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Thorough subcells diagnosis in a multi-junction solar cell via absolute electroluminescence-efficiency measurements.

Chen S, Zhu L, Yoshita M, Mochizuki T, Kim C, Akiyama H, Imaizumi M, Kanemitsu Y - Sci Rep (2015)

Bottom Line: Here, we propose a potential standard method to quantify the detailed subcell properties of multi-junction solar cells based on absolute measurements of electroluminescence (EL) external quantum efficiency in addition to the conventional solar-cell external-quantum-efficiency measurements.We demonstrate that the absolute-EL-quantum-efficiency measurements provide I-V relations of individual subcells without the need for referencing measured I-V data, which is in stark contrast to previous works.Moreover, our measurements quantify the absolute rates of junction loss, non-radiative loss, radiative loss, and luminescence coupling in the subcells, which constitute the "balance sheets" of tandem solar cells.

View Article: PubMed Central - PubMed

Affiliation: 1] Institute for Solid State Physics, University of Tokyo, and JST-CREST, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan [2] Department of Electronic Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China.

ABSTRACT
World-wide studies on multi-junction (tandem) solar cells have led to record-breaking improvements in conversion efficiencies year after year. To obtain detailed and proper feedback for solar-cell design and fabrication, it is necessary to establish standard methods for diagnosing subcells in fabricated tandem devices. Here, we propose a potential standard method to quantify the detailed subcell properties of multi-junction solar cells based on absolute measurements of electroluminescence (EL) external quantum efficiency in addition to the conventional solar-cell external-quantum-efficiency measurements. We demonstrate that the absolute-EL-quantum-efficiency measurements provide I-V relations of individual subcells without the need for referencing measured I-V data, which is in stark contrast to previous works. Moreover, our measurements quantify the absolute rates of junction loss, non-radiative loss, radiative loss, and luminescence coupling in the subcells, which constitute the "balance sheets" of tandem solar cells.

No MeSH data available.


External luminescence quantum efficiency under solar-cell operation and I-V curves of the 3-junction solar cell.(a) External luminescence quantum efficiencies (ext. lumin. quan. efficiency) of the subcells under solar-cell operation yext as a function of the photo-generated current density. (b) The theoretically calculated and experimentally measured I–V curves of the GaInP/GaAs/Ge 3-junction solar cell under the condition of 1-sun AM0. The I–V curve with ideal yext (radiative limit) was calculated under the assumption that the subcells are in a condition of the radiative limit (Rnr = 0), and the ideal conversion efficiency of the present tandem solar cell structure with ideal yext was calculated to be 35.6%. The values of Jm (current density of solar cell under maximum-output-power condition) and Jsc (current density of solar cell under short-circuit condition) marked in (a) are obtained from the experimental results as shown (b).
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f2: External luminescence quantum efficiency under solar-cell operation and I-V curves of the 3-junction solar cell.(a) External luminescence quantum efficiencies (ext. lumin. quan. efficiency) of the subcells under solar-cell operation yext as a function of the photo-generated current density. (b) The theoretically calculated and experimentally measured I–V curves of the GaInP/GaAs/Ge 3-junction solar cell under the condition of 1-sun AM0. The I–V curve with ideal yext (radiative limit) was calculated under the assumption that the subcells are in a condition of the radiative limit (Rnr = 0), and the ideal conversion efficiency of the present tandem solar cell structure with ideal yext was calculated to be 35.6%. The values of Jm (current density of solar cell under maximum-output-power condition) and Jsc (current density of solar cell under short-circuit condition) marked in (a) are obtained from the experimental results as shown (b).

Mentions: Figure 2a plots yext for 3 subcells on a log scale as a function of the solar-cell output current density J. The values of Jm (current density of solar cell under maximum-output-power condition) and Jsc (current density of solar cell under short-circuit condition) marked in Fig. 2a are obtained from the measured experimental results as shown in Fig. 2b. The solid curves in Fig. 2b represent the I–V curves of three subcells and their total under equal-subcell-current constraint. The dashed curve represents the I–V curve in the theoretical radiative limit as a reference. The open circles represent the independently measured I–V curve of the solar cell under the AM0 1-sun condition, which agrees very well with the total I–V curve derived via the EL measurement, demonstrating that the present method is reliable and feasible.


