TY - JOUR
T1 - Control of Structural and Electrical Properties of Indium Tin Oxide (ITO)/Cu(In,Ga)Se 2 Interface for Transparent Back-Contact Applications
AU - Son, Yu Seung
AU - Yu, Hyeonggeun
AU - Park, Jong Keuk
AU - Kim, Won Mok
AU - Ahn, Seung Yeop
AU - Choi, Wonjun
AU - Kim, Donghwan
AU - Jeong, Jeung Hyun
N1 - Funding Information:
This work was supported by the internal program of Korea Institute of Science and Technology (KIST), by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) (Nos. 20153030013060, 20158520000060), and by the Technology Development Program to Solve Climate Changes of the National Research Foundation (NRF) funded by the Ministry of Science, ICT & Future Planning (No. 2016M1A2A2936782) of Republic of Korea.
PY - 2019/1/24
Y1 - 2019/1/24
N2 - Development of transparent-conducting oxide (TCO) back contact for Cu(In,Ga)Se 2 (CIGS) absorber is crucial for bifacial CIGS photovoltaics. However, inherent GaO x formation at the TCO/CIGS interface has hampered the photocarrier extraction. Here, by controlling the Na doping scheme, we show that the hole transporting properties at the indium-tin oxide (ITO)/CIGS back contact can be substantially improved, regardless of the GaO x formation. Na incorporation from the glass substrate during the GaO x forming phase created defective states at the interface, which allowed efficient hole extraction from CIGS, while post Na treatment after GaO x formation did not play such a role. Furthermore, we discovered that an almost GaO x -free interface could be made by reducing the underlying ITO film thickness, which revealed that ITO/CIGS junction is inherently Schottky. In the GaO x -free condition, post-Na treatment could eliminate the Schottky barrier and create ohmic junction due to generation of conducting paths at the interface, which is supported by our photoluminescence analysis.
AB - Development of transparent-conducting oxide (TCO) back contact for Cu(In,Ga)Se 2 (CIGS) absorber is crucial for bifacial CIGS photovoltaics. However, inherent GaO x formation at the TCO/CIGS interface has hampered the photocarrier extraction. Here, by controlling the Na doping scheme, we show that the hole transporting properties at the indium-tin oxide (ITO)/CIGS back contact can be substantially improved, regardless of the GaO x formation. Na incorporation from the glass substrate during the GaO x forming phase created defective states at the interface, which allowed efficient hole extraction from CIGS, while post Na treatment after GaO x formation did not play such a role. Furthermore, we discovered that an almost GaO x -free interface could be made by reducing the underlying ITO film thickness, which revealed that ITO/CIGS junction is inherently Schottky. In the GaO x -free condition, post-Na treatment could eliminate the Schottky barrier and create ohmic junction due to generation of conducting paths at the interface, which is supported by our photoluminescence analysis.
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U2 - 10.1021/acs.jpcc.8b11149
DO - 10.1021/acs.jpcc.8b11149
M3 - Article
AN - SCOPUS:85060023085
VL - 123
SP - 1635
EP - 1644
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
SN - 1932-7447
IS - 3
ER -