| 초록 |
A photoelectrochemical (PEC) water splitting has been intensively investigated as it offers an eco-friendly way to generate hydrogen fuels from water at the semiconductor/electrolyte interface. Recently, copper based chalcopyrites such as Cu(In,Ga)Se2 (CIGS), CuInS2, CuGaSe2, and Cu2ZnSnS4 have been receiving a great attention as a light absorbing semiconductor in PEC cells due to their great absorption capabilities, low band-gap (＜ 2.0 eV), hence being able to absorb a great portion of the solar spectrum, and tunability of the band structure through composition engineering. Especially, CIGS is the most promising candidate based on its great success in solar cell applications. During PEC reaction, however, CIGS suffers from the decomposition of copper atoms from the surface, because the reduction potential of copper is negatively positioned compared to the standard hydrogen reduction potential. Therefore, protective strategies have to be considered for stable operation of the PEC cells for long time. We investigated application of metal chalcogenide and/or transition metal oxide on p-type CIGS that protects the CIGS surface as well as modifies the band structure of CIGS to facilitate the separation of photo-generated carriers. The effect of different protective layers on PEC reaction and the stability of the PEC cells will be discussed.
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