PHOTOVOLTA IC DEVICES – Part 8-1: Measurement of spectral responsivity of multi-junction photovoltaic PV devices This part of IEC 6 9 4 gives g idan e f or the me s rement of the sp ctra
General 9 9.3.2 Correcting the SR of the second junction (for the coupling J1 J2) 1 0 9.3.3 Correcting the SR of the third junction (for the coupling J 1 J2 and J2
The procedure for correcting luminescent coupling involves indexing various junctions \( J_i \) starting from the highest bandgap, with \( J_1 \) as the top junction This method focuses solely on the coupling between adjacent junctions, disregarding direct coupling such as \( J_1 \to J_3 \), as the middle junction must be sufficiently thick to absorb all luminescence from \( J_1 \) Corrections are applied sequentially; the second junction is adjusted for the effects of \( J_1 \to J_2 \) coupling, followed by the third junction, which is corrected for the combined effects of \( J_1 \to J_2 \) and \( J_2 \to J_3 \), and so on.
9.3.2 Correcting the SR of the second junction (for the coupling J 1 J 2 )
9.3.2.1 This correction applies for the bottom junction SR of a two-junction PV device, or in the second junction SR of a three (or more) junction PV device
9.3.2.2 Identify a wavelength range [흀ퟏ ,흀ퟐ ] where: a) the top junction has a SR close to its maximum; b) the SR curve is relatively smooth
9.3.2.3 For a wavelength 흀ퟎ near the midpoint of the range [흀 ퟏ ,흀 ퟐ ], calculate the ratio 휷 ퟏퟐ ( ퟐ )
훽 12 ( 2 ) = 푆푆 푆푆 2 푚푚푚푚 ( 휆 0 )
1푚푎푎 ( 휆0 ) (2) where
푆푆 푖 푚푚푚푚 ( 휆 ) refers to the measured SR curve of the i th junction;
푆푆 푖 푚푎푎 (휆) refers to the actual (i e corrected) SR curve of the ith junction
For the top junction there is no correction, so:
푆푆 1 푚푎푎 (휆) =푆푆 1 푚푚푚푚 (휆) (3)
9.3.2.4 Using the result of formula (2), estimate the correction factor 흂 ퟏퟐ ( ퟐ )
9.3.2.5 Calculate the corrected second junction 푺푺 ퟐ 풂풂풂 (흀) curve as:
푆푆 2 푚푎푎 (휆) = �1 +휈 12 ( 2 ) � ∙ 푆푆 2 푚푚푚푚 (휆)− 휈 12 ( 2 ) ∙ 푆푆 1 푚푎푎 (휆) = 푆푆 1−훽 2 푚푚푚푚 ( 휆 )
12 ( 2)푆푆 1 푚푎푎 (휆) (5)
To achieve an average value of \$S_{S2}^{aaa}\$ equal to zero over the interval \([h_1, h_2]\), incrementally adjust the value of \$h_{12}(2)\$ and repeat the process outlined in section 9.3.2.5 While a formal calculation of the average value of the corrected SR can be performed, a simple visual inspection of the second junction SR curve typically provides sufficient accuracy, indicating that the average SR is approximately zero.
To correct the spectral response (SR) of the third junction in a photovoltaic (PV) device, applicable to both three-junction and multi-junction configurations, it is essential to determine two constants, $\nu_{12}^{(3)}$ and $\nu_{23}^{(3)}$ Prior to this correction, the maximum spectral sensitivity, $SS2_{maa}(\lambda)$, must be established by following the previously outlined procedure for adjusting the SR of the second junction.
To identify a wavelength range \([\lambda_1^T, \lambda_2^T]\) for the top junction responsivity, it is essential to ensure that the top junction exhibits a signal responsivity (SR) near its maximum and that the SR curve remains relatively smooth within this range.
9.3.3.3 For a wavelength 흀ퟎ 푻 near the middle of the range [흀ퟏ 푻 ,흀ퟐ 푻 ], calculate:
훽 12 ( 3 ) = 푆푆 푆푆 3 푚푚푚푚 ( 휆 0푇 )
1푚푎푎 ( 휆 0푇 ) (6)
Identify a wavelength range \([\lambda_1^M, \lambda_2^M]\) within the middle junction responsivity region, ensuring that the middle junction exhibits a signal responsivity (SR) near its maximum and that the SR curve remains relatively smooth.
