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Thermal imaging of solar cells is important for diagnosing non-uniform operation or point defects, which can reduce cell efficiency. However, imaging with infrared light is impractical for superstrate CdTe cells because the glass substrate blocks transmission of light. It is shown that thermoreflectance – a lock-in technique that detects changes in the reflectivity of visible light – can circumvent this problem and achieve thermal images with spatial resolution limited only by the imaging wavelength. The diagnostic is used to show that a particular defect is a resistive shunt.
References
-
-
1)
-
8. Farzaneh, M., Maize, K., Lüerßen, D., Summers, J.A., Mayer, P.M., Raad, P.E., Pipe, K.P., Shakouri, A., Ram, R.J., Hudgings, J.A.: ‘CCD-based thermoreflectance microscopy: principles and applications’, J. Phys. D, Appl. Phys., 2009, 42, p. 143001 (doi: 10.1088/0022-3727/42/14/143001).
-
2)
-
9. Kobyakov, P.S., Kephart, J.M., Sampath, W.S.: ‘Sublimation of Mg onto CdS/CdTe films fabricated by advanced deposition system’. 37th IEEE Photovoltaic Specialists Conf. (PVSC), Seattle, WA, USA, June 2011, pp. 2740–2745.
-
3)
-
2. Breitenstein, O., Langenkamp, M.: ‘Lock-in thermography’ (Springer, 2003), p. 20.
-
4)
-
3. Johnston, S., Repins, I., Sundaramoorthy, R., Jones, K.M., To, B.: ‘Correlations of photo-electro-thermal-luminescent imaging of Cu(In,Ga)Se2 with device performance, defects, and micro-structural properties’. 35th IEEE Photovoltaic Specialists Conf. (PVSC), Honolulu, HI, USA, June 2010, pp. 6–11.
-
5)
-
5. Straube, H., Breitenstein, O.: ‘Infrared lock-in thermography through glass substrates’, Solar Energy Mater. Solar Cells, 2011, 95, pp. 2768–2771 (doi: 10.1016/j.solmat.2011.05.017).
-
6)
-
6. Summers, J.A., Yang, T., Tuominen, M.T., Hudgings, J.A.: ‘High contrast, depth-resolved thermoreflectance imaging using a Nipkow disk confocal microscope’, Rev. Sci. Instrum., 2010, 81, p. 014902 (doi: 10.1063/1.3276700).
-
7)
-
4. Compaan, A.D., Gupta, A., Lee, S., Wang, S., Drayton, J.: ‘High efficiency, magnetron sputtered CdS/CdTe solar cells’, Solar Energy, 2004, 77, pp. 815–822 (doi: 10.1016/j.solener.2004.06.013).
-
8)
-
7. Matatagui, E., Thompson, A.G., Cardona, M.: ‘Thermoreflectance in semiconductors’, Phys. Rev., 1968, 176, pp. 950–960 (doi: 10.1103/PhysRev.176.950).
-
9)
-
1. Shvydka, D., Rakotoniaina, J.P., Breitenstein, O.: ‘Lock-in thermography and nonuniformity modeling of thin-film CdTe solar cells’, Appl. Phys. Lett., 2004, 84, pp. 729–731 (doi: 10.1063/1.1645322).
-
10)
-
10. Breitenstein, O., Rakotoniaina, J., Al Rifai, M., Werner, M.: ‘Shunt types in crystalline silicon solar cells’, Prog. Photovolt., Res. Appl., 2004, 12, pp. 529–538 (doi: 10.1002/pip.544).
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