SBIR Phase II: Fabrication of Low-bandgap Nano-crystalline SiGeC Thin Films Using the Plasma Enhanced Chemical Vapor Deposition (PECVD) Technique

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。SBIR二期项目是开发薄膜串联太阳能电池，由纳米晶硅和硅碳（nc-Si和nc-Si:C）吸收材料组成，转换效率约为20%。一期项目成功研制出关键元件之一，即具有~ 1.5 eV禁带隙（Eg）和良好光电性能的本征nc-Si:C。这种关键材料最初将在第二阶段用于制造单结配置的电池，效率目标为~10%。此前，开发的“器件级”纳米硅材料（Eg ~1.1eV）被用于生产效率~8%的太阳能电池。将两个器件集成在串联结结构中，预计将产生约18%的效率。通过在p/i或i/n接口处使用缓冲层，并通过增加晶粒尺寸来提高开路电压Voc，可以进一步提高串联结器件的效率，达到~20%。高效率的薄膜串联太阳能电池将是实现广泛采用光伏发电系统所必需的低成本的关键。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This SBIR Phase II project is to develop thin film tandem solar cells, comprising of nanocrystalline silicon and silicon carbon (nc-Si and nc-Si:C) absorber materials, with a conversion efficiency of ~20%. The phase I project successfully developed one of the key components, i.e. intrinsic nc-Si:C with a band gap, Eg, of ~ 1.5 eV and with good opto-electronic properties. This key material will be used initially in phase II to fabricate cells in a single junction configuration with an efficiency goal of ~10%. Previously, developed "device quality" nc-Si materials, with Eg ~1.1eV, were used to produce solar cells with efficiency ~8%. Integrating the two devices in a tandem junction configuration is forecast to yield efficiencies of ~18%. Further improvement in the tandem junction device efficiency,to ~20%, may be achieved via the use of buffer layers at the p/i or i/n interfaces and by increasing the grain size which would boost the open circuit voltage, Voc.Higher efficiency thin film tandem solar cells will be critical to achieving the low costs necessary to achieve widespread adoption of photovoltaic energy generating systems.