@article{31bd96fbb338466a99b1b5dddfdd90d5,
title = "Morphological–Electrical Property Relation in Cu(In,Ga)(S,Se)2 Solar Cells: Significance of Crystal Grain Growth and Band Grading by Potassium Treatment",
abstract = "Solution-processed Cu(In,Ga)(S,Se)2 (CIGS) has a great potential for the production of large-area photovoltaic devices at low cost. However, CIGS solar cells processed from solution exhibit relatively lower performance compared to vacuum-processed devices because of a lack of proper composition distribution, which is mainly instigated by the limited Se uptake during chalcogenization. In this work, a unique potassium treatment method is utilized to improve the selenium uptake judiciously, enhancing grain sizes and forming a wider bandgap minimum region. Careful engineering of the bandgap grading structure also results in an enlarged space charge region, which is favorable for electron–hole separation and efficient charge carrier collection. Besides, this device processing approach has led to a linearly increasing electron diffusion length and carrier lifetime with increasing the grain size of the CIGS film, which is a critical achievement for enhancing photocurrent yield. Overall, 15% of power conversion efficiency is achieved in solar cells processed from environmentally benign solutions. This approach offers critical insights for precise device design and processing rules for solution-processed CIGS solar cells.",
keywords = "CIGS solar cell, average domain spacing, band grading, electron diffusion length, solution process",
author = "Kim, {Joo Hyun} and Kim, {Min Kyu} and Abay Gadisa and Stuard, {Samuel J.} and Nahid, {Masrur Morshed} and Soyeong Kwon and Soohyun Bae and Byoungwoo Kim and Park, {Gi Soon} and Won, {Da Hye} and Lee, {Dong Ki} and Kim, {Dong Wook} and Shin, {Tae Joo} and Do, {Young Rag} and Jihyun Kim and Choi, {Won Jun} and Harald Ade and Min, {Byoung Koun}",
note = "Funding Information: J.‐H.K. and M.K.K. contributed equally to this work. This work was supported by the Energy Technology Development Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant (no. 20163010012570) funded by the Korean Government. This work was also partially supported by the KU‐KIST Graduate School Project. Work of H.A. and M.M.N. of NCSU was supported by the Research Opportunity Initiative grant for UNC General Administration and S.J.S. was supported by the National Science Foundation (no. DGE‐1633587). Hard X‐ray GI‐WAXS and soft X‐ray SAXS data were acquired at beamline 6D in PAL (supported in part by Ministry of Science and ICT, no. NRF‐2018R1A5A 1025224) and beamline 11.0.1.2 in the ALS at LBNL (supported by the U.S. Department of Energy, no. DE‐AC02‐05CH11231), respectively. Cheng Wang is acknowledged for help with X‐ray experimental setup and maintenance of the beamline at 11.0.1.2. The authors also acknowledge Dr. Ji‐Young Kim in the Advanced Analysis Center at KIST for assisting EBIC measurement. Funding Information: J.-H.K. and M.K.K. contributed equally to this work. This work was supported by the Energy Technology Development Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant (no. 20163010012570) funded by the Korean Government. This work was also partially supported by the KU-KIST Graduate School Project. Work of H.A. and M.M.N. of NCSU was supported by the Research Opportunity Initiative grant for UNC General Administration and S.J.S. was supported by the National Science Foundation (no. DGE-1633587). Hard X-ray GI-WAXS and soft X-ray SAXS data were acquired at beamline 6D in PAL (supported in part by Ministry of Science and ICT, no. NRF-2018R1A5A 1025224) and beamline 11.0.1.2 in the ALS at LBNL (supported by the U.S. Department of Energy, no. DE-AC02-05CH11231), respectively. Cheng Wang is acknowledged for help with X-ray experimental setup and maintenance of the beamline at 11.0.1.2. The authors also acknowledge Dr. Ji-Young Kim in the Advanced Analysis Center at KIST for assisting EBIC measurement. Publisher Copyright: {\textcopyright} 2020 Wiley-VCH GmbH",
year = "2020",
month = dec,
day = "3",
doi = "10.1002/smll.202003865",
language = "English",
volume = "16",
journal = "Small",
issn = "1613-6810",
publisher = "Wiley-VCH Verlag",
number = "48",
}