Characterization of Planar Lead Halide Perovskite Solar Cells by Impedance Spectroscopy, Open-Circuit Photovoltage Decay, and Intensity-Modulated Photovoltage/Photocurrent Spectroscopy
Characterization of Planar Lead Halide Perovskite Solar Cells by Impedance Spectroscopy, Open-Circuit Photovoltage Decay, and Intensity-Modulated Photovoltage/Photocurrent Spectroscopy
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DOI：
10.1021/jp510837q
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发表时间：
2015-02-19
影响因子：
3.7
通讯作者：
Cameron, Petra J.
中科院分区：
文献类型：
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作者：
Pockett, Adam;Eperon, Giles E.;Cameron, Petra J.
薄膜卤化铅钙钛矿电池（其中钙钛矿层直接沉积在平坦的二氧化钛阻挡层上）已经达到超过15%的AM 1.5效率，（1）表明在早期类型的钙钛矿太阳能电池中使用的中孔支架不是必需的。我们使用了各种技术来更好地了解通过基于溶液的方法制备的薄膜钙钛矿电池。研究了12个电池，其显示AM 1.5效率类似于11%。使用阻抗谱、强度调制光电压谱（IMVS）、强度调制光电流谱（IMPS）和开路光电压衰减（MOCVD）研究了电池的性质。尽管所有12个细胞都是在名义上相同的条件下同时制备的，但它们的行为分为两组。一半的细胞表现出理想因子m接近2.5，另一半表现出理想因子m接近5。在开路照明下进行的一系列强度的阻抗谱表明，电池电容主要由钙钛矿层的几何电容，而不是由于光生载流子的化学或扩散电容。复合电阻的电压依赖性给出了与开路电压的强度依赖性类似的理想因子。IMVS时间常数由几何电容和复合电阻的乘积确定。这两种类型的细胞给出了非常不同的OCVD反应。m值接近2.5的细胞表现出持续的光电压效应，而理想因子较高的细胞则没有这种效应。IMPS响应提供了短路条件下复合导致的微小效率损失的证据。
Thin film lead halide perovskite cells, where the perovskite layer is deposited directly onto a flat titania blocking layer, have reached AM 1.5 efficiencies of over 15%,(1) showing that the mesoporous scaffold used in early types of perovskite solar cells is not essential. We used a variety of techniques to gain a better understanding of thin film perovskite cells prepared by a solution-based method. Twelve cells were studied, which showed AM 1.5 efficiencies of similar to 11%. The properties of the cells were investigated using impedance spectroscopy, intensity-modulated photovoltage spectroscopy (IMVS), intensity-modulated photocurrent spectroscopy (IMPS), and open-circuit photovoltage decay (OCVD). Despite the fact that all 12 cells were prepared at the same time under nominally identical conditions, their behavior fell into two distinct groups. One half of the cells exhibited ideality factors of m approximate to 2.5, and the other half showed ideality factors of m approximate to 5. Impedance spectroscopy carried out under illumination at open circuit for a range of intensities showed that the cell capacitance was dominated by the geometric capacitance of the perovskite layer rather than the chemical or diffusion capacitance due to photogenerated carriers. The voltage dependence of the recombination resistance gave ideality factors similar to those derived from the intensity dependence of the open-circuit voltage. The IMVS time constant was determined by the product of the geometric capacitance and the recombination resistance. The two types of cells gave very different OCVD responses. The cells with m approximate to 2.5 showed a persistent photovoltage effect that was absent in the case of the cells with higher ideality factors. The IMPS responses provide evidence of minor efficiency losses by recombination under short-circuit conditions.