电化学阻抗谱研究聚合物凝胶电解质对染料敏化太阳能电池性能的影响

Influence of Polymer Gel Electrolyte on the Performance of Dye-Sensitized Solar Cells Analyzed by Electrochemical Impedance Spectroscopy

用甲基丙烯酸β-羟乙酯(HEMA)与N-乙烯基吡咯烷酮(NVP)共聚物P(HEMA-NVP)、甲基丙烯酸甲酯(MMA)与N-乙烯基吡咯烷酮共聚物P(MMA-NVP)为原料制备了聚合物凝胶电解质,用电化学阻抗谱(EIS)研究了聚合物凝胶电解质中聚合物基质的结构与组成对准固态染料敏化太阳能电池(DSSCs)光伏性能的影响.不同交联剂用量、不同HEMA用量的P(HEMA-NVP)共聚物及不同MMA用量的P(MMA-NVP)吸收液态电解质后分别形成HGelI、HGelII、MGel凝胶电解质.结果发现,随共聚物P(HEMA-NVP)中交联剂由0.1%(w,下同)增大到0.6%时,形成的HGelI组装的DSSCs的光电转化效率(η)先增大后降低,交联剂用量为0.4%时,DSSCs的η为最大,为5.54%(光强100mW.cm-2).同时,比较HGelII系列和MGel系列DSSCs的光电性能参数发现,含有羟基的HGel系列的η要高于MGel系列,而后者的开路电压(Voc)值高于前者.在HGelII系列中,HEMA含量为60%(w)时,DSSCs的η最高.电化学阻抗谱分析表明共聚物中交联结构的不同影响了电池内部的界面阻抗及离子的传输,引入羟基有利于降低界面阻抗.通过调整共聚物中交联剂用量和羟基含量可改善DSSCs的光伏性能.

The effects of gel electrolyte polymer matrix structure and composition on the photovoltaic properties of quasi-solid state dye-sensitized solar cells （DSSCs） were investigated using two series of copolymers, poly（hydroxy ethyl methacrylate-N-vinyl） pyrrolidone P（HEMA-NVP） and poly（methyl methacrylate- N-vinyl pyrrolidone） P（MMA-NVP）, by electrochemical impedance spectroscopy （EIS）. P（HEMA-NVP） copolymers with various crosslinking agent and N-vinyl pyrrolidone （NVP） contents, as well as P（MMA-NVP） copolymers with various NVP content, absorbed liquid electrolyte to form gel electrolytes HGelI, HGelII, and MGel, respectively. It was found that with increasing copolymer P（HEMA-NVP） crosslinking agent content, from 0.1 to 0.6% （w）, the power conversion efficiency （η） of DSSCs based on HGelI initially increased and then decreased. A maximum conversion efficiency of 5.54% at 100 mW·cm-2 was observed when crosslinker content was 0.4% （w）. Meanwhile, we compared the parameters of DSSCs based on HGelII with those of DSSCs based on MGel. The conversion efficiencies of the former, which contained hydroxy groups, were all higher than those of the latter, while the open circuit voltages （Voc） of the latter were larger than those of the former. DSSCs assembled with HGelII with a HEMA content of 60% exhibited the highest conversion efficiency, at 100 mW·cm-2. Electrochemical impedance spectroscopy （EIS） investigations showed that copolymer crosslinking structure affected the internal resistance and ionic conductivity of the resulting DSSCs, while addition of hydroxy groups decreased the interfacial resistance. Thus, the photovoltaic performance of DSSCs can be improved by tuning the crosslinking structure and the hydroxy content of the copolymer.