Influence of Molybdenum Back Contact on the PID Effect for Cu(In,Ga)Se2 Solar Cells
Source abstract
Abstract
The authors investigated the effect of an applied high voltage (1 kV) across the thickness of a soda-lime glass substrate of Cu(In,Ga)Se2 (CIGS) thin-film solar cells. Two types of CIGS cells were tested, differing only in the deposition process of the molybdenum (Mo) back contact. Whilst one cell type was susceptible to potential induced degradation (PID), the other exhibited highly increased stability against PID. PID occurs for PID-susceptible cells after the transfer of a certain amount of charge through the soda-lime glass substrate when the Mo back contact of the cell operates as a cathode (negatively biased versus backside of the substrate). Capacitance–voltage and electron-beam-induced current measurements showed an enlarged space charge region expanding to the Mo back contact and a lowered doping density by a negative potential for PID-susceptible cells. Glow discharge optical emission spectroscopy (GDOES) revealed an accumulation of sodium (Na) in the solution-grown CdS buffer layer and a segregation on the surface of the ZnO:Al window layer for higher charges for PID-susceptible cells. Cells with increased PID immunity did not show an increase of Na for charges up to around 9 mC/cm². We demonstrate that it is possible to improve the PID stability of CIGS solar cells by modification of the molybdenum back contact.
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Research context
OpenAlex topics: Chalcogenide Semiconductor Thin Films · Quantum Dots Synthesis And Properties · Copper-based nanomaterials and applications
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), Meitnerstr. 1, 70563 Stuttgart, Germany
NICE Solar Energy GmbH, Alfred-Leikam-Str. 25, 74523 Schwäbisch Hall, Germany
NMI Natural and Medical Sciences Institute at the University of Tübingen, Markwiesenstr. 55, 72770 Reutlingen, Germany
Instituto de Energía Solar, Universidad Politécnica de Madrid, Avenida Complutense 30, 28040 Madrid, Spain
Technische Hochschule Ulm (THU), Albert-Einstein-Allee 55, 89081 Ulm, Germany
Funding
Bundesministerium für Wirtschaft und Energie
References (29)
Show source-provided references
1. Potential-induced degradation in photovoltaic modules: A critical review10.1039/C6EE02271E ↗
2. Singapore modules—optimized pv modules for the tropics10.1016/j.egypro.2012.02.047 ↗
3. PV module durability testing under high voltage biased damp heat conditions10.1016/j.egypro.2011.06.154 ↗
4. A new high-efficiency single-phase transformerless PV inverter topology10.1109/TIE.2009.2024092 ↗
5. Potassium-induced surface modification of Cu(In,Ga)Se2 thin films for high-efficiency solar cels10.1038/nmat3789 ↗
6. Efficiency enhancement of Cu(In,Ga)Se2 thin-film solar cells by post-deposition treatment with potassium fluoride10.1002/pssr.201307238 ↗
7. Analysis of leakage currents in photovoltaic modules under high-voltage bias in the fields10.1002/pip.401 ↗
8. Lechner, P., Hummel, S., Geyer, D., and Mohring, H.D. (2013, January 30). PID-Behaviour of Thin-Film and c-Si PV-Modules. Proceedings of the 28th European Photovoltaic Solar Energy Conference and Exhibition, Paris, France.
9. Boulhidja, S., Mellit, A., and Voswinckel, S. (2017, January 29). Potential-induced degradation test on CIGS photovoltaic modules. Proceedings of the 5th International Conference on Electrical Engineering—Boumerdes (ICEE-B), Boumerdes, Algeria.10.1109/ICEE-B.2017.8192051 ↗
10. Survey of potential-induced degradation in thin-film modules10.1117/1.JPE.5.053083 ↗
11. System high voltage stress degradation test in various photovoltaic modules and encapsulant sheets
12. Sakurai, K. (2018, January 10–15). Accelerated Outdoor PID Testing of CIGS Modules and Comparison with Indoor PID Tests. Proceedings of the 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC), Waikoloa Village, HI, USA.10.1109/PVSC.2018.8547927 ↗
13. Potential-induced degradation of cuin1−xgaxse2 thin film solar cells10.1109/JPHOTOV.2013.2253833 ↗
14. Potential-induced degradation of Cu(In,ga)se2 solar cells: Alkali drift and diffusion effects10.1109/JPHOTOV.2018.2858549 ↗
15. Muzzillo, C.P. (2019). Potential-induced degradation depends on leakage current and light/electrical bias in Cu(In, Ga)Se2 devices. IEEE J. Photovolt.10.1109/JPHOTOV.2019.2933189 ↗
16. Pern, F.J., Egaas, B., To, B., Jiang, C.S., Li, J.V., Glynn, S., and DeHart, C. (2009, January 7–12). A study on the humidity susceptibility of thin-film CIGS absorber. Proceedings of the 2009 34th IEEE Photovoltaic Specialists Conference (PVSC), Philadelphia, PA, USA.10.1109/PVSC.2009.5411676 ↗
17. Stability of Cu(In,Ga)Se2 solar cells; A literature review10.1016/j.solener.2016.04.010 ↗
18. Investigating PID shunting in polycrystalline CIGS devices via multi-scale, multi-technique characterization10.1109/JPHOTOV.2019.2892874 ↗
19. Analysis of potential-induced degradation in soda-lime glass borosilicate-glass Cu(In,Ga)Se2 samples
20. Characterization of the CdS/Cu(In,Ga)Se2 interface by electron beam induced currents10.1016/j.tsf.2006.12.045 ↗
21. Comparison of charge distributions in CIGS thin-film solar cells with ZnS/(Zn,Mg)O and CdS/i-ZnO buffers10.1016/j.tsf.2010.12.127 ↗
22. Recovery after potential-induced degradation of CuIn1−xGaxSe2 solar cells with cds and Zn(O,S) buffer layers
23. Growth of Cu(In,Ga)Se2 thin films by coevaporation using alkaline precursors
24. Stolt, L., Hedström, J., Kessler, J., Ruckh, M., Velthaus, K.O., and Schock, H.W. (1993, January 10–14). ZnO/CdS/Cu(In,Ga)Se2 Thin Film Solar Cells with Improved Performance. Proceedings of the Conference Records of the 23rd IEEE Photovoltaic Specialist Conference, Louisville, KY, USA.10.1063/1.108867 ↗
25. Champness, C.H., Myers, H.F., and Shih, I. (2009, January 7–12). Investigation of Sodium in Bridgman-Grown Cuinse2. Proceedings of the 34th IEEE PVSC Conference, Philadelphia, PA, USA.10.1109/PVSC.2009.5411744 ↗
26. Effect of Na doping using Na2S on the structure and photovoltaic properties of CIGS solar cells10.1016/j.cap.2010.11.019 ↗
27. Potential-induced degradation of Cu(In,Ga)Se2 photovoltaic modules10.7567/JJAP.54.08KC13 ↗
28. Voswinckel, S., Wesselak, V., Fokuhl, E., Schmidt, C., and Watzlawik, K. (2015, January 14–18). Dos and Don’ts of Leakage Current Measurement. Proceedings of the 31th European Solar Energy Conference and Exhibition, Hamburg, Germany.
29. Springer, J. (2007, January 3–7). High Voltage Stresses Applied to CIGS Thin-Film Solar Modules. Proceedings of the Conference 22nd EU PVSEC, Milan, Italy.