Lithographic fabrication of point contact with Al2O3 rear-surface-passivated and ultra-thin Cu(In,Ga)Se2 solar cells

Choi, Seongim; Kamikawa, Yukiko; Nishinaga, Jiro; Yamada, A.; Shibata, Hajime; Niki, Shigeru

doi:10.1016/j.tsf.2018.08.044

Cited by 20 publications

(28 citation statements)

References 19 publications

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“…For the thickest CIGS absorber layer, i.e., 1.89 µm, the difference between passivated and reference devices are hardly noticeable for Voc and Jsc, but there is still an improvement [16]. On the other hand, for the thinnest CIGS absorber layer, i.e., 240 nm, there are clear improvements in both Voc and Jsc, as expected [18].…”

Section: Solar Simulator Resultssupporting

confidence: 60%

“…To conclude, remarkable progress has been made in creating dielectric-based rear contact passivation strategies for CIGS solar cells. A cell efficiency of 18.1% has been achieved with the conventional, i.e., 1.89 µm thick absorber layer, CIGS solar cell which has a 5 nm thick atomic-layer-deposited Al 2 O 3 passivation layer with contact openings realized with photo-lithography [16]. For ultra-thin, i.e., 0.4 µm thick absorber layer, CIGS solar cells, the highest efficiency value, 13.5%, was realized in [14].…”

Section: Discussionmentioning

confidence: 99%

“…There is also a more technologically viable technique to create these layers, which is DC sputtering. DC After the creation of the passivation layer, the thickness of this layer was determined using high angle annular dark-field (HAADF) transmission electron microscopy (TEM) in [9], spectrally resolved ellipsometry in [12,13,16,17,24,25], TEM in [14,18], energy dispersive X-ray spectroscopy (EDX) in [15], scanning electron microscopy (SEM) in [11,19,20,22], profilometry in [5], and atomic force microscopy (AFM) in [23]. The thickness of the passivation layer should be chosen to be sufficiently thin (~1-2 nm) to allow tunneling if there is no contact opening approach applied to this layer.…”

Section: Dielectric-based Passivation Layersmentioning

confidence: 99%

“…To generate the contact openings in the Al 2 O 3 passivation layer, advanced techniques such as e-beam, nano-imprint, nano-sphere, or photolithography were used in the following studies [5,9,11,[16][17][18]22,23]. Lithography is one of the most advanced techniques that is used for this purpose.…”

Section: Contacting Approachmentioning

confidence: 99%

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Dielectric-Based Rear Surface Passivation Approaches for Cu(In,Ga)Se2 Solar Cells—A Review

et al. 2019

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This review summarizes all studies which used dielectric-based materials as a passivation layer at the rear surface of copper indium gallium (di)selenide, Cu(In,Ga)Se2, (CIGS)-based thin film solar cells, up to 2019. The results regarding the kind of dielectric materials, the deposition techniques, contacting approaches, the existence of additional treatments, and current–voltage characteristics (J–V) of passivated devices are emphasized by a detailed table. The techniques used to implement the passivation layer, the contacting approach for the realization of the current flow between rear contact and absorber layer, additional light management techniques if applicable, the solar simulator results, and further characterization techniques, i.e., external quantum efficiency (EQE) and photoluminescence (PL), are shared and discussed. Three graphs show the difference between the reference and passivated devices in terms of open-circuit voltage (Voc), short-circuit current (Jsc), and efficiency (η), with respect to the thicknesses of the absorber layer. The effects of the passivation layer at the rear surface are discussed based on these three graphs. Furthermore, an additional section is dedicated to the theoretical aspects of the passivation mechanism.

