All Issue

2026 Vol.46, Issue 3 Preview Page
Multifunctional Ga2O3 Protective Layer for Enhanced Underwater Silicon Solar Cells

수중 실리콘 태양전지의 효율 향상을 위한 다기능 Ga2O3 보호층

Seongjin Ko1
,
Seojun Jeon1
,
Yebean Cho1
,
Seunghee Cho2
,
Barno Md Arifur Rahman3
,
Mooyoung Choi4
,
Joondong Kim5*
고 성진1
,
전 서준1
,
조 예빈1
,
조 승희2
,
Md Arifur Rahman Barno3
,
최 무영4
,
김 준동5*
1A Bachelor’s Degree, Department of Electrical Engineering, Incheon National University
2Master Course, Department of Electrical Engineering, Incheon National University
3Integrated M.S and Ph.D. Program, Department of Electrical Engineering, Incheon National University
4CEO, Solariver Co., Ltd, Incheon
5Dean, College of Engineering and Professor, Department of Electrical Engineering, Incheon National University
1인천대학교 전기공학과, 학사과정
2인천대학교 전기공학과, 석사과정
3인천대학교 전기공학과, 석·박사과정
4쏠라리버(주), 대표
5인천대학교 공과대학 학장, 전기공학과 교수
*Corresponding Author
30 June 2026. pp. 163-176
PDF XML Citation
Abstract

Si solar cells operated in underwater environments suffer from substantial optical reflection losses and performance degradation due to interfacial instability and thermal effects. This study introduces a multifunctional gallium oxide (Ga2O3) interfacial layer that enhances optical coupling and interfacial robustness simultaneously. The Ga2O3 layer (n ≈ 1.8–1.9) enables step-index matching between water (n ≈ 1.33) and silicon (n ≈ 3.5), thereby mitigating reflection losses. In addition, its wide bandgap (≈ 4.8 eV) effectively blocks high-energy ultraviolet (UV) radiation, thereby suppressing photo-induced degradation during underwater operation. The amorphous Ga2O3 film, which is synthesized via a low-power sputtering process. To evaluate its efficacy, the optical reflectance and photovoltaic performances of the fabricated devices were systematically characterized under simulated underwater conditions. The sputtered film contributes to an improved interfacial quality and serves as a physical barrier against moisture penetration. With an optimized thickness of 20 nm, the Ga2O3-coated device achieved a power conversion efficiency of 20.7% underwater, corresponding to an improvement of 8.4% compared with conventional Si reference devices (19.1%) tested under identical underwater conditions. These findings demonstrate a practical approach to developing high-performance and reliable underwater photovoltaic systems.

Keywords
Underwater Photovoltaics, UWPV
Gallium Oxide, Ga2O3
step-index matching
Interfacial passivation
키워드
수중 태양광
산화 갈륨
순차적 굴절률 정합
계면 패시베이션
References
1

Green, M. A., Dunlop, E. D., Yoshita, M., Kopidakis, N., Bothe, K., Siefer, G., and Hao, X., Solar Cell Efficiency Tables (Version 62), Progress in Photovoltaics: Research and Applications, Vol. 31, No. 7, pp. 651-663, 2023, https://doi.org/10.1002/pip.3726.

10.1002/pip.3726
2

Baliozian, P., Tepner, S., Fischer, M., Trube, J., Herritsch, S., Gensowski, K., Clement, F., Nold, S., and Preu, R., The International Technology Roadmap for Photovoltaics and the Significance of Its Decade-Long Projections, Proceedings of the 37th European PV Solar Energy Conference and Exhibition, pp. 420-426, September 2020, online, https://doi.org/10.4229/EUPVSEC20202020-2CV.1.59.

10.4229/EUPVSEC20202020-2CV.1.59
3

Shockley, W. and Queisser, H. J., Detailed Balance Limit of Efficiency of p-n Junction Solar Cells, Journal of Applied Physics, Vol. 32, No. 3, pp. 510-519, 1961, https://doi.org/10.1063/1.1736034.

