Effect of copper content and sulfurization process on optical, structural and electrical properties of ultrasonic spray pyrolysed Cu2ZnSnS4 thin films
Effect of copper content and sulfurization process on optical, structural and electrical properties of ultrasonic spray pyrolysed Cu2ZnSnS4 thin films
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DOI：
10.1016/j.matchemphys.2015.11.035
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发表时间：
2016-02-01
影响因子：
4.6
通讯作者：
Duta, Anca
中科院分区：
文献类型：
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作者：
Kermadi, S.;Sali, S.;Duta, Anca
本文报道了铜含量和硫化过程（使用元素硫蒸气）对使用超声波喷雾热解沉积在玻璃基板上的 Cu2ZnSnS4 (CZTS) 薄膜的生长、结构、元素组成以及光学和电学性能的影响。为此，制备了一系列由氯化铜 (II) 和氯化锡 (IV)、乙酸锌 (II) 和硫脲组成的不同铜浓度（x = Cu/(Zn + Sn) = 0.8、1、1.2 和 1.4，而 Zn/Sn = 1）的水溶液。使用 X 射线衍射、拉曼光谱、扫描电子显微镜、原子力显微镜、能量色散 X 射线光谱、紫外可见近红外吸收光谱和薄层电阻分析来跟踪所研究性能的演变。结果显示了锌锡矿型 CZTS 相和二次硫化铜 (Cu2-xS) 相，它们的比例很大程度上取决于铜盐浓度和热处理气氛。当 x = 1.2 的硫化后薄膜获得高纯度 CZTS 时，没有发现锌或锡硫化物的二次相痕迹。研究发现，额外硫化的应用可促进晶粒生长，使其尺寸达到 300 nm，并显着改善 CZTS 结晶度和电导率。光学带隙范围在 1.44 至 1.57 eV 之间，具体取决于成分，并且与在氮气气氛中退火的化合物相比，硫缺陷大大减少，导致铜含量较低且锌含量较高的化合物。这项研究显示了有希望的结果，作为开发光伏应用的第一步，使用喷涂的 CZTS 作为吸收剂。 (C) 2015 Elsevier B.V. 保留所有权利。
This paper reports the effect of copper content and of the sulfurization process (using elemental sulfur vapor) on the growth, structure, elemental composition, and on the optical and electrical properties of Cu2ZnSnS4 (CZTS) thin films deposited on glass substrates using ultrasonic Spray Pyrolysis. For this purpose, a series of aqueous solutions consisting of copper (II) and tin (IV) chlorides, zinc (II) acetate and thiourea with different copper concentrations (x = Cu/(Zn + Sn) = 0.8, 1, 1.2 and 1.4 while Zn/Sn = 1) were prepared. X-ray diffraction, raman spectroscopy, scanning electronic microscopy, atomic force microscopy, energy dispersive X-ray spectroscopy, ultraviolet visible near infrared absorbance spectroscopy and sheet resistance analyses were used to follow the evolution of the investigated properties. The results outlined a Kesterite type CZTS phase and a secondary copper sulfide (Cu2-xS) phase, and their ratio strongly depends on the copper salt concentration and heat-treatment atmosphere. No traces of secondary phases of zinc or tin sulfides are found while high purity CZTS was obtained with the post-sulfurized film at x = 1.2. It was found that the application of additional sulfurization enhances the grain growth to reach 300 nm in size and induces significant improvement of both CZTS crystallinity and electrical conductivity. The optical band gap ranges between 1.44 and 1.57 eV depending on the composition and the sulfur deficiency is strongly reduced leading to Cu-poorer and Zn-richer compounds, as compared to those annealed in nitrogen atmosphere.This study shows promising results, as a first step in developing photovoltaic applications, using sprayed CZTS as absorber. (C) 2015 Elsevier B.V. All rights reserved.