负偏压作用下染料敏化太阳电池界面及光电性能研究

太阳电池组件由于局部电压不匹配,其中部分电池可能较长时间工作在负偏压状态下,从而影响电池光电性能.借助拉曼光谱、电化学阻抗谱和入射单色光量子效率(IPCE)等测试手段,研究长期负偏压作用下染料敏化太阳电池光电性能的变化及其影响机理.拉曼光谱研究结果表明:电池在1000 h负偏压作用下,电解质中阳离子(Li⁺)会向光阳极(TiO₂电极)移动并嵌入TiO₂薄膜中;长期负偏压作用还会致使TiO₂/电解质界面阻抗增大和IPCE下降,导致电池开路电压升高和短路电流减小.通过加入苯并咪唑(BI)添加剂,经1000 h负偏压后电池的拉曼光谱实验表明,BI能在一定程度阻碍Li⁺的嵌入,电池具有较好的长期稳定性.不同负偏压下的老化实验进一步表明,通过加入添加剂能够使电池在长期负偏压下保持较好的稳定性. 关键词： 染料敏化 太阳电池 组件 负偏压

The study of interface and photoelectric performance of dye-sensitized solar cells in the applied negative bias

Dye-sensitized solar cell (DSC) modules are most likely to work for long time under negative bias due to the mismatch in the outdoor usage, which can obviously influence the cell performance. In this paper, the interface property of DSC under negative bias is investigated by Raman spectroscopy, electrochemical impedance spectroscopy and incident-photon-to-electron conversion efficiency (IPCE). The results of Raman spectroscopy indicate that the decreased peak intensity at 167 cm^-1 (the oxidized state of N719 (D⁺)/ I₃^-) after 1000 h could be due to Li⁺ ions diffusing into the TiO₂ electrode and partially being intercalated into the TiO₂ film. It is also found that the increased recombination resistance in the interface of TiO₂/electrolyte resultes in the improved open-circuit voltage and the decreased IPCE values, leading to reduced short-circuit current for DSC with base electrolyte under the long-term negative bias. However, when BI is added into the base electrolyte, the Raman spectrum shows no significant change and that the cell efficiency remains stable after 1000 h. The reason is that BI could prevent Li⁺ ions from being intercalated into the TiO₂ film. It is proven by the further experiments where the DSC with BI exhibits better stability under different negative biases.