Advanced CIGS Photovoltaic Technology: Annual Technical Report, 15 November 2001-14 November 2002

Energy Photovoltaics, Inc. (EPV) has consistently pursued a vacuum-based approach to CIGS production, using novel linear-source technology and standard soda-lime glass substrates. It has also chosen to develop processing methods with worker safety in mind. These choices result in layers having controllable purity and low physical defects, and production without significant hazards. Considerationssuch as these are important in helping to minimize the processing costs of CIGS. Technically, thin-film PV technologies have advanced considerably in the last few years. EPV successfully produced high-quality 0.43m2 Mo-coated glass substrates that, when cut, enabled NREL to produce 17.1% CIGS cells on such substrates. EPV successfully used novel linear evaporative sources for supply of Cu, In,Ga, and Se to form CIGS on 0.43m2 substrates, producing modules with Voc's of up to 37 V. A new approach to buffer-layer deposition was pioneered through synthesis of the compound ZnIn2Se4 and its use as a source material. In addition, the current generated in exploratory a-Si/a-Si/CIGS stacked devices was increased from 6 to 13 mA/cm2. Supporting these programs, EPV's upgraded analyticallaboratories provided rapid in-house feedback concerning material and device properties. The objective of this subcontract is to develop and assemble the various pieces of new technology that EPV considers essential for cost-effective production of CIGS modules. The long-term objective of the Thin Film PV Partnership Program is to demonstrate low-cost, reproducible modules of 15% aperture-areaefficiency.