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Can plasmonic Al nanoparticles improve absorption in triple junction solar cells?

Yang L, Pillai S, Green MA - Sci Rep (2015)

Bottom Line: The particle period, diameter and the thickness of the oxide layers were optimised for the sub-cells using simulations to achieve the lowest reflection and maximum external quantum efficiencies.Our results highlight the importance of proper reference comparison, and unlike previously published results, raise doubts regarding the effectiveness of Al plasmonic nanoparticles as a suitable front-side scattering medium for broadband efficiency enhancements when compared to standard single-layer antireflection coatings.However, by embedding the nanoparticles within the dielectric layer, they have the potential to perform better than an antireflection layer and provide enhanced response from both the sub-cells.

View Article: PubMed Central - PubMed

Affiliation: 1] Australian Centre for Advanced Photovoltaics, University of New South Wales, Sydney, NSW-2052, Australia [2] College of Applied Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu 610059, China.

ABSTRACT
Plasmonic nanoparticles located on the illuminated surface of a solar cell can perform the function of an antireflection layer, as well as a scattering layer, facilitating light-trapping. Al nanoparticles have recently been proposed to aid photocurrent enhancements in GaAs photodiodes in the wavelength region of 400-900 nm by mitigating any parasitic absorption losses. Because this spectral region corresponds to the top and middle sub-cell of a typical GaInP/GaInAs/Ge triple junction solar cell, in this work, we investigated the potential of similar periodic Al nanoparticles placed on top of a thin SiO2 spacer layer that can also serve as an antireflection coating at larger thicknesses. The particle period, diameter and the thickness of the oxide layers were optimised for the sub-cells using simulations to achieve the lowest reflection and maximum external quantum efficiencies. Our results highlight the importance of proper reference comparison, and unlike previously published results, raise doubts regarding the effectiveness of Al plasmonic nanoparticles as a suitable front-side scattering medium for broadband efficiency enhancements when compared to standard single-layer antireflection coatings. However, by embedding the nanoparticles within the dielectric layer, they have the potential to perform better than an antireflection layer and provide enhanced response from both the sub-cells.

No MeSH data available.


Calculated(a) SWR and SWQE (b) Short current density for the top and middle sub-cells as a function of the thickness of the SiO2 layer without nanoparticles(c) Reflection for the optimised SLAR thicknesses of 80 nm and 140 nm for the top and middle sub-cells, respectively, along with the 25 nm spacer layer for comparison.
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f3: Calculated(a) SWR and SWQE (b) Short current density for the top and middle sub-cells as a function of the thickness of the SiO2 layer without nanoparticles(c) Reflection for the optimised SLAR thicknesses of 80 nm and 140 nm for the top and middle sub-cells, respectively, along with the 25 nm spacer layer for comparison.

Mentions: We calculated the SWR, SWQE for the two upper sub-cells with different thicknesses of SiO2 without NPs, with the SiO2 acting as a single-layer antireflection coating (SLAR) in this case. As shown in Fig. 3(a), the maxima for SWQE for the top (74.2%) and middle (82%) cells are at 80 nm and 140 nm-thick SLAR, respectively. The minimum SWR is at the thickness of 100 nm, with a value of 12%. The minimum SWR, maximum SWQE for the top cell and middle cell are not at the same thicknesses of SLAR. Fig. 3(a) also shows that the SWQE of the middle cell is higher than that of the top cell for all our calculated SLAR thicknesses, while Fig. 3(b) displays the same trend in the corresponding current density (integration spectrum 350–650 nm for the top cell and 650–900 nm for the middle cell). Therefore, the overall current of the whole device is mainly limited by the top sub-cell. The maximum currents of the top and middle sub-cells were 12.2 and 13.9 mA/cm2, respectively. While these values are more applicable to the material, structure and thickness of the layers assumed in this study and might not be a true representation of a typical 3JSC device performance, they do give an indication of the change in response from the two sub-cells. Figure 3(c) shows the reflection for the two different thicknesses of SLAR. Also included is the 25-nm SiO2 case for comparison (without NP), which clearly shows significant loss due to reflection. Based on the results from our simulations, 80-nm SiO2 gave good overall current and is a good compromise between SWQE and SWR for the two sub-cells. Therefore, it is taken as our reference for comparison purposes and will be referred to as SLAR henceforth.


