Sol gel prepared sodium alumino-silicate coatings on flexible stainless steel substrates

• Main Authors: Hsing-SingYin, 因信興
• Other Authors: Jyh-Ming Ting
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/80726501512518414095

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 100 === As stainless steel is applied to flexible substrates of CIS/CIGS solar cells, the factors of electrical conductivity, rough surface, contamination of iron, and the deficiency of sodium lead to the reduction of the efficiency and performance of solar cells and modules. Therefore, deposition of barrier layer is required. Here, we tried another material: sodium alumino-silicate to apply to barrier layer and sodium source. In this study, we prepared aluminum silicate and sodium alumino -silicate by sol-gel method which possesses characters of simple, high throughput and good homogeneity for preparing the coatings. Here, we prepared sol with various molar ratios of Al/SiAl/Si = 0, 0.1, 0.2 and Na/Si = 0, 0.1, 0.2, and spin-coated on SUS 304 stainless steel with 100℃ for 0.5 hr and 500℃ for 2 hrs heat-treatment for densification. In first part, the integrity, morphology, and sheet resistance were investigated by microscopy (OM, SEM, and AFM) and four point probe, respectively. The results show that modification of condensation rate of precursors by addition of Al3+ makes coating avoid from seriously delaminating and cracking during the heat-treatment. By SEM and AFM as well as XRD, both coatings with or without sodium-contained show smooth, transparent, and homogeneous, and appear amorphous. By four point probe, the sheet resistance of coating attains more than 200MΩ/□. In second part, we analyzed its composition, bonding structure, and distribution of elements via ATR-IR and XPS. Aluminum silicate coatings show good capability of diffusion barrier and homogeneity in composition. However, as the addition of sodium, capability of diffusion barrier is reduced. Regardless of single (SA2N) or double layer (SA3N/SA2) coatings or annealing, sodium always localized at the interface between coating and substrate. Via spectra of ATR-IR and O 1s, the distribution of sodium may be influenced by the existence of hydroxyl bonds in matrix and NBO at interface. At last, CuInS2 and Mo were deposited on SLG and SA2/SS. Absorber layer on SA2/SS still peeled off the substrates. Observed by SEM, XRD, and Raman, we can find that morphology of CuInS2 is different from the substrates, but crystal structure of CuInS2 is almost the same. In XPS depth profile, it shows that elements in precursor layer diffused toward the substrate which leads to the variation of morphology.