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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

EQE curves for different cell samples.
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Fig10: EQE curves for different cell samples.

Mentions: It is known that the conversion efficiency of solar cells significantly depends on EQE, which can be affected by different kinds of defects in various degrees. To explore their relationship, we conducted EQE measurements for all cells with the results in Figure 10. As shown in Figure 10a, the quantum efficiencies for both junctions of cell A are very low, which are attributed to its serious electric leakage observed in Figure 4. During the EQE test, if there is a severe short-circuit phenomenon in a certain subcell, we could not obtain its EQE, even when a bias voltage was applied on the cell [17]. As for cell B, the EQE of the GaInP top cell is also far below the normal value, which is consistent with the large-scale nonluminous phenomenon in Figure 5a. Although the EQE of the GaInAs subcell is significantly higher than that of the GaInP subcell, the maximal value is still less than 80%, which might be explained by the previous EL images showing certain defects. Compared with cells A and B, cells C and D show better performances. The average EQE of cells C and D is about 80% and 90%, respectively. A maximal value of 96.7% was obtained in cell D at 810 nm. The slightly low EQE demonstrates that point defects or structural damages in a small area still play an unneglectable impact on conversion efficiency.Figure 10


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)

EQE curves for different cell samples.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig10: EQE curves for different cell samples.
Mentions: It is known that the conversion efficiency of solar cells significantly depends on EQE, which can be affected by different kinds of defects in various degrees. To explore their relationship, we conducted EQE measurements for all cells with the results in Figure 10. As shown in Figure 10a, the quantum efficiencies for both junctions of cell A are very low, which are attributed to its serious electric leakage observed in Figure 4. During the EQE test, if there is a severe short-circuit phenomenon in a certain subcell, we could not obtain its EQE, even when a bias voltage was applied on the cell [17]. As for cell B, the EQE of the GaInP top cell is also far below the normal value, which is consistent with the large-scale nonluminous phenomenon in Figure 5a. Although the EQE of the GaInAs subcell is significantly higher than that of the GaInP subcell, the maximal value is still less than 80%, which might be explained by the previous EL images showing certain defects. Compared with cells A and B, cells C and D show better performances. The average EQE of cells C and D is about 80% and 90%, respectively. A maximal value of 96.7% was obtained in cell D at 810 nm. The slightly low EQE demonstrates that point defects or structural damages in a small area still play an unneglectable impact on conversion efficiency.Figure 10

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