Understanding the AC Equivalent Circuit Response of Ultrathin Cu(In,Ga)Se<sub>2</sub>Solar Cells

Cunha, José M. V.; Rocha, Cátia Vieira; Vinhais, Carlos; Fernandes, Paulo A.; Salomé, Pedro M. P.

doi:10.1109/jphotov.2019.2927918

Cited by 16 publications

(27 citation statements)

References 51 publications

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“…We note that both in p-n junctions and in MIS devices, such Cd is expected [72]. In the previous node in parallel, a capacitance C1 and a resistance R1 in series is present, which may correspond to CIGS defects localized on the quasi-neutral region [71,75,76]. Taking into account the Cd capacitance values of the Al2O350 and Al2O3250 samples, and comparing them with Ref and Al2O3/CdS, the Al2O3 samples show a higher Cd value, indicating a thinner CIGS depletion region, which is expected since there is no formation of a typical pn junction.…”

Section: Optoelectronic Characterizationmentioning

confidence: 85%

“…C-G-f measurements were performed in order to test different equivalent circuits of the ac response of the devices by performing a fitting to the measured data. A detailed description to select the most suitable circuit for each sample is described elsewhere [71]. All the samples demonstrate the same equivalent circuit (Fig.…”

Section: Optoelectronic Characterizationmentioning

confidence: 99%

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Front passivation of Cu(In,Ga)Se2 solar cells using Al2O3: Culprits and benefits

Curado

Teixeira

Monteiro

et al. 2020

Applied Materials Today

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In recent years, the strategies used to break the Cu(In,Ga)Se2 (CIGS) world record of light to power conversion efficiency, were based on improvements of the absorber optoelectronic and crystalline properties, mainly using complex post-deposition treatments. To reach even higher efficiency values, advances in the solar cell architecture are needed focusing in the CIGS interfaces. In this study, we evaluate the structural, morphological and optoelectronic impact on the CIGS properties of using an Al2O3 layer as a potential front passivation layer. The impact of Al2O3 tunnelling layer between CIGS and CdS is also addressed in this study. Morphological and structural analyses reveal that the use of Al2O3 alone is not detrimental to CIGS, although it does not resist to the CdS chemical bath deposition. When CdS is deposited on top of Al2O3, the CIGS optoelectronic properties are heavily degraded. Nonetheless, when Al2O3 is used alone, optoelectronic measurements reveal a positive impact of its inclusion such as a very low concentration of interface defects and the CIGS keeping the same recombination channels. With the findings of this study the best use of Al2O3 front passivation layer could be with alternative buffer layers. The Al2O3 layer will keep the CIGS surface with a low density of defects while keeping its structural and optoelectronic properties as good as the ones when CdS is deposited. It can also be reported that a comparison between the different analyses allowed us to strongly suggest for the first time that low-energy muon spin spectroscopy (LE-μSR) is sensitive to both charge carrier separation and bulk recombination in complex semiconductors.

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Section: Optoelectronic Characterizationmentioning

confidence: 85%

Section: Optoelectronic Characterizationmentioning

confidence: 99%

Front passivation of Cu(In,Ga)Se2 solar cells using Al2O3: Culprits and benefits

Curado

Teixeira

Monteiro

et al. 2020

Applied Materials Today

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“…To better understand the Na concentration influence together with the SiO x passivation effect on each device's optoelectronic properties, dark capacitance versus voltage ( C – V ) measurements were conducted to get the net free carriers concentration ( N cv ) and depletion region width ( W ) values for each device at the 0 V bias. [ 33,66,67 ] A representative N cv against W plot, with varying bias, for each device, is shown in Figure 2b with the N cv and W average and standard deviation values shown in the inset table of Figure 2b. It is noted that the shown plot for each device is a representative curve, which might have different N cv and W values compared with the respective average values presented in the inset table.…”

Section: Characterizationmentioning

confidence: 99%

“…Several insulator materials, e.g., Al 2 O 3 , Si 3 N x , SiO x , TiO 2 , to name but a few, have been studied as passivation layers in the CIGS technology. [ 20,25,30-33 ] The prospect of using the same approach and insulator to passivate both front and rear interfaces of the same solar cell is very attractive from a fabrication perspective, and SiO x emerges as a strong material to perform such role. [ 20,30,34 ] SiO x presents promising properties that allow for its implementation as front and rear passivation layers, namely, the ability to change the polarity values of the fixed insulator charges ( Q f ) by manipulating the deposition parameters, enabling an efficient field‐effect passivation of both minority and majority CIGS charge carriers.…”

