TY - JOUR
T1 - Unraveling interface characteristics of Zn(O,S)/Cu(In,Ga)Se2 at nanoscale
T2 - Enhanced hole transport by tuning band offsets
AU - Kim, Juran
AU - Kim, Jayeong
AU - Ko, Eunji
AU - Park, Ha Kyung
AU - Yoon, Seokhyun
AU - Cho, Dae Hyung
AU - Lee, Woo Jung
AU - Chung, Yong Duck
AU - Jo, William
N1 - Funding Information:
This research was supported by the Technology Development Program to Solve Climate Changes of the National Research Foundation (NRF) of Korea ( 2016M1A2A2936784 and 2016M1A2A2936754 ), the DGIST R&D Program (19-BD-05) funded by the Ministry of Science, ICT & Future Planning, Republic of Korea , and the Basic Science Research Program ( 2018R1A6A1A03025340 ) of the NRF of Korea funded by the Ministry of Education.
Publisher Copyright:
© 2019
PY - 2020/4/15
Y1 - 2020/4/15
N2 - Environment-friendly Cu(In,Ga)Se2 (CIGS) solar cells requires the replacement of Cd-containing buffers with non-toxic materials. Zn(O,S) buffers have been developed and yielded even better efficiency than CdS-buffered CIGS thin-film solar cells [23.35%, Ref. [6]]. In this work, we studied band offsets of Zn(O,S) and CIGS interfaces. The Cd-free buffer layers were deposited with 1.0%, 1.3%, and 1.6% oxygen (O2) gas partial pressure during the deposition. Effects of the oxygen partial pressure on the structure and electronic properties of the devices were investigated by micro-Raman scattering spectroscopy and Kelvin probe force microscopy, respectively. We achieved depth-profiling of spatial work function mapping across the interface between the absorbers and the buffers. The best efficiency sample, grown using 1.3% of oxygen, showed 80 mV spike-like band offsets. We propose that the efficiency can be improved through tailoring of the band offsets at the interface as well as improving the absorber and the buffer materials.
AB - Environment-friendly Cu(In,Ga)Se2 (CIGS) solar cells requires the replacement of Cd-containing buffers with non-toxic materials. Zn(O,S) buffers have been developed and yielded even better efficiency than CdS-buffered CIGS thin-film solar cells [23.35%, Ref. [6]]. In this work, we studied band offsets of Zn(O,S) and CIGS interfaces. The Cd-free buffer layers were deposited with 1.0%, 1.3%, and 1.6% oxygen (O2) gas partial pressure during the deposition. Effects of the oxygen partial pressure on the structure and electronic properties of the devices were investigated by micro-Raman scattering spectroscopy and Kelvin probe force microscopy, respectively. We achieved depth-profiling of spatial work function mapping across the interface between the absorbers and the buffers. The best efficiency sample, grown using 1.3% of oxygen, showed 80 mV spike-like band offsets. We propose that the efficiency can be improved through tailoring of the band offsets at the interface as well as improving the absorber and the buffer materials.
KW - Cu(In
KW - Ga)Se thin-film solar cells
KW - Kelvin probe force microscopy (KPFM)
KW - Micro-Raman scattering spectroscopy
KW - Zn(O,S) buffer layer
UR - http://www.scopus.com/inward/record.url?scp=85076826212&partnerID=8YFLogxK
U2 - 10.1016/j.apsusc.2019.144782
DO - 10.1016/j.apsusc.2019.144782
M3 - Article
AN - SCOPUS:85076826212
SN - 0169-4332
VL - 509
JO - Applied Surface Science
JF - Applied Surface Science
M1 - 144782
ER -