One-step synthesis of Cu2ZnSnS4 thin films by reactive magnetron co-sputtering
One-step synthesis of Cu2ZnSnS4 thin films by reactive magnetron co-sputtering
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DOI：
10.1016/j.actamat.2015.06.001
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发表时间：
2015-09
期刊：
影响因子：
9.4
通讯作者：
Pierre-Antoine Cormier;R. Snyders
中科院分区：
文献类型：
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作者：
Pierre-Antoine Cormier;R. Snyders
Cu2ZnSnS4(CZTS)适用于替代传统材料作为太阳能电池的吸收层。CZTS由地球上丰富的无毒元素组成，在可见光范围内具有1.5 eV的光学带隙和高吸收系数。CZTS薄膜的制备通常采用“两步法”，即沉积金属前驱体(铜、锌和锡)，然后在含硫气氛中进行热处理。这些技术可以开发高效的太阳能电池，但存在主要缺点：(I)对薄膜性能的控制较低，以及(Ii)与大规模应用的两步工艺实施有关的问题。在这项工作中，我们提出了一种“一步法”，即在Ar/H_2S混合气体中反应磁控共溅射两种金属靶(铜-锡合金和锌)，成功地合成了晶化的CZTS。多波长拉曼光谱(325、532和785 nm)证明了在特定条件下CZTS的存在。我们的数据表明，生长晶化的CZTS薄膜需要高于300℃的衬底温度，并且晶体结构取决于施加到CuSn靶(PCuSn)上的功率。对于低PcuSn值，获得了低含量的−薄膜(贫铜和富S的化学计量比)。随着PCuSn量的增加，CZTS逐渐失去了SnS、Cu4Zn团簇和ZnS的优势，这是由于高的铜浓度和低的S浓度共同作用的结果。最后，最有希望用于光伏应用的薄膜具有致密的微结构，具有大的(200-300 nm)CZTS颗粒。
Cu2ZnSnS4(CZTS) is suitable to replace conventional materials as absorber layer in solar cell applications. CZTS is composed of earth abundant and non-toxic elements, and exhibits an optical bandgap of 1.5 eV and a high absorption coefficient in the visible range. CZTS thin films are usually synthesized by “two-step” processes consisting on the deposition of metallic precursors (Cu, Zn and Sn) followed by an annealing in sulfur containing atmosphere. These techniques allow developing efficient solar cells, but present major drawbacks: (i) a low control of the film properties, and (ii) the problems related to the implementation of a two steps process for large scale applications. In this work, we present the successful synthesis of crystallized CZTS using a “one-step” process namely the reactive magnetron co-sputtering of two metallic targets (copper–tin alloy and zinc) in Ar/H2S mixture. Multiwavelength Raman spectroscopy (325, 532 and 785 nm) demonstrated the presence of CZTS for specific conditions. Our data reveal that a substrate temperature higher than 300 °C is required to grow crystallized CZTS films and that the crystalline structure depends on the power applied to the CuSn target (PCuSn). For lowPCuSn, CZTS films containing low concentrations of ZnS and Cu2−xS are obtained (Cu poor and S rich stoichiometry). IncreasingPCuSn, CZTS disappears to the profit of SnS, Cu4Zn clusters and ZnS which is explained by the combination of high Cu concentration and low S concentration. Finally, the most promising film for photovoltaic applications exhibits a dense microstructure with large (200–300 nm) CZTS grains.