EAGER: Tandem solar cells of two dissimilar material systems

北卡罗莱纳州立大学bedair， s.m.b eager：两种不同材料系统的串联太阳能电池摘要串联太阳能电池是一种能够实现转换效率高于45%的方法。这种方法包括堆叠几个具有不同性质的电池，以最佳地利用太阳光谱。目前，所有的卫星和空间通信系统都是由串联太阳能电池结构供电的。然而，这些结构受到一些限制，如成本和材料相关问题。因此，它们无法竞争目前由硅和效率低于20%的廉价电池技术主导的地面应用。这个EAGER项目的目标是发展科学技术，使高效串联电池概念应用于由廉价材料系统制成的电池。我们提出了一种新的方法，依靠金属间键（IMB）将两个或多个可能由不同材料系统组成的电池组装成串联电池结构。这种IMB方法可以影响几个不同的领域，例如在不同波长发射的led和双波长光电探测器。参与该项目的研究生和本科生将获得器件制造，测试和建模的经验。学生将参与影响国家可再生能源目标的研究活动。IMB方法依赖于铟（In）金属的粘附特性。铟薄膜将被沉积在现有的各种太阳能电池的网格接触上。通过在室温下施加压力，两个电池之间形成金属键合，从而实现电池之间的键合。研究计划将集中于IMB技术的发展，调整顶部电池的底部接触和底部电池的顶部接触，找到机械强度和低电阻连接结的最佳条件，并将遮蔽损失降到最低。我们将从现成的底部电池[Si （1.1 eV）或CIGS (1.0 eV)]和PI实验室的外延生长结中研究MJ结构，用于基于InGaP/多量子阱结构或AlGaAs的顶部电池，以调节带隙在1.55至1.7 eV之间。在双终端设备结构中，上述组合可以接近接近30%的效率。我们已经成功地将IMB技术应用于GaAs/InGaP和Si/GaAs的结合，显示出机械稳定性和导电性。我们已经证明，IMB提供了非常低电阻率的互连，并成功地应用于GaAs/Si串联电池的概念验证。

ECCS-1665211Bedair, S. M.North Carolina State UniversityEAGER: Tandem Solar Cells of Two Dissimilar Material SystemsABSTRACTTandem solar cells are an approach capable of achieving a conversion efficiency higher than 45%. This approach involves stacking several cells with different properties for the optimum utilization of the solar spectrum. Currently all satellite and space communication systems are powered by tandem solar cell structures. However these structures suffer from several limitations such as cost and material related issues. They thus cannot compete for terrestrial applications which are currently dominated by silicon and inexpensive cell technology with efficiencies less than 20%. The goal of this EAGER project is to develop the science and technology to allow the high efficiency tandem cell concept to be applied to cells made from inexpensive material systems. We propose a new approach that relies on intermetallic bonding (IMB) to assemble two or more cells that may be composed of dissimilar material systems into a tandem cell structure. This IMB approach can impact several different fields such as LEDs emitting at different wavelengths and dual wavelength photodetectors. Graduate and undergraduate students involved in this project will gain experience in device fabrication, testing and modeling. Students will be part of research activities that can impact the national goals of renewable energy.The IMB approach relies on the adhesion properties of indium (In) metal. Indium films will be deposited on the existing grid contacts of various solar cells. Bonding between the cells will take place by applying pressure at room temperature, resulting in In-metal bonding between the two cells. The research program will focus on the development of the IMB technique, aligning the bottom contact of the top cell and top contact of the bottom cells, finding the optimum conditions for both mechanical strength and a low resistance connecting junction with minimum shadowing losses. We will investigate MJ structures from off-the-shelf bottom cells [Si (1.1 eV) or CIGS (1.0 eV)] and epitaxially grown junctions from the PI's lab for the top cell based on InGaP/multiple quantum well structures or AlGaAs to tune the band gap between 1.55 and 1.7 eV. The above combinations can approach efficiencies close to 30%, in a two terminal device structure. We have successfully applied the IMB technique to bond GaAs/InGaP and Si/GaAs showing both mechanical stability and electrical conductivity. We have shown that the IMB offers a very low resistivity interconnects and was successfully applied to demonstrate the proof of concept in the case of GaAs/Si tandem cell.