Antireflective coatings on solar glass

In order to minimize efficiency losses due to reflection of sun light on the front glass of PV modules, high-end solar glass is often equipped with an antireflective coating. The coating is deposited as a liquid by spray-coating or by printing techniques. Thereafter it is dried and annealed in consecutive production steps. The properties of the coating must be optimized in a way that the minimum of the reflectance matches the spectral absorption and conversion efficiency of the solar cells. Hence, spectral reflectance measurements directly deliver the most relevant information to characterize the coating in the production line. Fig. 1 shows the reflectance of uncoated glass and of glass coated by two different ARCs.
Reflectance spectra of uncoated glass and of AR coated glass with reflection minima at 665 nm and 760 nm.
Fig. 1. Reflectance spectra of uncoated glass and of AR coated glass with reflection minima at 665 nm and 760 nm.

As the reflectance of an ARC on glass is very low (this is the very purpose of the ARC) and it is mostly deposited on rolled glass which is used in this field of application, in-line measurements are quite challenging. However, optimisation of the optical metrology system’s design allows measurements with a repetition rate of up to 100 Hz even under these conditions.

Download the poster "Optical in-line monitoring of deposited layers in large area coating lines" (presented at ICCG-11)









应用:在集群系统完成沉积后,生产线反射率测量可直接对非晶硅/SiO/SiN层叠的即时层进行厚度分析,其第8代玻璃面板上具有金属接触图案。 ###HIDE###系统不会对单件工时造成影响,可以便捷的集成于传送带生产线上。每个面板在各跟踪范围内可设置100个测量点。可以对整个面板尺寸进行同质化的控制和统计分析(最小值、最大值、平均值、百分比)。




Fig. 1+2: a-Si thickness on two substrates A and B: in-line Flames is compared to ex-situ reference (Horiba)                                                                                                                                             

  • 由于折射指数较小,因此在使用其他参考椭圆仪测量非晶硅层时,得出的厚度值较大。两种测量方式均可解决厚度波动问题。可在全部衬底的即时层和覆盖层进行Flames在线测量,而其他参考方法需要耗时几分钟,仅适用于少数衬底。



有关Flames系统优化制程的详细信息,请联系mail@laytec.de或拨打电话+49(0)30 89 00 55-0。

CdTe and CIGS based thin-film PV

Combining two Flames metrology systems of different spectral range gives access to measuring the properties and thickness of all layers throughout thin-film solar cell manufacturing processes, including transparent conducting oxide (TCO) and absorber and buffer layers. Especially, with the IR spectral range included, the position and number of interference fringes of the thick absorber layers can be automatically analyzed and fitted to determine the absorber’s film thickness on-line. By measuring the reflectance after each deposition step, the thickness of each layer can be determined with high precision.

While TCO and CdS film thicknesses are detected with a spectrometer operating in the visible to near-infrared spectral range (500–1000 nm), a determination of the film thickness of the absorber layer requires an infrared reflectance measurement, as these materials are designed to completely absorb visible light. The thickness measurement accuracy is typically 1–2 %. LayTec has built upon its extensive expertise in fitting optical data and accurately measuring optical properties (n and k values) in multi-layer processes to create the most precise automated thickness analysis available for thin-film PV.

To find out how Flames can optimize your process please contact mail@laytec.de or simply call +49(0)30 89 00 55-0.