9.3.3.5 For a wavelength 흀 ퟎ 푴 near the middle of the range [흀 ퟏ 푴 ,흀 ퟐ 푴 ], calculate:
훽 23 ( 3 ) = 푆푆 푆푆 3 푚푚푚푚 ( 휆 0푀 )
2푚푎푎 ( 휆 0푀 ) (7)
9.3.3.6 Estimate the first correction factor 흂 ퟏퟐ ( ퟑ ) :
9.3.3.7 Estimate the second correction factor 흂 ퟐퟑ ( ퟑ ) :
( 훽 23 ( 3 ) +훽 12 ( 3 ) ) (9) 9.3.3.8 Calculate the corrected third junction 푺푺 ퟑ 풂풂풂 ( 흀 ) curve as:
The equation for \( SS3_{maa}(\lambda) \) is given by:\[SS3_{maa}(\lambda) = \left(1 + \nu_{23}(3) + \nu_{12}(3) \nu_{23}(3)\right) \cdot SS3_{mmmm}(\lambda) - \nu_{23}(3) \cdot SS2_{maa}(\lambda) - \nu_{12}(3) \nu_{23}(3) \cdot SS1_{maa}(\lambda)\]This formula illustrates the relationship between different variables and their contributions to the overall function \( SS3_{maa}(\lambda) \).
To achieve an average value of \$SS3_{maa}\$ equal to zero over the specified ranges of \$[λ_1^T, λ_2^T]\$ and \$[λ_1^M, λ_2^M]\$, incrementally adjust the values of \$\alpha_{12}(3)\$ and \$\alpha_{23}(3)\$, and repeat the process outlined in section 9.3.3.8 While a formal calculation of the average values of the corrected SR can be performed, a simple visual inspection is often sufficient to confirm that the SR appears to be zero within the two wavelength ranges.
9.3.4 Correcting the SR of the fourth (or higher) junction
The fourth (or higher) junction's SR can be accurately corrected by disregarding the influence of the upper junctions and focusing solely on the couplings from the two preceding junctions.
To address the fourth junction, first, correct the SR of the second and third junction as outlined in sections 9.3.2 and 9.3.3 Next, repeat the procedure for the third junction, ensuring that all subscripts and superscripts are increased by 1.
Correcting the SR of higher junctions is a straightforward extension of this procedure
For additional details see bibliography
Upon completion of the procedure, the test agency will prepare a certified report of the SR measurements Each certificate or test report will include all items mandated by IEC 60904-8, along with specific details for each tested junction.
• Identification of bias light applied including wavelengths, bandwidths and irradiances;
• Description of the method adopted for bias-voltage determination;
• External bias voltage actually applied;
• Documentation of corrections applied, if any;
• Statement of the estimated uncertainty of the calibration or test results applicable to the measurement procedures for multi-junction devices
In their 2012 study published in the IEEE Journal of Photovoltaics, M A Steiner and colleagues explore the phase effects that influence the measurements of quantum efficiency and luminescent coupling in multijunction solar cells Their research, detailed in Volume 2, Issue 4, pages 424-433, provides valuable insights into optimizing solar cell performance through a better understanding of these critical factors.
Myles A Steiner et al conducted a study titled “Measuring IV curves and subcell photovoltaic currents in the presence of luminescent coupling,” published in the Journal of Photovoltaics, Volume 3 The research focuses on the measurement techniques for IV curves and photovoltaic currents in subcells, emphasizing the impact of luminescent coupling on these measurements.