Thorough subcells diagnosis in a multi-junction solar cell via absolute electroluminescence-efficiency measurements.

Chen S, Zhu L, Yoshita M, Mochizuki T, Kim C, Akiyama H, Imaizumi M, Kanemitsu Y - Sci Rep (2015)

External luminescence quantum efficiency under solar-cell operation and I-V curves of the 3-junction solar cell.(a) External luminescence quantum efficiencies (ext. lumin. quan. efficiency) of the subcells under solar-cell operation yext as a function of the photo-generated current density. (b) The theoretically calculated and experimentally measured I–V curves of the GaInP/GaAs/Ge 3-junction solar cell under the condition of 1-sun AM0. The I–V curve with ideal yext (radiative limit) was calculated under the assumption that the subcells are in a condition of the radiative limit (Rnr = 0), and the ideal conversion efficiency of the present tandem solar cell structure with ideal yext was calculated to be 35.6%. The values of Jm (current density of solar cell under maximum-output-power condition) and Jsc (current density of solar cell under short-circuit condition) marked in (a) are obtained from the experimental results as shown (b).
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4296303&req=5

f2: External luminescence quantum efficiency under solar-cell operation and I-V curves of the 3-junction solar cell.(a) External luminescence quantum efficiencies (ext. lumin. quan. efficiency) of the subcells under solar-cell operation yext as a function of the photo-generated current density. (b) The theoretically calculated and experimentally measured I–V curves of the GaInP/GaAs/Ge 3-junction solar cell under the condition of 1-sun AM0. The I–V curve with ideal yext (radiative limit) was calculated under the assumption that the subcells are in a condition of the radiative limit (Rnr = 0), and the ideal conversion efficiency of the present tandem solar cell structure with ideal yext was calculated to be 35.6%. The values of Jm (current density of solar cell under maximum-output-power condition) and Jsc (current density of solar cell under short-circuit condition) marked in (a) are obtained from the experimental results as shown (b).
Mentions: Figure 2a plots yext for 3 subcells on a log scale as a function of the solar-cell output current density J. The values of Jm (current density of solar cell under maximum-output-power condition) and Jsc (current density of solar cell under short-circuit condition) marked in Fig. 2a are obtained from the measured experimental results as shown in Fig. 2b. The solid curves in Fig. 2b represent the I–V curves of three subcells and their total under equal-subcell-current constraint. The dashed curve represents the I–V curve in the theoretical radiative limit as a reference. The open circles represent the independently measured I–V curve of the solar cell under the AM0 1-sun condition, which agrees very well with the total I–V curve derived via the EL measurement, demonstrating that the present method is reliable and feasible.

Bottom Line: Here, we propose a potential standard method to quantify the detailed subcell properties of multi-junction solar cells based on absolute measurements of electroluminescence (EL) external quantum efficiency in addition to the conventional solar-cell external-quantum-efficiency measurements.We demonstrate that the absolute-EL-quantum-efficiency measurements provide I-V relations of individual subcells without the need for referencing measured I-V data, which is in stark contrast to previous works.Moreover, our measurements quantify the absolute rates of junction loss, non-radiative loss, radiative loss, and luminescence coupling in the subcells, which constitute the "balance sheets" of tandem solar cells.

View Article: PubMed Central - PubMed

Affiliation: 1] Institute for Solid State Physics, University of Tokyo, and JST-CREST, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan [2] Department of Electronic Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China.

ABSTRACT
World-wide studies on multi-junction (tandem) solar cells have led to record-breaking improvements in conversion efficiencies year after year. To obtain detailed and proper feedback for solar-cell design and fabrication, it is necessary to establish standard methods for diagnosing subcells in fabricated tandem devices. Here, we propose a potential standard method to quantify the detailed subcell properties of multi-junction solar cells based on absolute measurements of electroluminescence (EL) external quantum efficiency in addition to the conventional solar-cell external-quantum-efficiency measurements. We demonstrate that the absolute-EL-quantum-efficiency measurements provide I-V relations of individual subcells without the need for referencing measured I-V data, which is in stark contrast to previous works. Moreover, our measurements quantify the absolute rates of junction loss, non-radiative loss, radiative loss, and luminescence coupling in the subcells, which constitute the "balance sheets" of tandem solar cells.

No MeSH data available.