Microcrystalline silicon oxide (μc-SiOx:H) alloys: A versatile material for application in thin film silicon single and tandem junction solar cells

We report on the development and application of n-type hydrogenated microcrystalline silicon oxide (mu c-SiOx:H) alloys in single and tandem junction thin film silicon solar cells. Single junction microcrystalline silicon (mu c-Si:H) solar cells are prepared in n-i-p deposition sequence where n-type mu c-SiOx:H films serve as window layers. In tandem solar cells, mu c-SiOx:H layers are placed between amorphous (a-Si:H) and mu c-Si:H component cells, serving as an intermediate reflector. The requirements for mu c-SiOx:H layer depending on its application are discussed. Our results show that the optical, electrical and structural properties of mu c-SiOx:H can be conveniently tuned over a wide range to fulfil various requirements for applications in both types of cells. Additionally, the properties of mu c-SiOx:H layers appear to be substrate dependent, which should be taken into account when layers are utilized in cells. The advantages of low refractive index and high optical band gap allow to achieve high efficiencies of 9.2% and 12.6% for single junction and tandem solar cells, respectively. (C) 2011 Elsevier B.V. All rights reserved.