M Meusel, R Adelhelm, F Dimroth, A.W Bett, and W Warta, Spectral Mismatch Correction and Spectrometric Characterization of Monolithic III-V Multi-Junction Solar Cells Progress in Photovoltaics: Research and Applications, 2002, 1 0(4): pp 243-255
G Siefer, C Baur, and A.W Bett, "External Quantum Efficiency Measurements of Germanium Bottom Subcells: Measurement Artifacts and Correction Procedures",Proceedings of the 35th IEEE Photovoltaic Specialists Conference, 201 0, Honolulu, HI pp 000704 – 07
Y Hishikawa, Y Tsuno, K Kurokawa, "Spectral response measurements of PV modules and multi-junction devices", Proceedings of 22 nd European Photovoltaics Solar Energy Conference, 2007, Milan, Italy, pp.2765-2769
Y Tsuno, Y Hishikawa, K Kurokawa, "A method for spectral response measurements of various PV modules", Proceedings of 23 rd European Photovoltaics Solar Energy Conference,
T Sogabe, A Ogura, C.-Y Hung, V Evstropov, M Mintairov, M Shvarts, Y Okada,
"Experimental characterization and self-consistent modeling of luminescence coupling effect in III-V multijunction solar cells", Applied Physics Letters, 1 03, 263907, 201 3; doi:
7.2 Matériel de mesure de la sensibilité spectrale à l'aide d'une source de lumière continue 20
7.3 Matériel de mesure de la sensibilité spectrale à l'aide d'une source de lumière pulsée 20
7.4 Matériel de mesure de modules connectés en série 20
8 Mesurage de la sensibilité spectrale 20
8.1 Mesurage de la sensibilité spectrale à l'aide d'une source de lumière continue 20
8.2 Mesurage de la sensibilité spectrale à l'aide d'une source de lumière pulsée 20
8.3 Mesurage de modules connectés en série 21
9 Correction de la sensibilité spectrale mesurée 21
9.3.2 Correction de la sensibilité spectrale de la deuxième jonction (pour le couplage J1 J2) 22
9.3.3 Correction de la sensibilité spectrale de la troisième jonction (pour le couplage J1 J2 et J2 J3) 23
9.3.4 Correction de la sensibilité spectrale de la quatrième jonction (ou jonction supérieure) 24
Partie 8-1 : Mesurage de la sensibilité spectrale des dispositifs photovoltạques (PV) multijonctions
The International Electrotechnical Commission (IEC) is a global standards organization comprising national electrotechnical committees Its primary goal is to promote international cooperation on standardization in the fields of electricity and electronics To achieve this, the IEC publishes international standards, technical specifications, technical reports, publicly accessible specifications (PAS), and guides, collectively referred to as "IEC Publications." The development of these publications involves study committees, with participation from any interested national committee Additionally, international, governmental, and non-governmental organizations collaborate with the IEC in its efforts The IEC also works closely with the International Organization for Standardization (ISO) under an agreement between the two organizations.
The official decisions or agreements of the IEC on technical matters aim to achieve international consensus on the studied topics, as each study committee includes representatives from the relevant national IEC committees.
The IEC publications are issued as international recommendations and are approved by the national committees of the IEC The IEC makes every reasonable effort to ensure the technical accuracy of its publications; however, it cannot be held responsible for any misuse or misinterpretation by end users.
Généralités
The main difference between measuring the spectral sensitivity of single-junction devices and multi-junction photovoltaic (PV) devices lies in the requirement for specific pseudolight, as outlined in Article 5 Suitable equipment for providing this pseudolight includes light-emitting diodes (LEDs), broadband light sources with appropriate optical filters, and other suitable light sources, such as unfocused lasers.
La source de tension de polarisation externe, qui est facultative pour mesurer la sensibilité spectrale des dispositifs à jonction unique, devient obligatoire pour mesurer celle des dispositifs multijonctions.
Matériel de mesure de la sensibilité spectrale à l'aide d'une source de lumière continue
Le matériel doit être similaire à celui présenté dans l'IEC 60904-8 pour mesurer la sensibilité spectrale des dispositifs PV à jonction unique par modification de la pseudolumière (voir l’Article 5).
Matériel de mesure de la sensibilité spectrale à l'aide d'une source de lumière pulsée
The equipment required to measure spectral sensitivity using a single pulsed light source should be similar to that outlined in IEC 60904-8 for assessing the spectral sensitivity of single-junction PV devices, with the addition of pseudolight.
Matériel de mesure de modules connectés en série
The equipment used must be similar to that specified in IEC 60904-8 for measuring the spectral sensitivity of single-junction PV devices through the modification of pseudolight The additional pseudolight applied to the rest of the module should be capable of generating photovoltaic currents in all junctions, either by adding multiple narrow-band light sources or by using a broadband light source.
8 Mesurage de la sensibilité spectrale
Mesurage de la sensibilité spectrale à l'aide d'une source de lumière
Le mesurage s'apparente à celui des dispositifs PV à jonction unique avec modification de la pseudolumière (voir l’Article 5) De plus, une tension de polarisation externe adaptée doit être appliquée (voir l’Article 6)
By employing chopped light and a locking technique, it is essential to record not only the amplitude of the signal but also, to the extent possible, its phase, as both contain potentially valuable information (see bibliography).
Mesurage de la sensibilité spectrale à l'aide d'une source de lumière pulsée
Le mesurage s'apparente à celui des dispositifs PV à jonction unique avec une pseudolumière supplémentaire (voir l’Article 5) De plus, une tension de polarisation externe adaptée doit être appliquée (voir l’Article 6).
