1. Department
of Materials Science and Engineering, Korea University, Seongbuk-gu,
Anam-dong, 136-713 Seoul, Korea
2. Department
of Solar Cells - Development and Characterization, Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstr. 2, 79110 Freiburg, Germany
3. KU•KIST
Green School, Graduate School of Energy and Environment, Korea University, Seongbuk gu, Anam dong, 136-713 Seoul, Korea