Imaging photocurrent collection losses in solar cells

Huhn, Vito; Pieters, Bart E.; Augarten, Y.; Gerber, Andreas; Hinken, David; Rau, Uwe

doi:10.1063/1.4971266

Cited by 9 publications

(7 citation statements)

References 13 publications

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“…Meanwhile, the simulated f T – V curves of the correlated areas in Figure d extracted from the network model are shown in Figure (solid lines). We can observe that the locally averaged f T values decrease with increasing applied voltage, which is caused by a decrease in the diode resistance compared to the series resistance within the cell . It is also evident that a transition voltage V b can be observed at the crossover point between the nonshunted and ohmic shunted areas.…”

Section: Resultsmentioning

confidence: 80%

Spatially Resolved Identification of Shunt Defects in Thin Film Solar Cells via Current Transport Efficiency Imaging Combined with 3D Finite Element Modeling

Ren

Zhang

et al. 2019

Solar RRL

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Inhomogeneously distributed shunt defects significantly reduce the performance of thin film solar cells. The existing uses of simple equivalent circuit models and lumped cell-level parameters are insufficient to understand the behaviors of different shunting types. This study demonstrates how the reciprocity theorem, which bridges the relationship between the terminal differential changes and local responses of a solar cell, for the current transport efficiency can be used to spatially identify ohmic and nonohmic shunt defects exemplified in CdTe solar cells. Differential electroluminescence imaging and three-dimensional finite element modeling are used to determine the current transport efficiency images. Due to the specific local differential conductance behaviors, the application of current transport efficiency imaging for the detailed analysis of different shunt defects is successfully verified in both experimental and simulation methods. In addition, the influences of two types of shunt defects on the electrical potentials and current flow of a cell are discussed. The modeling results indicate that a nonohmic shunt defect with a larger junction voltage dip and leakage current is more detrimental than an ohmic shunt defect within the cell.

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Section: Resultsmentioning

confidence: 80%

Spatially Resolved Identification of Shunt Defects in Thin Film Solar Cells via Current Transport Efficiency Imaging Combined with 3D Finite Element Modeling

Ren

Zhang

et al. 2019

Solar RRL

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“…Therefore, δI L (x,y)S is equal to δI * T;sc ; the terminal current increment at short circuit. The validation of this assumption has been observed on silicon cells under roughly 2 suns, 24 GaAs cells up to 47 suns, 10 and CdTe cells at 1.5 suns. 8 We note that these may not always be the case, for example when illumination is too high in Huhn et al 24 f t drops due to lateral current transport depending on the illumination intensities, dark currents, and sheet resistances.…”

Section: Methodsmentioning

confidence: 80%

“…The validation of this assumption has been observed on silicon cells under roughly 2 suns, GaAs cells up to 47 suns, and CdTe cells at 1.5 suns . We note that these may not always be the case, for example when illumination is too high in Huhn et al

{\overset{true¯}{f}}_{t}

drops due to lateral current transport depending on the illumination intensities, dark currents, and sheet resistances. For less ideal cells or under higher illumination, those quantities can be solved by a nonlinear differential equation to verify the assumption.…”

Section: Methodsmentioning

confidence: 99%

Current transport efficiency analysis of multijunction solar cells by luminescence imaging

Delamarre

Jeco

et al. 2019

Progress in Photovoltaics

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Multijunction solar cells are currently leading in efficiency among all types of solar cells. However, the efficiency of those cells under concentrated illumination is limited by the trade‐off between shadowing by the contact grid and series resistances. In this paper, we provide a method using luminescence to image the current transport efficiency for a precise and rapid measurement of the resistance effect. Light beam induced current (LBIC) measurement is used for the first time to calculate current transport efficiency in comparison with that of the luminescence method. Profiles of transport efficiency in both means are in good agreement. Furthermore, a quasi‐3‐D simulation using SPICE is used to explain the transport efficiency image. We find that the carrier transport efficiency distribution is primarily influenced by the perimeter recombination of the middle cell.

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“…4b) 15 , which shows a homogeneous diode voltage distribution with a fluctuation of about 1 mV. No obvious diode voltage change between the fingers is observed indicating a good lateral conductance without TCO [16][17][18] . Fig.…”

Section: ωCmmentioning

confidence: 95%

Transparent-Conductive-Oxide-Free Front Contacts for High Efficiency Silicon Heterojunction Solar Cells

Pomaska

Lambertz

et al. 2020

Preprint

Self Cite

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In order to compensate the insufficient conductance of heterojunction thin films, transparent conductive oxides (TCO) have been used for decades in both-sides contacted crystalline silicon heterojunction (SHJ) solar cells to provide lateral conduction for efficient carrier collection. In this work, we substitute the TCO layers by utilizing the lateral conduction of c-Si absorber, thereby enabling a TCO-free design. A series resistance of 0.32 Ωcm2 and a fill factor of 80.7% were measured for a TCO-free back-junction SHJ solar cell with a conventional finger pitch of 1.8 mm, thereby proving that relying on lateral conduction in the c-Si bulk is compatible with low series resistances. Achieving high efficiencies in SHJ solar cells with TCO-free front contacts requires suppressing deterioration of the passivation quality induced by direct metal-a-Si:H contacts and in-diffusion of metal into the a-Si:H layer. We show that an ozone treatment at the a-Si:H/metal interface suppresses the metal diffusion and improves the passivation without increasing the contact resistivity. SHJ solar cells with TCO-free front contacts and ozone treatment achieve efficiencies of > 22%.

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Imaging photocurrent collection losses in solar cells

Cited by 9 publications

References 13 publications

Spatially Resolved Identification of Shunt Defects in Thin Film Solar Cells via Current Transport Efficiency Imaging Combined with 3D Finite Element Modeling

Spatially Resolved Identification of Shunt Defects in Thin Film Solar Cells via Current Transport Efficiency Imaging Combined with 3D Finite Element Modeling

Current transport efficiency analysis of multijunction solar cells by luminescence imaging

Transparent-Conductive-Oxide-Free Front Contacts for High Efficiency Silicon Heterojunction Solar Cells

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