Mesurage de modules connectés en série
The measurement process is similar to that of single-junction PV devices, with modifications to the pseudolight for the target cell The additional pseudolight applied to the rest of the module must generate photovoltaic currents in all junctions of the cells not under test, which should exceed the maximum photovoltaic current generated in the junction being tested within the target cell The polarization voltage conditions are already addressed by IEC 60904-8.
9 Correction de la sensibilité spectrale mesurée
Généralités
Measured spectral sensitivity can deviate from true spectral sensitivity due to junction shunting and/or luminescent coupling In both instances, it is essential to correct the measured spectral sensitivity.
The shunt in target junctions results in a non-zero slope (near the short-circuit point) of the junction's I-V curve, which shifts the operating voltage and consequently leads to a non-zero contribution from other junctions to the measured spectral sensitivity.
Luminescent coupling in multi-junction photovoltaic (PV) devices is a phenomenon where radiative recombination in a high bandgap junction emits photons towards a lower bandgap junction When these photons are absorbed, they generate additional photovoltaic current in the latter junction This effect is crucial for measuring spectral sensitivity and light polarization, as it requires one of the junctions to limit the current, thereby necessitating that the other junctions operate in forward bias.
In a multijunction photovoltaic (PV) device, the junction's performance is affected by shunting and/or luminescent coupling, leading to a non-zero spectral sensitivity at shorter wavelengths (tails) This sensitivity is observed within the wavelength range of a high bandgap filter junction.
To differentiate between shunt and luminescent coupling when uncertain about the origin, follow the outlined procedure and apply the appropriate correction method Use monochromatic light within the wavelength range of the tail, adjust the applied polarization voltage, and monitor the signal amplitude: if the PV device is dominated by shunt, the signal amplitude will vary with the polarization voltage, whereas if it is dominated by luminescent coupling, the amplitude should remain constant It is important to note that luminescent coupling may depend on the polarization voltage or the illumination of the pseudolight, which can complicate the distinction.
Des effets similaires peuvent ộgalement apparaợtre par suite du claquage par polarisation inverse dans la jonction à limitation en courant.
Correction du shunt
La correction du shunt est décrite ci-dessous D'abord, la sensibilité spectrale de toutes les jonctions est mesurée
La formule (1 ) suivante exprime la sensibilité spectrale mesurée et peut être utilisée pour la corriger
푆푆푚푚푚푚 = ∑ 푆푆 푖
푑푑푖푑푑푖
∑ 푛 푖=1 푑푑푖 푑푑푖 (1 ) ó
SR meas est la sensibilité spectrale mesurée; n est le nombre de jonctions dans le dispositif multijonction; i est l'indice de jonction;
The true spectral sensitivity of the i-th junction, denoted as SR i, is determined by the slope of the I-V curve, represented as dV i /dI i, at its operating point during the measurement of spectral sensitivity.
Correcting the measured spectral sensitivity can yield the true spectral sensitivity of a junction by relying on prior knowledge or assumptions about spectral sensitivity at specific wavelengths This process typically involves identifying a measurement artifact (non-zero spectral sensitivity) in a wavelength range where the junction material is expected to have zero spectral sensitivity Correction factors can be calculated at specific wavelengths and then applied across the entire measurement wavelength range, without needing explicit knowledge of the current-voltage curve In cases of the aforementioned artifact, the spectral sensitivity of another junction is scaled and deduced to eliminate the artifact Furthermore, the spectral sensitivity of the junction with the artifact is increased by dividing it by (1 - scaling factor).
Se reporter à la bibliographie pour de plus amples informations.
Correction du couplage luminescent
Généralités
Dans la procédure suivante de correction du couplage luminescent, les différentes jonctions J i sont indexées à partir de la largeur de bande interdite la plus élevée (1 = jonction supérieure,
The procedure focuses solely on the coupling between adjacent junctions, disregarding direct coupling such as from J1 to J3 This is because the intermediate junction must be sufficiently thick to absorb all luminescence from J1 Corrections are applied sequentially, meaning that the effects of coupling from J1 to J2 in the second junction are corrected first, followed by the combined effects of J1 to J2 and J2 to J3 in the third junction, and so on.
