Photovoltaic Technologies at IEC

Since its inception in 1972, IEC has taken the lead in the development of thin-film photovoltaic cells and the education of students and professionals with expertise in photovoltaic research, development and design. Central to the Institute's research today is the design, fabrication and analysis of solar cells made from the following inexpensive thin-film semiconductor materials:

• cadmium telluride
• copper indium diselenide
• amorphous silicon
• thin Si on low cost substrates

IEC has made the materials and devices necessary to evaluate these thin-film cells at the laboratory scale. Solar cells with conversion efficiencies of over ten percent have been achieved with all of these materials at IEC. In its effort to help the photovoltaic community to achieve commercially viable solar modules, IEC has concentrated on developing, implementing, and analyzing laboratory experiments which provide essential information for the manufacture of large-area photovoltaic modules. To do this effectively, the Institute's multi-disciplinary team of physicists, material scientists and electrical and chemical engineers work together in an integrated approach encompassing: Materials Synthesis The materials research program at IEC has made thin-film photovoltaic devices from the following materials.

• copper sulfide and copper-silver sulfide alloys
• cadmium sulfide and cadmium-zinc sulfide alloys
• zinc phosphide
• iron sulfide
• amorphous silicon and amorphous silicon-germanium alloys
• copper indium diselenide and copper indium-gallium diselenide alloys
• cadmium telluride and cadmium-mercury telluride alloys

Process Equipment Design and Operation

Recent research in this area includes the following:

• IEC developed two different laboratory scale reactors to form copper indium diselenide films by selenizing copper indium layers using either elemental selenium or hydrogen selenide.
• IEC conducted award-winning quantitative reaction and reactor analysis of chemical vapor deposition and physical vapor deposition reactors which has provided a basis for commercial scale reactor design.
• IEC developed a reproducible and controllable three effusion source system for depositing copper indium diselenide films.
• IEC created and patented a novel photochemical vapor deposition reactor that made the material for state-of-the-art amorphous silicon solar cells.

Device Design and Analysis

IEC believes that it is essential to build functioning devices, i.e., solar cells, to test its material fabrication procedure and to provide feedback for the design and operation of the reactors. IEC operates an extensive cell testing facility for the optical and electrical testing of materials and devices.