Origin of enhancement in open-circuit voltage by adding ZnO to nanocrystalline SnO2 in dye-sensitized solar cells.
Origin of enhancement in open-circuit voltage by adding ZnO to nanocrystalline SnO2 in dye-sensitized solar cells.
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DOI：
10.1021/jp051753g
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发表时间：
2005-09
期刊：
影响因子：
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通讯作者：
Daisuke Niinobe;Yuki Makari;T. Kitamura;Y. Wada;S. Yanagida
中科院分区：
文献类型：
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作者：
Daisuke Niinobe;Yuki Makari;T. Kitamura;Y. Wada;S. Yanagida
将纳米二氧化锡胶体分散体与氧化锌或锌(CH3COO)2混合制成SnO2+氧化锌染料敏化太阳能电池工作电极。相对于只含SnO2的电池，添加氧化锌或锌(CH3COO)2提高了电池的开路电压(V(Oc))。电极中电子寿命与短路光电流密度(J(Sc))的关系证明，锌的加入抑制了反向电子向电解液的转移是提高V(Oc)的原因。V(Oc)对温度的依赖关系表明，混合电极的结合电容降低。V(Oc)依赖于J(Sc)的对数的斜率表明，带的解钉扎对V(Oc)增强的贡献可以忽略不计。从电极的循环伏安曲线看，混合电极的结合电容比SnO2的小1个数量级。混合电极中结合电容的减小可以用SnO2的化学电容减小，从而使导带位置向真空水平移动来解释。Sn3d(5/2)峰的X射线光电子能谱表明，随着锌加入量的增加，Sn3d(5/2)峰向低结合能方向移动。这归因于表面电势朝着负方向的增加，这可能是由于锌在SnO2表面形成的偶极矩所致。
SnO2 + ZnO working electrodes for dye-sensitized solar cells were made by mixing a nanocrystalline SnO2 colloidal dispersion with ZnO or Zn(CH3COO)2. Addition of ZnO or Zn(CH3COO)2 enhanced the open-circuit voltage (V(oc)) of the cells with respect to cells containing only SnO2. Dependence of the electron lifetime in the electrodes on short-circuit photocurrent density (J(sc)) gave evidence against the assumption that the suppression of back electron transfer to the electrolyte is the origin for the V(oc) enhancement by addition of Zn. V(oc) dependence on temperatures indicated a decrease in the combined capacitance of the mixed electrode. The slope of the V(oc) dependence versus the logarithm of J(sc) indicated that the contribution of unpinning of the band to the enhancement of V(oc) could be neglected. From the cyclic voltammograms of the electrodes, the combined capacitance of the mixed electrode was 1 order of magnitude smaller than that of SnO2. The decrease in the combined capacitance in the mixed electrode could be explained by the decrease in the chemical capacitance of SnO2, thus the shift of the conduction band position toward the vacuum level. X-ray photoelectron spectra of Sn 3d(5/2) peaks showed a shift toward lower binding energy with an increasing amount of added Zn. This was attributed to an increase in the surface potential toward the negative direction, which might have resulted from a dipole moment formed by Zn on the surface of SnO2.