Correction de la sensibilité spectrale de la deuxième jonction (pour le
9.3.2.1 Cette correction s'applique à la sensibilité spectrale de la jonction inférieure d'un dispositif PV à deux jonctions ou à la sensibilité spectrale de la deuxième jonction d'un dispositif PV à trois jonctions (voire plus)
9.3.2.2 Identifier une plage de longueurs d'onde [흀 ퟏ ,흀 ퟐ ] dans laquelle: a) la sensibilité spectrale de la jonction supérieure est proche de sa valeur maximale; b) la courbe de sensibilité spectrale est relativement lisse
9.3.2.3 Pour une longueur d'onde 흀 ퟎ proche du point milieu de la plage [흀 ퟏ ,흀 ퟐ ], calculer le rapport 휷 ퟏퟐ ( ퟐ )
훽 12 ( 2 ) = 푆푆 푆푆 2 푚푚푚푚 ( 휆 0 )
푆푆 푖 푚푚푚푚 (휆) se rapporte à la courbe de sensibilité spectrale mesurée de la i ème jonction;
푆푆 푖 푚푎푎 (휆) se rapporte à la courbe de sensibilité spectrale réelle (c'est-à-dire corrigée) mesurée de la i ème jonction
La jonction supérieure ne fait l'objet d'aucune correction, donc:
푆푆 1 푚푎푎 (휆) =푆푆 1 푚푚푚푚 (휆) (3)
9.3.2.4 À l'aide des résultats de la formule (2), estimer le facteur de correction 흂 ퟏퟐ ( ퟐ )
9.3.2.5 Calculer la courbe 푺푺ퟐ 풂풂풂 (흀 ) de la deuxième jonction corrigée grâce à la formule (5) ci-dessous:
푆푆2 푚푎푎 (휆) = �1 +휈 12 ( 2 ) � ∙ 푆푆2 푚푚푚푚 (휆 ) − 휈 12 ( 2 ) ∙ 푆푆1 푚푎푎 (휆) = 푆푆 1−훽 2 푚푚푚푚 ( 휆 )
12 ( 2)푆푆1 푚푎푎 (휆 ) (5)
9.3.2.6 Ajuster par incrément la valeur de 휈 12 ( 2 ) et répéter 9.3.2.5 de sorte que la valeur moyenne de 푆푆2 푚푎푎 soit nulle sur la plage [휆1 ,휆2 ] Pour ce faire, utiliser un calcul formel de la valeur moyenne de la sensibilité spectrale corrigée, une exactitude suffisante étant toutefois souvent obtenue par un simple examen visuel (de la courbe de la sensibilité spectrale de la deuxième jonction) permettant de constater que la sensibilité spectrale moyenne semble s'approcher de zéro.
Correction de la sensibilité spectrale de la troisième jonction (pour le
9.3.3.1 Cette correction s'applique à la sensibilité spectrale de la jonction inférieure d'un dispositif PV à trois jonctions ou à la sensibilité spectrale de la troisième jonction d'un dispositif PV à quatre jonctions (voire plus) Pour corriger le couplage, les deux constantes
The values of $\nu_{12}(3)$ and $\nu_{23}(3)$ need to be determined Additionally, $SS2_{maa}(\lambda)$ must be established before proceeding, following the aforementioned procedure for correcting the spectral sensitivity of the second junction.
9.3.3.2 Identifier une plage de longueurs d'onde [흀 ퟏ 푻 ,흀 ퟐ 푻 ] dans la région de la sensibilité de la jonction supérieure, ó: a) la sensibilité spectrale de la jonction supérieure est proche de sa valeur maximale; b) la courbe de sensibilité spectrale est relativement lisse
9.3.3.3 Pour une longueur d'onde 흀ퟎ 푻 proche du milieu de la plage [흀ퟏ 푻 ,흀ퟐ 푻 ], calculer:
훽 12 ( 3 ) = 푆푆 푆푆 3 푚푚푚푚 ( 휆 0푇 )
1푚푎푎 ( 휆 0푇 ) (6)
9.3.3.4 Identifier une plage de longueurs d'onde [흀 ퟏ 푴 ,흀 ퟐ 푴 ] dans la région de la sensibilité de la jonction médiane, ó: a) la sensibilité spectrale de la jonction médiane est proche de sa valeur maximale; b) la courbe de sensibilité spectrale est relativement lisse
9.3.3.5 Pour une longueur d'onde 흀 ퟎ 푴 proche du milieu de la plage [흀 ퟏ 푴 ,흀 ퟐ 푴 ], calculer:
훽 23 ( 3 ) = 푆푆 푆푆 3 푚푚푚푚 ( 휆 0푀 )
2푚푎푎 ( 휆 0푀 ) (7)
9.3.3.6 Estimer le premier facteur de correction 흂 ퟏퟐ ( ퟑ ) :
9.3.3.7 Estimer le deuxième facteur de correction 흂 ퟐퟑ ( ퟑ ) :
9.3.3.8 Calculer la courbe 푺푺 ퟑ 풂풂풂 (흀) de la troisième jonction corrigée grâce à la formule (1 0) ci-dessous:
푆푆 3 푚푎푎 ( 휆) =�1 +휈 23 ( 3 ) +휈 12 ( 3 ) 휈 23 ( 3 ) � ∙ 푆푆 3 푚푚푚푚 ( 휆 ) − 휈 23 ( 3 ) ∙ 푆푆 2 푚푎푎 ( 휆 ) − 휈 12 ( 3 ) 휈 23 ( 3 ) ∙ 푆푆 1 푚푎푎 ( 휆 ) (1 0)
