Thin-film materials for space power applications

This chapter is focused upon use of the three major families of thin-film solar cell (TFSC) materials for space applications: amorphous silicon (a-Si), cadmium telluride (CdTe), and copper indium gallium selenide (CIGS). Clearly, there are distinct advantages to be realized through use of thin III-V and perovskite hybrid materials for photovoltaics (PV) for space power generation. However, studies of inorganic TFSC materials have yielded several potential space applications as well as numerous scientific and technological insights over the past 50 years. A short discussion of the difference between space (air mass zero, AM0) and terrestrial (AM1.0 or AM1.5) solar radiation begins the chapter. After contrasting crystalline and TFSCs, we explore the key components of TFSC devices; performance and technical challenges of the main inorganic absorber materials are then considered. We examine, in context, several unique stressors in the space environment, varying with location, that challenge TFSC devices. Thermal issues in space, including cycling and thermal load, are more extreme than those encountered by terrestrial installations; other issues include atomic oxygen and various types of radiation (alpha, beta, gamma, and cosmic rays). Device structure(s), including mass specific power and processing details, as well as testing relevant to use of TFSCs for space missions are examined. A brief summary of past, present, and future applications for space exploration concludes the chapter. Finally, we highlight several examples of technology transfer to other PV devices and related technologies.