Transparent conductors for thin film solar cells

薄膜光伏面板、智能手机和触摸屏电视显示器等设备依靠薄膜透明导电氧化物(TCO)进行电接触。透明导体通常沉积在内部玻璃表面上，并通过封装在器件内进行保护。然而，在一些太阳能电池应用中，它是暴露在环境中的薄膜堆叠的一部分。在这两种情况下，TCO随着时间的推移保持其性能非常重要。TCO的性能由其光学、电学和结构属性决定。太阳能应用中最重要的TCO是铟锡氧化物(ITO)、掺铝氧化锌(AZO)和掺铟氧化锌(IZO)。利用组合溅射技术，将制备一系列ITO组合物，并绘制它们的光学和电学性质图。这些特性将与太阳能应用的要求相匹配。一种应用是一种涂层，它在可见光波长下是抗反射的，但在红外线中是反射的。反射红外线有助于保持模块的凉爽，提高效率和模块可靠性。折射率、色散和吸收是关键的性能参数。另一个潜在的重要应用是开发双表面薄膜太阳能电池，其中方阻和载流子浓度的电学特性很重要。透明导体暴露在大气中时的稳定性尚未确定。该项目将结合实验室环境压力测试和实际室外暴露测试来确定是否发生降解。实验室测试将包括湿热(85摄氏度，85%湿度)、紫外线照射、温度循环、湿度冻结等。除了方块电阻的电学测试外，还将使用扫描电子显微镜(SEM)和X射线光电子能谱(XPS)研究涂层的化学和结构降解。

Devices such as thin film photovoltaic panels, smartphones and touch screen television displays rely on a thin film transparent conducting oxide (TCO) to make electrical contact. The transparent conductor is usually deposited on the inside glass face and is protected by being encapsulated within the device. However, in some solar cell applications it is part of a thin film stack that is exposed to the environment. In both cases, it is important that the TCO retains its performance over time.The performance of a TCO is determined by its optical, electrical and structural properties. The most important TCO's for solar applications are Indium Tin Oxide (ITO), Aluminium doped Zinc Oxide (AZO) and Indium doped Zinc Oxide (IZO). Using combinatorial sputtering a range of ITO compositions will be fabricated and mapped for their optical and electrical properties. These properties will be matched to the requirements of solar applications. One application is a coating that is anti-reflecting in the visible wavelengths but reflecting in the infra-red. Reflecting the infra-red helps to keep the module cool, improving efficiency and module reliability. The refractive index dispersion and absorption are the key performance parameters. Another potentially important application is the development of a bifacial thin film solar cell where the electrical properties of sheet resistance and carrier concentration are important.The stability of transparent conductors when exposed to the atmosphere has not been established. This project will use a combination of Laboratory environmental stress tests and real outdoor exposure tests to determine if degradation occurs. The Laboratory tests will include damp heat (85C, 85% humidity), UV exposure, temperature cycling, humidity freeze etc. In addition to electrical tests of sheet resistance, the chemical and structural coating degradation will be investigated using Scanning Electron Microscopy (SEM) and X-ray photoelectron spectroscopy (XPS).