10.1063/1.1736034
4

Green, M. A., Single Junction Cells, In: Third Generation Photovoltaics, Springer, Berlin, Germany, pp. 35-58, 2006, https://doi.org/10.1007/3-540-26563-5_4.

10.1007/3-540-26563-5_4
5

Würfel, P., The Chemical Potential of Radiation, Journal of Physics C: Solid State Physics, Vol. 15, No. 18, pp. 3967-3985, 1982, https://doi.org/10.1088/0022-3719/15/18/012.

10.1088/0022-3719/15/18/012
6

Born, M. and Wolf, E., Principles of Optics: Electromagnetic Theory of Propagation, Interference and Diffraction of Light (7th ed.), Cambridge University Press, Cambridge, United Kingdom, 2013, https://doi.org/10.1017/CBO9781139644181.

10.1017/CBO9781139644181
7

Green, M. A., Self-Consistent Optical Parameters of Intrinsic Silicon at 300 K Including Temperature Coefficients, Solar Energy Materials and Solar Cells, Vol. 92, No. 11, pp. 1305-1310, 2008, https://doi.org/10.1016/j.solmat.2008.06.009.

10.1016/j.solmat.2008.06.009
8

Aberle, A. G., Surface Passivation of Crystalline Silicon Solar Cells: A Review, Progress in Photovoltaics: Research and Applications, Vol. 8, No. 5, pp. 473-487, 2000, https://doi.org/10.1002/1099-159X(200009/10)8:5<473::AID-PIP337>3.0.CO;2-D.

10.1002/1099-159X(200009/10)8:5<473::AID-PIP337>3.0.CO;2-D
9

Hezel, R. and Jaeger, K., Low-Temperature Surface Passivation of Silicon for Solar Cells, Journal of The Electrochemical Society, Vol. 136, No. 2, pp. 518-523, 1989, https://doi.org/10.1149/1.2096673.

10.1149/1.2096673
10

Cazzaniga, R., Cicu, M., Rosa-Clot, M., Rosa-Clot, P., Tina, G. M., and Ventura, C., Floating Photovoltaic Plants: Performance Analysis and Design Solutions, Renewable and Sustainable Energy Reviews, Vol. 81, pp. 1730-1741, 2018, https://doi.org/10.1016/j.rser.2017.05.269.

10.1016/j.rser.2017.05.269
11

Wang, Y., Fang, Z., Zhu, L., Huang, Q., Zhang, Y., and Zhang, Z., The Performance of Silicon Solar Cells Operated in Liquids, Applied Energy, Vol. 86, No. 7-8, pp. 1037-1042, 2009, https://doi.org/10.1016/j.apenergy.2008.08.020.

10.1016/j.apenergy.2008.08.020
12

Hale, G. M. and Querry, M. R., Optical Constants of Water in the 200 nm to 200 μm Wavelength Region, Applied Optics, Vol. 12, No. 3, pp. 555-563, 1973, https://doi.org/10.1364/AO.12.000555.

10.1364/AO.12.000555
13

Krauter, S., Increased Electrical Yield via Water Flow over the Front of Photovoltaic Panels, Solar Energy Materials and Solar Cells, Vol. 82, No. 1-2, pp. 131-137, 2004, https://doi.org/10.1016/j.solmat.2004.01.011.

10.1016/j.solmat.2004.01.011
14

Teo, H. G., Lee, P. S., and Hawlader, M. N. A., An Active Cooling System for Photovoltaic Modules, Applied Energy, Vol. 90, No. 1, pp. 309-315, 2012, https://doi.org/10.1016/j.apenergy.2011.01.017.

10.1016/j.apenergy.2011.01.017
15

Minnaert, B. and Veelaert, P., A Proposal for Typical Artificial Light Sources for the Characterization of Indoor Photovoltaic Applications, Energies, Vol. 7, No. 3, pp. 1500-1516, 2014, https://doi.org/10.3390/en7031500.

10.3390/en7031500
16

Skoplaki, E. and Palyvos, J. A., On the Temperature Dependence of Photovoltaic Module Electrical Performance: A Review of Efficiency/Power Correlations, Solar Energy, Vol. 83, No. 5, pp. 614-624, 2009, https://doi.org/10.1016/j.solener.2008.10.008.

