Improving efficiencies of Cu2ZnSnS4 nanoparticle based solar cells on flexible glass substrates
Improving efficiencies of Cu2ZnSnS4 nanoparticle based solar cells on flexible glass substrates
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DOI：
10.1016/j.tsf.2017.09.009
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发表时间：
2017-11-30
期刊：
影响因子：
2.1
通讯作者：
Agrawal, Rakesh
中科院分区：
文献类型：
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作者：
Brew, Kevin W.;McLeod, Steven M.;Agrawal, Rakesh
尽管其机械结构不灵活，毫米厚的钠钙玻璃通常用于制造 Cu2ZnSn(S,Se)(4) (CZTSSe) 薄膜太阳能电池；由于本征钠掺杂而改善了硫族化物吸收层的烧结以及随后更高的器件效率，使得钠钙玻璃成为首选基板。薄且柔性的 Corning (R) Willow (R) 玻璃在柔性太阳能电池的无污染制造方面具有独特的优势，因为它可以在高性能薄膜太阳能电池所需的高温（约 500 摄氏度至 550 摄氏度）下进行加工。在这项研究中，我们报告了使用 Cu2ZnSnS4 (CZTS) 纳米粒子墨水在柔性玻璃基板上成功进行实验室规模制造的 CZTSSe 太阳能电池，并确定了必要的工艺变化，以将器件性能与钠钙玻璃 (SLG) 制造的标准器件相结合。由于 Willow 玻璃中的钠浓度小到可以忽略不计，因此探索了在硒化过程中向吸收膜供应钠的情况。研究发现，在硒化之前将涂覆的 CZTS 薄膜浸泡在氯化钠中会对功率转换效率 (PCE) 产生不利影响。或者，在硒化之前在 CZTS 纳米粒子薄膜顶部掺杂一层 NaF 薄膜，可以略微改善器件性能。添加 10 nm 厚的 NaF 层将平均器件效率从 6.2 +/- 0.3% 略微提高到 6.4 +/- 0.4%，并且基于总电池面积的 PCE 达到创纪录的 6.9%。钠掺杂导致更高的 V-oc 导致效率提高。虽然这些初步结果证明了 Willow Glass 作为纳米颗粒光伏器件灵活支撑的潜力，但仍需要继续开发改进的加工方法以进一步提高 PCE 值。
In spite of its mechanically inflexible structure, millimeter thick soda-lime glass is generally used for fabrication of Cu2ZnSn(S,Se)(4) (CZTSSe) thin film solar cells; improvements in sintering of the chalcogenide absorber layer from intrinsic sodium doping and subsequent higher device efficiency make soda-lime glass the preferred substrate. Thin and flexible Corning (R) Willow (R) Glass provides a unique advantage in contaminant-free fabrication of flexible solar cells, as it can be processed at the elevated temperatures (c.a. 500 degrees C-550 degrees C) needed for high performance thin film solar cells. In this study, we report successful lab-scale fabrication of CZTSSe solar cells on flexible glass substrates from nanoparticle inks of Cu2ZnSnS4 (CZTS), and identify necessary process changes to bridge device performance to standard devices fabricated with soda-lime glass (SLG).Since the sodium concentration in Willow Glass is negligibly small, supply of sodium to the absorber film during selenization was explored. Soaking coated CZTS films in sodium chloride prior to selenization was found to have a detrimental effect on power conversion efficiency (PCE). Alternatively, sodium doping with a thin NaF film on top of the CZTS nanoparticles films prior to selenization resulted in slightly improved device performance. The addition of a 10 nm thick NaF layer slightly increased the average device efficiency from 6.2 +/- 0.3% to 6.4 +/- 0.4% with a record 6.9% PCE based on total cell area. The increased efficiency results from higher V-oc due to the sodium doping. While these initial results demonstrate the potential of Willow Glass as a flexible support for nanoparticle based photovoltaic devices, there is a need to continue developing improved processing methods to further enhance PCE values.