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Performance evaluation of multi-junction solar cells by spatially resolved electroluminescence microscopy.

Kong L, Wu Z, Chen S, Cao Y, Zhang Y, Li H, Kang J - Nanoscale Res Lett (2015)

Bottom Line: Meanwhile, we analyzed the relationship between electroluminescence intensity and short-circuit current density J SC.The results indicated that the gray value of the electroluminescence image corresponding to the intensity was almost proportional to J SC.This technology provides a potential way to evaluate the current matching status of multi-junction solar cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Fujian Key Laboratory of Semiconductor Materials and Applications, Xiamen University, Xiamen, 361005 People's Republic of China.

ABSTRACT
An electroluminescence microscopy combined with a spectroscopy was developed to visually analyze multi-junction solar cells. Triple-junction solar cells with different conversion efficiencies were characterized by using this system. The results showed that the mechanical damages and material defects in solar cells can be clearly distinguished, indicating a high-resolution imaging. The external quantum efficiency (EQE) measurements demonstrated that different types of defects or damages impacted cell performance in various degrees and the electric leakage mostly degraded the EQE. Meanwhile, we analyzed the relationship between electroluminescence intensity and short-circuit current density J SC. The results indicated that the gray value of the electroluminescence image corresponding to the intensity was almost proportional to J SC. This technology provides a potential way to evaluate the current matching status of multi-junction solar cells.

No MeSH data available.


Related in: MedlinePlus

Magnified EL images of GaInP and GaInAs subcells of cell C in different areas. (a, b) Area 2 in Figure 6. (c, d) Area 3 in Figure 6.
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Fig7: Magnified EL images of GaInP and GaInAs subcells of cell C in different areas. (a, b) Area 2 in Figure 6. (c, d) Area 3 in Figure 6.

Mentions: Figure 6 shows the EL images of cell C. Compared with the above two samples, this cell has relatively bright and homogeneous images. There is only an obvious dark area at the lower left corner (area ‘1’) in Figure 6b, which originated from the micro crack (red dashed oval) of the GaInP subcell. To further study other defects, we examined cell C in the magnification lens. Figure 7 shows the magnified EL images of areas ‘2’ and ‘3’ in Figure 6. It is noted that there is a long winding line at the lower left corner (blue dash) in Figure 7b, whereas it is invisible in the GaInP subcell (Figure 7a). The line runs at random angles to the electric grid, and no gray difference appears on both sides. These phenomena indicate that the defect is a hidden crack. This inside crack is small so that cell C can still be used normally, but its long-term reliability will be affected [13,14]. As for area ‘3’, there are several dark spots marked by a circle on both subcells, which might be attributed to defects penetrating through all three subcells, such as threading dislocations. In addition, one dark spot marked by a square only exists in the middle subcell, indicating a defect located in the GaInAs subcell.Figure 6


Performance evaluation of multi-junction solar cells by spatially resolved electroluminescence microscopy.

Kong L, Wu Z, Chen S, Cao Y, Zhang Y, Li H, Kang J - Nanoscale Res Lett (2015)

Magnified EL images of GaInP and GaInAs subcells of cell C in different areas. (a, b) Area 2 in Figure 6. (c, d) Area 3 in Figure 6.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385041&req=5

Fig7: Magnified EL images of GaInP and GaInAs subcells of cell C in different areas. (a, b) Area 2 in Figure 6. (c, d) Area 3 in Figure 6.
Mentions: Figure 6 shows the EL images of cell C. Compared with the above two samples, this cell has relatively bright and homogeneous images. There is only an obvious dark area at the lower left corner (area ‘1’) in Figure 6b, which originated from the micro crack (red dashed oval) of the GaInP subcell. To further study other defects, we examined cell C in the magnification lens. Figure 7 shows the magnified EL images of areas ‘2’ and ‘3’ in Figure 6. It is noted that there is a long winding line at the lower left corner (blue dash) in Figure 7b, whereas it is invisible in the GaInP subcell (Figure 7a). The line runs at random angles to the electric grid, and no gray difference appears on both sides. These phenomena indicate that the defect is a hidden crack. This inside crack is small so that cell C can still be used normally, but its long-term reliability will be affected [13,14]. As for area ‘3’, there are several dark spots marked by a circle on both subcells, which might be attributed to defects penetrating through all three subcells, such as threading dislocations. In addition, one dark spot marked by a square only exists in the middle subcell, indicating a defect located in the GaInAs subcell.Figure 6

Bottom Line: Meanwhile, we analyzed the relationship between electroluminescence intensity and short-circuit current density J SC.The results indicated that the gray value of the electroluminescence image corresponding to the intensity was almost proportional to J SC.This technology provides a potential way to evaluate the current matching status of multi-junction solar cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Fujian Key Laboratory of Semiconductor Materials and Applications, Xiamen University, Xiamen, 361005 People's Republic of China.

ABSTRACT
An electroluminescence microscopy combined with a spectroscopy was developed to visually analyze multi-junction solar cells. Triple-junction solar cells with different conversion efficiencies were characterized by using this system. The results showed that the mechanical damages and material defects in solar cells can be clearly distinguished, indicating a high-resolution imaging. The external quantum efficiency (EQE) measurements demonstrated that different types of defects or damages impacted cell performance in various degrees and the electric leakage mostly degraded the EQE. Meanwhile, we analyzed the relationship between electroluminescence intensity and short-circuit current density J SC. The results indicated that the gray value of the electroluminescence image corresponding to the intensity was almost proportional to J SC. This technology provides a potential way to evaluate the current matching status of multi-junction solar cells.

No MeSH data available.


Related in: MedlinePlus