Section: Introductionmentioning

confidence: 99%

High‐Performance and Industrially Viable Nanostructured SiO_x Layers for Interface Passivation in Thin Film Solar Cells

et al. 2021

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Herein, it is demonstrated, by using industrial techniques, that a passivation layer with nanocontacts based on silicon oxide (SiOx) leads to significant improvements in the optoelectronical performance of ultrathin Cu(In,Ga)Se2 (CIGS) solar cells. Two approaches are applied for contact patterning of the passivation layer: point contacts and line contacts. For two CIGS growth conditions, 550 and 500 °C, the SiOx passivation layer demonstrates positive passivation properties, which are supported by electrical simulations. Such positive effects lead to an increase in the light to power conversion efficiency value of 2.6% (absolute value) for passivated devices compared with a nonpassivated reference device. Strikingly, both passivation architectures present similar efficiency values. However, there is a trade‐off between passivation effect and charge extraction, as demonstrated by the trade‐off between open‐circuit voltage (Voc) and short‐circuit current density (Jsc) compared with fill factor (FF). For the first time, a fully industrial upscalable process combining SiOx as rear passivation layer deposited by chemical vapor deposition, with photolithography for line contacts, yields promising results toward high‐performance and low‐cost ultrathin CIGS solar cells with champion devices reaching efficiency values of 12%, demonstrating the potential of SiOx as a passivation material for energy conversion devices.

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“…Absorber layers of Cu(In,Ga)Se2 (CIGS) with submicrometer thicknesses, or ultrathin absorbers, are decidedly motivated thin film solar cells research topics. In addition to a lower bill of materials due to its usage reduction, the bulk recombination rate within the CIGS absorber layer may also decrease [1]- [3]. With these two potential benefits, research has been focused on solving the two principal problems that the use of ultrathin devices entail: i) augmented rear interface recombination at the Mo/CIGS interface, and ii) abridged photo-generation due to the width for full absorption being effectively larger than the absorber thickness.…”

Section: Introductionmentioning

confidence: 99%

Decoupling of Optical and Electrical Properties of Rear Contact CIGS Solar Cells

Cunha

Fernandes

Salomé

et al. 2019

IEEE J. Photovoltaics

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A novel architecture that comprises rear interface passivation and increased rear optical reflection is presented with the following advantages: i) an enhanced optical reflection is achieved by depositing a metallic layer over the Mo rear contact; ii) the addition of a sputtered Al2O3 layer improves the interface quality with CIGS; and, iii) the rear-openings are refilled with Mo to maintain the optimal ohmic electrical contact as generally observed from the growth of CIGS on Mo. Hence, a decoupling between the electrical function and the optical function of the substrate is achieved. We present in detail the manufacturing procedure of such type of architectures together with its benefits and caveats. A preliminary electrical analysis of resulting solar cells showing a proof-of-concept of the architecture is presented and discussed.

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Understanding the AC Equivalent Circuit Response of Ultrathin Cu(In,Ga)Se₂Solar Cells

Abstract: Access to the published version may require subscription. N.B. When citing this work, cite the original published paper.

Cited by 16 publications

References 51 publications

Front passivation of Cu(In,Ga)Se2 solar cells using Al2O3: Culprits and benefits

Front passivation of Cu(In,Ga)Se2 solar cells using Al2O3: Culprits and benefits

High‐Performance and Industrially Viable Nanostructured SiO_x Layers for Interface Passivation in Thin Film Solar Cells

Decoupling of Optical and Electrical Properties of Rear Contact CIGS Solar Cells

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Understanding the AC Equivalent Circuit Response of Ultrathin Cu(In,Ga)Se2Solar Cells

Abstract: Access to the published version may require subscription. N.B. When citing this work, cite the original published paper.

Cited by 16 publications

References 51 publications

Front passivation of Cu(In,Ga)Se2 solar cells using Al2O3: Culprits and benefits

Front passivation of Cu(In,Ga)Se2 solar cells using Al2O3: Culprits and benefits

High‐Performance and Industrially Viable Nanostructured SiOx Layers for Interface Passivation in Thin Film Solar Cells

Decoupling of Optical and Electrical Properties of Rear Contact CIGS Solar Cells

Contact Info

Product

Resources

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Understanding the AC Equivalent Circuit Response of Ultrathin Cu(In,Ga)Se₂Solar Cells

High‐Performance and Industrially Viable Nanostructured SiO_x Layers for Interface Passivation in Thin Film Solar Cells