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Section: Solar Simulator Resultssupporting

confidence: 60%

Section: Discussionmentioning

confidence: 99%

Section: Dielectric-based Passivation Layersmentioning

confidence: 99%

Section: Contacting Approachmentioning

confidence: 99%

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Dielectric-Based Rear Surface Passivation Approaches for Cu(In,Ga)Se2 Solar Cells—A Review

et al. 2019

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“…To mitigate the effect of reduced voltage, efficient surface passivation has to be ensured. Thin passivation layers, such as Al2O3 have been applied to the rear CIGS/Mo interface [11][12][13][14]. To compensate for reduced photocurrent, an additional treatment to increase light absorption in the thin absorber needs to be carried out.…”

Section: Introductionmentioning

confidence: 99%

Light management design in ultra-thin chalcopyrite photovoltaic devices by employing optical modelling

Kovačič

Krč

Lipovšek

et al. 2019

Solar Energy Materials and Solar Cells

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In ultra-thin chalcopyrite solar cells and photovoltaic modules, efficient light management is required to increase the photocurrent and to gain in conversion efficiency. In this work we employ optical modelling to investigate different optical approaches and quantify their potential improvements in the short-circuit current density of Cu(In, Ga)Se2 (CIGS) devices. For structures with an ultra-thin (500 nm) CIGS absorber, we study the improvements related to the introduction of (i) highly reflective metal back reflectors, (ii) internal nano-textures applied to the substrate and (iii) external micro-textures by using a light management foil. In the analysis we use CIGS devices in a PV module configuration, thus, solar cell structure including encapsulation and front glass. A thin Al2O3 layer was considered in the structure at the rear side of CIGS for passivation and diffusion barrier for metal reflectors. We show that not any individual aforementioned approach is sufficient to compensate for the short circuit drop related to ultra-thin absorber, but a combination of a highly reflective back contact and textures (internal or external) is needed to obtain and also exceed the short-circuit current density of a thick (1800 nm) CIGS absorber.

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Over 100 mV V_OC Improvement for Rear Passivated ACIGS Ultra‐Thin Solar Cells

Oliveira

Curado

Teixeira

et al. 2023

Adv Funct Materials

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A decentralized energy system requires photovoltaic solutions to meet new aesthetic paradigms, such as lightness, flexibility, and new form factors. Notwithstanding, the materials shortage in the Green Transition is a concern gaining momentum due to their foreseen continuous demand. A fruitful strategy to shrink the absorber thickness, meeting aesthetic and shortage materials consumption targets, arises from interface passivation. However, a deep understanding of passivated systems is required to close the efficiency gap between ultra‐thin and thin film devices, and to mono‐Si. Herein, a (Ag,Cu)(In,Ga)Se2 ultra‐thin solar cell, with 92% passivated rear interface area, is compared with a conventional nonpassivated counterpart. A thin MoSe2 layer, for a quasi‐ohmic contact, is present in the two architectures at the contacts, despite the passivated device narrow line scheme. The devices present striking differences in charge carrier dynamics. Electrical and optoelectronic analysis combined with SCAPS modelling suggest a lower recombination rate for the passivated device, through a reduction on the rear surface recombination velocity and overall defects, comparing with the reference solar cell. The new architecture allows for a 2% efficiency improvement on a 640 nm ultra‐thin device, from 11% to 13%, stemming from an open circuit voltage increase of 108 mV.

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Lithographic fabrication of point contact with Al2O3 rear-surface-passivated and ultra-thin Cu(In,Ga)Se2 solar cells

Cited by 20 publications

References 19 publications

Dielectric-Based Rear Surface Passivation Approaches for Cu(In,Ga)Se2 Solar Cells—A Review

Dielectric-Based Rear Surface Passivation Approaches for Cu(In,Ga)Se2 Solar Cells—A Review

Light management design in ultra-thin chalcopyrite photovoltaic devices by employing optical modelling

Over 100 mV V_OC Improvement for Rear Passivated ACIGS Ultra‐Thin Solar Cells

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Lithographic fabrication of point contact with Al2O3 rear-surface-passivated and ultra-thin Cu(In,Ga)Se2 solar cells

Cited by 20 publications

References 19 publications

Dielectric-Based Rear Surface Passivation Approaches for Cu(In,Ga)Se2 Solar Cells—A Review

Dielectric-Based Rear Surface Passivation Approaches for Cu(In,Ga)Se2 Solar Cells—A Review

Light management design in ultra-thin chalcopyrite photovoltaic devices by employing optical modelling

Over 100 mV VOC Improvement for Rear Passivated ACIGS Ultra‐Thin Solar Cells

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Product

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Over 100 mV V_OC Improvement for Rear Passivated ACIGS Ultra‐Thin Solar Cells