of ZnO nanoparticles DSSC:the open circuit voltage was 0.70 V,short circuit current was 3.2 mA · cm2,fill factor was 0.52,the photoelectric conversion efficiency was 1.17%.(2)ZnO nanoparticle aggregagetes(200-800 nm aggregates composed of 30 nm particles)were prepared as following process:water-bath in 160? with[Zn(AC)2·2H2O]and[C4H10O3]as raw materials.Reactive time were studied,when reactive time was 6h,ZnO nanoparticles aggregates based DSSC:open circuit voltage was 0.66 V,short circuit current was 5.98 mA·cm2,fill factor was 0.48,the photoelectric conversion efficiency was 1.91%.The influence of different Li+ doping molar concentration on the ZnO nanoparticle aggregates'property were systematic studied.Results showed that 0.01M was appropriate doping amount of Li+,then different doping time with 0.01M Li+ were studied,the optimum doping time was 50 min.Li+ doped ZnO nanoparticle aggregates based DSSC photoelectric conversion efficiency was 2.56%,the open circuit voltage was 0.65V,short circuit current was 8.14 mA·cm2,fill factor was 0.48,the photoelectric conversion efficiency increased by 67%than none Li+ doped ZnO nanoparticle aggregates based DSSC.(3)ZnO nanosheet aggregates were prepared under direct precipitation:Zn(NO3)2·6H2O solution add into NaOH solution.ZnO nanosheets aggregates preparation under ultrasonic process and Li+ doping was better.The Li+ doped ZnO nanosheets aggregate based DSSC:the open circuit voltage was 0.66 V,short circuit current was 6.2 mA ·cm2,fill factor was 0.52,the photoelectric conversion efficiency was 2.14%.(4)Two different preparation technics,precipitating the Zn(NO3)2·6H2O and NaOH solution directly or in ultrasonic condition,were applied.And the effect of preparation technics and the amount of Li+-doping on ZnO nanosheet aggregates and the properties of DSSC were studied.The Li+-doping either in direct precipitation condition or in ultrasonic condition can both effectively improve the performance of the DSSC.The photoelectric conversion efficiency,open-circuit voltage,short-circuit current and fill factor of Li+-doping DSSC in direct precipitation condition were 1.27%,0.58V,3.80 mA·cm-2,and 0.58,respectively.Compared with the DSSC without Li+-doping,the photoelectric conversion efficiency of Li+-doping DSSC in direct precipitation condition improved 52%.(5)In the preparation of nanosheets aggregates under the condition of ultrasonic,,Zn2+ = 0.1 M,the effects of Li+ concentration(0.005 M,0.01 M,0.02 M,0.04 M and 0.08 M)on the properties of ZnO nanosheets aggregates and DSSC.When the concentration was 0.01 M,0.02 M,0.04 M and 0.08 M can improve the performance of the battery.The effect of different Li+-doping amount on the performance of DSSC in ultrasonic condition was studied.When the Li+-doping amount was 0.04M,the photoelectric conversion efficiency,open-circuit voltage,short-circuit current and fill factor of the cell were 2.14%,0.66V,6.20mA·cm-2 and 0.52,respectively.Compared with the DSSC without Li+-doping,the photoelectric conversion efficiency of Li+-doping DSSC in ultrasonic condition also improved 52%.(6)Zn2+ concentration(0.1M and 0.2M)was studied under the condition of ultrasonic precipitation.ZnO nanosheets aggregates based DSSC(Zn2+=0.1,Li+=0.04)photoelectric conversion efficiency was 2.14%better than ZnO nanosheets aggregates based DSSC(Zn2+=0.1,Li+=0.04),which was 1.82%... |
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