10.1016/j.solener.2008.10.008
17

Mori, K., Nakano, Y., Ueno, M., Shi, J., Saitoh, T., and Sugimoto, H., Low Temperature Silicon Oxide and Nitride for Surface Passivation of Silicon Solar Cells, Solar Energy Materials and Solar Cells, Vol. 71, No. 2, pp. 197-211, 2002, https://doi.org/10.1016/S0927-0248(01)00058-7.

10.1016/S0927-0248(01)00058-7
18

Pearton, S. J., Yang, J., Cary, P. H., Ren, F., Kim, J., Tadjer, M. J., and Mastro, M. A., A Review of Ga2O3 Materials, Processing, and Devices, Applied Physics Reviews, Vol. 5, No. 1, 011301, 2018, https://doi.org/10.1063/1.5006941.

10.1063/1.5006941
19

Higashiwaki, M., Sasaki, K., Murakami, H., Kumagai, Y., Koukitu, A., Kuramata, A., Masui, T., and Yamakoshi, S., Recent Progress in Ga2O3 Power Devices, Semiconductor Science and Technology, Vol. 31, No. 3, 034001, 2016, https://doi.org/10.1088/0268-1242/31/3/034001.

10.1088/0268-1242/31/3/034001
20

George, S. M., Atomic Layer Deposition: An Overview, Chemical Reviews, Vol. 110, No. 1, pp. 111-131, 2010, https://doi.org/10.1021/cr900056b.

10.1021/cr900056b
21

Hoex, B., Schmidt, J., Pohl, P., van de Sanden, M. C. M., and Kessels, W. M. M., Silicon Surface Passivation by Atomic Layer Deposited Al2O3, Journal of Applied Physics, Vol. 104, No. 4, 044903, 2008, https://doi.org/10.1063/1.2963707.

10.1063/1.2963707
22

Burrows, P. E., Graff, G. L., Gross, M. E., Martin, P. M., Shi, M. K., Hall, M., Mast, E., Bonham, C., Bennett, W., and Sullivan, M. B., Ultra Barrier Flexible Substrates for Flat Panel Displays, Displays, Vol. 22, No. 2, pp. 65-69, 2001, https://doi.org/10.1016/S0141-9382(00)00064-0.

10.1016/S0141-9382(00)00064-0
23

Clugston, D. A. and Basore, P. A., PC1D Version 5: 32-Bit Solar Cell Modeling on Personal Computers, Conference Record of the Twenty Sixth IEEE Photovoltaic Specialists Conference, pp. 207-210, September 1997, Anaheim, CA, USA, https://doi.org/10.1109/PVSC.1997.654065.

10.1109/PVSC.1997.654065
24

Pyngrope, D., Biswas, M., Kumar, S. S., Majumdar, S., and Bag, A., RF Magnetron Sputtering of Ga2O3 Thin Films: Analysis of Thermal Annealing Induced Tuning of Structural, Optical Characteristics, and Energy Band Alignments, Materials Science in Semiconductor Processing, Vol. 174, 108243, 2024, https://doi.org/10.1016/j.mssp.2024.108243.

10.1016/j.mssp.2024.108243
25

Schmidt, J., Merkle, A., Brendel, R., Hoex, B., van de Sanden, M. C. M., and Kessels, W. M. M., Surface Passivation of High-Efficiency Silicon Solar Cells by Atomic-Layer-Deposited Al2O3, Progress in Photovoltaics: Research and Applications, Vol. 16, No. 6, pp. 461-466, 2008, https://doi.org/10.1002/pip.823.

10.1002/pip.823
26

Basore, P. A., Numerical Modeling of Textured Silicon Solar Cells Using PC-1D, IEEE Transactions on Electron Devices, Vol. 37, No. 2, pp. 337-343, 1990, https://doi.org/10.1109/16.46362.