9.3.3.9 Ajuster par incrément les valeurs de 휈 12 ( 3 ) et 휈 23 ( 3 ) , et répéter 9.3.3.8 de sorte que la valeur moyenne de 푆푆3 푚푎푎 soit nulle sur les plages [휆1 푇 ,휆2 푇 ] et [휆1 푀 ,휆2 푀 ] Pour ce faire, utiliser comme précédemment un calcul formel des valeurs moyennes de la sensibilité spectrale corrigée, une exactitude suffisante étant toutefois souvent obtenue par un simple examen visuel permettant de constater que la sensibilité spectrale semble être nulle dans les deux plages de longueurs d'onde.
Correction de la sensibilité spectrale de la quatrième jonction (ou
The spectral sensitivity of the fourth junction (or upper junction) can be reasonably corrected by disregarding the effects of the upper junctions and focusing solely on the couplings from the two preceding junctions.
For the fourth junction, a) adjust the spectral sensitivity of the second and third junctions as outlined in sections 9.3.2 and 9.3.3 b) Repeat the procedure for the third junction, increasing both the lower and upper indices by 1.
La correction de la sensibilité spectrale des jonctions supérieures est une extension directe de cette procédure
Voir la bibliographie pour de plus amples informations
At the conclusion of the testing procedure, a certified report detailing the spectral sensitivity measurements must be prepared by the testing organization Each certificate or test report must include all elements required by IEC 60904-8 Additionally, the following elements must also be included and specified for each junction subjected to testing.
• Identification de la pseudolumière appliquée, y compris les longueurs d'onde, les bandes passantes et les éclairements;
• Description de la méthode adoptée pour déterminer la tension de polarisation;
• Tension de polarisation externe réellement appliquée;
• Documentation des corrections appliquées, le cas échéant;
• Déclaration de l'incertitude estimée de l'étalonnage ou des résultats d'essai applicables aux procédures de mesure des dispositifs multijonctions
M A Steiner, S R Kurtz, J F Geisz, W E McMahon and J M Olson, "Using phase effects to understand measurements of the quantum efficiency and related luminescent coupling in a multijunction solar cell", IEEE Journal of Photovoltaics, Vol 2, No 4, 201 2,pp 424-433
Myles A Steiner and colleagues conducted a study on measuring IV curves and subcell photovoltaic currents while considering luminescent coupling, published in the Journal of Photovoltaics.
M Meusel, R Adelhelm, F Dimroth, A.W Bett, and W Warta, Spectral Mismatch Correction and Spectrometric Characterization of Monolithic III-V Multi-Junction Solar Cells Progress in Photovoltaics: Research and Applications, 2002, 1 0(4): pp 243-255
G Siefer, C Baur, and A.W Bett, "External Quantum Efficiency Measurements of Germanium Bottom Subcells: Measurement Artifacts and Correction Procedures", Proceedings of the 35th IEEE Photovoltaic Specialists Conference, 201 0, Honolulu, HI pp 000704 – 07
Y Hishikawa, Y Tsuno, K Kurokawa, "Spectral response measurements of PV modules and multi-junction devices", Proceedings of 22 nd European Photovoltaics Solar Energy Conference, 2007, Milan, Italy, pp.2765-2769
Y Tsuno, Y Hishikawa, K Kurokawa, "A method for spectral response measurements of various PV modules", Proceedings of 23 rd European Photovoltaics Solar Energy Conference,
T Sogabe, A Ogura, C.-Y Hung, V Evstropov, M Mintairov, M Shvarts, Y Okada
"Experimental characterization and self-consistent modeling of luminescence coupling effect in III-V multijunction solar cells", Applied Physics Letters, 1 03, 263907, 201 3; doi: