Prof Byung Tae AHN

Prof Byung Tae AHN

Korea Advanced Institute of Science and Technology (KAIST), South Korea

Control of point defects in CIGS films and their effect on the CIGS cell performance

The electrical properties of CIGS film are critically affected by the bulk point defects in addition to interfacial defects. Especially the donor-type point defects such as Se vacancy and antisite defect should be well suppressed. We found that those defects can be reduced by simple Se annealing at 300°C. As a result, the short-circuit current of the CIGS solar cell clearly increased, while the fill factor and open-circuit voltage were degraded. With an appropriate surface treatment of the CIGS film in addition to Se annealing, the fill factor and open-circuit voltage of CIGS cells also increased significantly in addition to the short-circuit current. We will report examples of defect control in α-CIGS and β-CIGS films. The origin of the cell performance enhancement was described by analyzing the low temperature photoluminescence, x-ray photoelectron spectroscopy, the reverse saturation current from diode curves, and the carrier lifetimes from time-resolved photoluminescence.


Professor Byung Tae Ahn obtained Ph.D. in Materials Science and Engineering from the Stanford University in 1988. He worked for ETRI, Samsung Electronics, and IBM. He became a professor in the Department of Materials Science at KAIST in 1992. He has been actively working on the thin-film solar cells including CdTe and CIGS since 1992. He continuously participated PVSEC Meetings and became one of IAC members of the PVSEC in 2002. He served PVSEC-12 (2001), 19 (2009), and 25 (2015) as General Secretary, Program Chair, and General Chair, respectively. He is the editor-in-chief of ‘Current Photovoltaic Research’, a quarterly PV journal published by Korea PV Society. He was the president of MRS-Korea and is the vice president of Korea Photovoltaic Society. He was the Head of the Department of Materials Science and Engineering at KAIST and the director of ‘Center for Inorganic Photovoltaic Materials’ funded by Korean government.