10.1109/16.46362
27

Patel, M., Barno, M. A. R., Barichello, J., Thi, S. V., Cho, S., Matteocci, F., Di Carlo, A., Wong, C.-P., and Kim, J., Water-Driven Photovoltaics: Enhancing Performance through Water Media in the Active Layer, Materials Today Sustainability, Vol. 31, 101158, 2025, https://doi.org/10.1016/j.mtsust.2025.101158.

10.1016/j.mtsust.2025.101158
28

Le, A. H. T., Dao, V. A., Pham, D. P., Kim, S., Dutta, S., Thi Nguyen, C. P., Lee, Y., Kim, Y., and Yi, J., Damage to Passivation Contact in Silicon Heterojunction Solar Cells by ITO Sputtering under Various Plasma Excitation Modes, Solar Energy Materials and Solar Cells, Vol. 192, pp. 36-43, 2019, https://doi.org/10.1016/j.solmat.2018.12.001.

10.1016/j.solmat.2018.12.001
29

Wan, Y., Bullock, J., and Cuevas, A., Tantalum Oxide/Silicon Nitride: A Negatively Charged Surface Passivation Stack for Silicon Solar Cells, Applied Physics Letters, Vol. 106, No. 20, 201601, 2015, https://doi.org/10.1063/1.4921416.

10.1063/1.4921416
30

Yang, X., Wan, Y., Wang, Y., Zhao, J., Wang, C., Cheng, F., and Yu, S., Preparation, Characterization and Properties of B-Doped β-Ga2O3 Film, Journal of Alloys and Compounds, Vol. 1020, 179343, 2025, https://doi.org/10.1016/j.jallcom.2025.179343.

10.1016/j.jallcom.2025.179343
31

Wei, S., Shi, Q., Liu, Y., and Yang, C.-F., Sputtering Growth of Nitrogen-Doped Ga2O3 Films and Applications of Photodetectors, Sensors and Materials, Vol. 36, No. 5, pp. 2127-2139, 2024, https://doi.org/10.18494/SAM4890.

10.18494/SAM4890
32

Qiu, D., Duan, W., Lambertz, A., Eberst, A., Bittkau, K., Rau, U., and Ding, K., Transparent Conductive Oxide Sputtering Damage on Contact Passivation in Silicon Heterojunction Solar Cells with Hydrogenated Nanocrystalline Silicon, Solar RRL, Vol. 6, No. 10, 2200651, 2022, https://doi.org/10.1002/solr.202200651.

10.1002/solr.202200651
33

Czigány, Z. and Hultman, L., Interpretation of Electron Diffraction Patterns from Amorphous and Fullerene-Like Carbon Allotropes, Ultramicroscopy, Vol. 110, No. 7, pp. 815-819, 2010, https://doi.org/10.1016/j.ultramic.2010.02.005.

10.1016/j.ultramic.2010.02.005
34

Allen, T. G. and Cuevas, A., Plasma Enhanced Atomic Layer Deposition of Gallium Oxide on Crystalline Silicon: Demonstration of Surface Passivation and Negative Interfacial Charge, physica status solidi (RRL) - Rapid Research Letters, Vol. 9, No. 4, pp. 220-224, 2015, https://doi.org/10.1002/pssr.201510056.

10.1002/pssr.201510056
35

Daimon, M. and Masumura, A., Measurement of the Refractive Index of Distilled Water from the Near-Infrared Region to the Ultraviolet Region, Applied Optics, Vol. 46, No. 18, pp. 3811-3820, 2007, https://doi.org/10.1364/AO.46.003811.

10.1364/AO.46.003811
36

Aydin, E., Altinkaya, C., Smirnov, Y., Yaqin, M. A., Zanoni, K. P. S., Paliwal, A., Firdaus, Y., Allen, T. G., Anthopoulos, T. D., Bolink, H. J., Morales Masis, M., and De Wolf, S., Sputtered Transparent Electrodes for Optoelectronic Devices: Induced Damage and Mitigation Strategies, Matter, Vol. 4, No. 11, pp. 3549-3584, 2021, https://doi.org/10.1016/j.matt.2021.09.021.

10.1016/j.matt.2021.09.021
37

Swaby, B., Simple Computations Involving Two-Component Symmetric Trilayers, Applied Optics, Vol. 41, No. 30, pp. 5984-5988, 2002, https://doi.org/10.1364/AO.41.005984.

