ZnO-Based Dye-Sensitized Solar Cells And Scaling-Up Research

This paper reported the fabrication of hierarchically-structuredpolydisperse ZnO aggregates as an effective photoelectrode fordye-sensitized solar cells （DSCs）. After optimizing the preparationconditions, it compared the performance of ZnO-DSCs utilizingmetal-free organic dyes D149and ruthenium complexes N719dye assensitizers. It also reported the preparation process of large area DSCsdevice. According to our research D149may be developed as apromising sensitizer for high-efficiency ZnO-DSCs towards thecommercial application.The ZnO aggregates were prepared by hydrolyzing zinc acetatedehydrate （99.5%Zn（OAc）₂·2H₂O） in diethylene glycol （99%DEG） toobtain polydisperse aggregates. The ZnO photoanodes were fabricated bydoctor-blade technique on FTO substrates followed by optimizing thepreparation process effectively. The optimized DSCs were obtained whenthe film suffered a programmed heating of350°C （1h） followed by risingto450°C at10°C/min at the thickness of16um.Based on the optimized conditions a deep comparative research onD149and N719sensitized ZnO-DSCs was investigated. The maximumenergy conversion efficiencies of ZnO-DSCs sensitized by D149andN719reached to5.2%and4.5%, respectively. UV-Visible spectra（UV-Abs） electrochemical impedance spectroscopies （EIS） and incidentphotons to current conversion efficiency （IPCE） were characterized tocompare the optical properties, the IPCE value and electron transfer interface resistance. The higherηof D149-based DSCs than N719-basedDSCs is caused by three reasons1) the molar extinction coefficient ofD149is almost five times higher than N719dyes2) IPCE value ofD149-DSCs reached66%much higher than49%of N719-DSCs3)interface resistance of ZnO/D149/electrolyte is15.5lower than21.3for that of ZnO/N719/electrolyte.Moreover we reported the preparation technology of large areaDSCs device. The internal parallel TiO2-DSCs with active area of19.2cm²reached efficiency of3.0%the monolithic ZnO-DSCs modules wereprepared and sensitized by D149and N719respectively. D149-and theN719-ZnO DSCs module with active area of2.4cm2reached efficiencyof2.6%and2.4%respectively.The research has important guiding significance dye moleculesengineering and the practical application of the solar cells.