Septina Wilman, Sugimoto Minori, Chao Ding, Shen Qing, Nakatsuka Shigeru, Nose Yoshitaro, Harada Takashi, Ikeda Shigeru
Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
Phys Chem Chem Phys. 2017 May 17;19(19):12502-12508. doi: 10.1039/c7cp01348e.
The effects of partial replacement of Cu with Ag in a Cu(In,Ga)S (CIGS) thin film on its structural, optical, electrostructural, and photoelectrochemical (PEC) properties were investigated, in order to improve its performance for PEC water reduction under sunlight illumination. Results from X-ray diffraction (XRD) analyses revealed the successful partial replacement of Cu with Ag to form solid-solutions with different Ag/(Ag + Cu) ratios (A(x)CIGS, x = Ag/(Ag + Cu) = 0.1, 0.2, 0.3 and 0.4), as confirmed by a gradual change in the (112) reflections to smaller 2θ angles with increasing Ag/(Ag + Cu) ratio. Analyses of the photoabsorption properties of the materials using photoacoustic spectroscopy indicated changes in the band gap energies associated with increasing the Ag/(Ag + Cu) ratio. In addition, valence band maximum potentials of A(x)CIGS were deepened gradually with increasing Ag/(Ag + Cu) ratio. After modifying these A(x)CIGS films with a CdS ultrathin (ca. 70 nm) layer and a Pt catalyst, the PEC water reduction properties were evaluated in an electrolyte solution with the pH adjusted to 6.5, under simulated sunlight (AM 1.5G) radiation. Compared to the CdS- and Pt-modified Ag-free A(x)CIGS (A(0)CIGS) films, appreciable enhancements in the PEC properties were observed for electrodes based on A(x)CIGS (x > 0) films, and the best PEC performance was obtained for the electrode based on the A(0.2)CIGS film. However, the electrode derived from the A(x)CIGS film with Ag/(Ag + Cu) ratios higher than 0.3 showed diminished PEC properties due to the partial conversion of its semiconducting properties from p-type to n-type.
研究了在Cu(In,Ga)S（CIGS）薄膜中用Ag部分替代Cu对其结构、光学、电结构和光电化学（PEC）性能的影响，以提高其在阳光照射下PEC水还原的性能。X射线衍射（XRD）分析结果表明，Ag成功地部分替代了Cu，形成了具有不同Ag/(Ag + Cu)比率（A(x)CIGS，x = Ag/(Ag + Cu) = 0.1、0.2、0.3和0.4）的固溶体，这通过(112)反射随着Ag/(Ag + Cu)比率增加向较小2θ角的逐渐变化得到证实。用光声光谱对材料的光吸收性能进行分析表明，带隙能量随着Ag/(Ag + Cu)比率的增加而变化。此外，A(x)CIGS的价带最大电位随着Ag/(Ag + Cu)比率的增加而逐渐加深。在用CdS超薄（约70 nm）层和Pt催化剂对这些A(x)CIGS薄膜进行改性后，在pH值调节为6.5的电解质溶液中，在模拟阳光（AM 1.5G）辐射下评估了PEC水还原性能。与CdS和Pt改性的无Ag A(x)CIGS（A(0)CIGS）薄膜相比，基于A(x)CIGS（x > 0）薄膜的电极在PEC性能方面有明显增强，基于A(0.2)CIGS薄膜的电极获得了最佳PEC性能。然而，来自Ag/(Ag + Cu)比率高于0.3的A(x)CIGS薄膜电极的PEC性能有所下降，这是由于其半导体性能从p型部分转变为n型。