10.1364/AO.41.005984
38

Aarik, L., Mändar, H., Kasikov, A., Tarre, A., and Aarik, J., Optical Properties of Ga2O3 Thin Films Grown by Atomic Layer Deposition Using GaI3 and O3 as Precursors, Journal of Materials Chemistry C, Vol. 12, pp. 10562-10574, 2024, https://doi.org/10.1039/D4TC01846J.

10.1039/D4TC01846J
39

Orita, M., Ohta, H., Hirano, M., and Hosono, H., Deep-Ultraviolet Transparent Conductive β-Ga2O3 Thin Films, Applied Physics Letters, Vol. 77, No. 25, pp. 4166-4168, 2000, https://doi.org/10.1063/1.1330559.

10.1063/1.1330559
40

Härtel, M., Li, B., Mariotti, S., Wagner, P., Ruske, F., Albrecht, S., and Szyszka, B., Reducing Sputter Damage-Induced Recombination Losses During Deposition of the Transparent Front-Electrode for Monolithic Perovskite/Silicon Tandem Solar Cells, Solar Energy Materials and Solar Cells, Vol. 252, 112180, 2023, https://doi.org/10.1016/j.solmat.2023.112180.

10.1016/j.solmat.2023.112180
41

Röhr, J. A., Lipton, J., Kong, J., Maclean, S. A., and Taylor, A. D., Efficiency Limits of Underwater Solar Cells, Joule, Vol. 4, No. 4, pp. 840-849, 2020, https://doi.org/10.1016/j.joule.2020.02.005.

10.1016/j.joule.2020.02.005
42

Zhang, A., Sartor, B. E., Röhr, J. A., and Taylor, A. D., LED-Based Characterization of Solar Cells for Underwater Applications, STAR Protocols, Vol. 5, No. 1, 102833, 2024, https://doi.org/10.1016/j.xpro.2023.102833.

10.1016/j.xpro.2023.10283338280200PMC10840341
43

Naaz, N., Dutta, S., Goel, S., and Ramaswamy, K., Calibrating Underwater Photovoltaic Performance, Renewable Energy, Vol. 247, 122993, 2025, https://doi.org/10.1016/j.renene.2025.122993.

10.1016/j.renene.2025.122993
44

Uvarov, A., Baranov, A., Pozdeev, V., Maksimova, A., Vyacheslavova, E., Mikhaylov, O., Yarchuk, E., Kirilenko, D., and Gudovskikh, A., Low-Temperature Plasma-Enhanced Atomic Layer Deposition of Ga2O3 Films Using N2O Plasma for Silicon Surface Passivation, Applied Surface Science, Vol. 719, 165092, 2026, https://doi.org/10.1016/j.apsusc.2025.165092.

10.1016/j.apsusc.2025.165092
45

Chhajed, S., Schubert, M. F., Kim, J. K., and Schubert, E. F., Nanostructured Multilayer Graded-Index Antireflection Coating for Si Solar Cells with Broadband and Omnidirectional Characteristics, Applied Physics Letters, Vol. 93, No. 25, 251108, 2008, https://doi.org/10.1063/1.3050463.

10.1063/1.3050463
Information
  • Publisher :Korean Solar Energy Society
  • Publisher(Ko) :한국태양에너지학회
  • Journal Title :Journal of the Korean Solar Energy Society
  • Journal Title(Ko) :한국태양에너지학회 논문집
  • Volume : 46
  • No :3
  • Pages :163-176
  • Received Date : 2026-03-19
  • Revised Date : 2026-04-20
  • Accepted Date : 2026-05-17
  • DOI :https://doi.org/10.7836/kses.2026.46.3.163
Journal Informaiton Journal of the Korean Solar Energy Society Journal of the Korean Solar Energy Society
Online Submission
  • NRF
  • KOFST
  • crossref crossmark
  • crossref cited-by
  • crosscheck
  • orcid
  • open access
  • ccl
Journal Informaiton Journal Informaiton - close