Toward Understanding Chalcopyrite Solar Cells via Advanced Characterization Techniques

In response to global environmental concerns, the importance of renewable energy, especially photovoltaic technology, is widely emphasized. As such, various efforts are made to improve the efficiency of solar cells, leading to significant technological advances supported by effective analysis and characterization techniques. Understanding these characterization techniques is important when looking to overcome technological limits and set the direction of technological development. Because the electrical properties of device, such as the carrier lifetime, doping density, energy levels, and surface potential, are generally determined based on the crystallographic phase, morphology, and compositional distribution, characterization techniques are developed to provide quantitative information on the absorber, surface, and interfaces of solar cells in order to improve their overall performance. In this review, basic to advanced characterization techniques for chalcopyrite solar cells are introduced. Because chalcopyrite solar cells exhibit high efficiency and are already commercialized, this can be a good lesson for studying the technological development history regarding efficiency improvement with characterization of thin-film solar cells. Based on the various characterization techniques reviewed in this paper, structure−property relationships are established, thus providing a foundation for the development of strategies to improve processing conditions and thus increase the efficiency of solar cells.