Can plasmonic Al nanoparticles improve absorption in triple junction solar cells?

Yang L, Pillai S, Green MA - Sci Rep (2015)

Calculated(a) SWR and SWQE (b) Short current density for the top and middle sub-cells as a function of the thickness of the SiO2 layer without nanoparticles(c) Reflection for the optimised SLAR thicknesses of 80 nm and 140 nm for the top and middle sub-cells, respectively, along with the 25 nm spacer layer for comparison.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490398&req=5

f3: Calculated(a) SWR and SWQE (b) Short current density for the top and middle sub-cells as a function of the thickness of the SiO2 layer without nanoparticles(c) Reflection for the optimised SLAR thicknesses of 80 nm and 140 nm for the top and middle sub-cells, respectively, along with the 25 nm spacer layer for comparison.
Mentions: We calculated the SWR, SWQE for the two upper sub-cells with different thicknesses of SiO2 without NPs, with the SiO2 acting as a single-layer antireflection coating (SLAR) in this case. As shown in Fig. 3(a), the maxima for SWQE for the top (74.2%) and middle (82%) cells are at 80 nm and 140 nm-thick SLAR, respectively. The minimum SWR is at the thickness of 100 nm, with a value of 12%. The minimum SWR, maximum SWQE for the top cell and middle cell are not at the same thicknesses of SLAR. Fig. 3(a) also shows that the SWQE of the middle cell is higher than that of the top cell for all our calculated SLAR thicknesses, while Fig. 3(b) displays the same trend in the corresponding current density (integration spectrum 350–650 nm for the top cell and 650–900 nm for the middle cell). Therefore, the overall current of the whole device is mainly limited by the top sub-cell. The maximum currents of the top and middle sub-cells were 12.2 and 13.9 mA/cm2, respectively. While these values are more applicable to the material, structure and thickness of the layers assumed in this study and might not be a true representation of a typical 3JSC device performance, they do give an indication of the change in response from the two sub-cells. Figure 3(c) shows the reflection for the two different thicknesses of SLAR. Also included is the 25-nm SiO2 case for comparison (without NP), which clearly shows significant loss due to reflection. Based on the results from our simulations, 80-nm SiO2 gave good overall current and is a good compromise between SWQE and SWR for the two sub-cells. Therefore, it is taken as our reference for comparison purposes and will be referred to as SLAR henceforth.

Bottom Line: The particle period, diameter and the thickness of the oxide layers were optimised for the sub-cells using simulations to achieve the lowest reflection and maximum external quantum efficiencies.Our results highlight the importance of proper reference comparison, and unlike previously published results, raise doubts regarding the effectiveness of Al plasmonic nanoparticles as a suitable front-side scattering medium for broadband efficiency enhancements when compared to standard single-layer antireflection coatings.However, by embedding the nanoparticles within the dielectric layer, they have the potential to perform better than an antireflection layer and provide enhanced response from both the sub-cells.

View Article: PubMed Central - PubMed

Affiliation: 1] Australian Centre for Advanced Photovoltaics, University of New South Wales, Sydney, NSW-2052, Australia [2] College of Applied Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu 610059, China.

ABSTRACT
Plasmonic nanoparticles located on the illuminated surface of a solar cell can perform the function of an antireflection layer, as well as a scattering layer, facilitating light-trapping. Al nanoparticles have recently been proposed to aid photocurrent enhancements in GaAs photodiodes in the wavelength region of 400-900 nm by mitigating any parasitic absorption losses. Because this spectral region corresponds to the top and middle sub-cell of a typical GaInP/GaInAs/Ge triple junction solar cell, in this work, we investigated the potential of similar periodic Al nanoparticles placed on top of a thin SiO2 spacer layer that can also serve as an antireflection coating at larger thicknesses. The particle period, diameter and the thickness of the oxide layers were optimised for the sub-cells using simulations to achieve the lowest reflection and maximum external quantum efficiencies. Our results highlight the importance of proper reference comparison, and unlike previously published results, raise doubts regarding the effectiveness of Al plasmonic nanoparticles as a suitable front-side scattering medium for broadband efficiency enhancements when compared to standard single-layer antireflection coatings. However, by embedding the nanoparticles within the dielectric layer, they have the potential to perform better than an antireflection layer and provide enhanced response from both the sub-cells.

No MeSH data available.