Copper–indium–gallium–selenide (CIGS) solar cells with localized back contacts for achieving high performance

Nerat, Marko

doi:10.1016/j.solmat.2012.05.020

Cited by 24 publications

(11 citation statements)

References 25 publications

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“…This emphasizes that main parameter describing the influence of the PL is the band bending it induces. Given that Π > 95%, the electric field generated by the PL will also repel the holes from the contact area, as it happens for PERL in ultra-thin films [14]. In fact, we already noticed that lim α→0 ϕ C = ϕ P L .…”

Section: Discussionmentioning

confidence: 83%

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Point contacts at the copper-indium-gallium-selenide interface—A theoretical outlook

Bercegol

Chacko

Lauermann

et al. 2016

Journal of Applied Physics

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For a long time, it has been assumed that recombination in the space-charge region of CIGS is dominant, at least in high efficiency solar cells with low band gap. The recent developments like KF post deposition treatment and point-contact junction may call this into question. In this work a theoretical outlook is made using three-dimensional simulations to investigate the effect of pointcontact openings through a passivation layer on CIGS solar cell performance. A large set of solar cells is modeled under different scenarios for the charged defect levels and density, radius of the openings, interface quality and conduction band offset. The positive surface charge created by the passivation layer induces band bending and this influences the contact (CdS) properties, making it beneficial for the open circuit voltage and efficiency, and the effect is even more pronounced when coverage area is more than 95 %, and also makes a positive impact on the device performance, even in the presence of a spike at CIGS/CdS heterojunction.

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Section: Discussionmentioning

confidence: 83%

“…In any case, Π should remain under 99% to avoid fill factor loss. In the simulations presented here, a distance between point contacts that remained in the same order of magnitude as the electron diffusion length was used (2β = 1µm), which is also highly important for the efficiency of a point-contacted structure [14].…”

Section: Discussionmentioning

confidence: 99%

Point contacts at the copper-indium-gallium-selenide interface—A theoretical outlook

Bercegol

Chacko

Lauermann

et al. 2016

Journal of Applied Physics

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“…Simply, the chemical passivation allows for the decrease of the total number of electrically active defects. [38][39][40][41] Ultrathin devices have recently been studied in detail by numerous groups [42][43][44][45][46][47] as they have the potential to reduce the material costs and manufacturing times. Such field is beneficial for the electrical performance of the solar cell, since it drives minority carriers away from the highly recombinative rear contact into the space charge region.…”

Section: Introductionmentioning

confidence: 99%

“…[36,37] These findings have motivated device simulations that have predicted gains up to 3% (in absolute power conversion efficiency) in fully passivated solar cells. [38][39][40][41] Ultrathin devices have recently been studied in detail by numerous groups [42][43][44][45][46][47] as they have the potential to reduce the material costs and manufacturing times. [48] Ultrathin devices are believed to be the forward path in this CIGS technology as they enable a combination of significant advantages: (i) lower material consumption, which is of crucial industrial importance mainly due to In scarcity; (ii) increased mechanical flexibility and integration in a broad range of consumer-oriented applications (e.g., BIPV, portable electronics, wearables, internet of things, etc.…”

Section: Introductionmentioning

confidence: 99%

Passivation of Interfaces in Thin Film Solar Cells: Understanding the Effects of a Nanostructured Rear Point Contact Layer

Salomé

Vermang

Ribeiro‐Andrade

et al. 2017

Adv Materials Inter

110

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Thin film solar cells based in Cu(In,Ga)Se2 (CIGS) are among the most efficient polycrystalline solar cells, surpassing CdTe and even polycrystalline silicon solar cells. For further developments, the CIGS technology has to start incorporating different solar cell architectures and strategies that allow for very low interface recombination. In this work, ultrathin 350 nm CIGS solar cells with a rear interface passivation strategy are studied and characterized. The rear passivation is achieved using an Al2O3 nanopatterned point structure. Using the cell results, photoluminescence measurements, and detailed optical simulations based on the experimental results, it is shown that by including the nanopatterned point contact structure, the interface defect concentration lowers, which ultimately leads to an increase of solar cell electrical performance mostly by increase of the open circuit voltage. Gains to the short circuit current are distributed between an increased rear optical reflection and also due to electrical effects. The approach of mixing several techniques allows us to make a discussion considering the different passivation gains, which has not been done in detail in previous works. A solar cell with a nanopatterned rear contact and a 350 nm thick CIGS absorber provides an average power conversion efficiency close to 10%.

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“…Vermang et al introduced these concepts for electrical passivation to ultra‐thin CIGS cells and used nano‐sized point contacts, up to a few microns spaced apart. Nerat optoelectrically simulated various 1D localized back contact designs for 2 µm thick CIGS cells. According to this work, a periodicity up to 100 µm should still increase the cell's performance (at 80% back contact coverage).…”

Section: Introductionmentioning

confidence: 99%

Optoelectrical improvement of ultra‐thin Cu(In,Ga)Se₂ solar cells through microstructured MgF₂ and Al₂O₃ back contact passivation layer

Casper

Hünig

Gomard

et al. 2016

Physica Rapid Research Ltrs

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Decreasing the absorber layer thickness of thin‐film solar cells can be an effective solution for cost reduction of photovoltaic electricity generation. Unfortunately, this reduction leads to detrimental effects such as incomplete photon absorption and increased charge carrier recombination at the rear electrode. To tackle these losses in ultra‐thin 0.5 µm Cu(In,Ga)Se2 (CIGS) solar cells, we developed different passivation structures made of MgF2 and Al2O3 at the molybdenum–CIGS interface, leading to localized back contacts. The influence of the distance between those contacts on the cell performance was studied by varying the periodicity of the applied 1D patterns from 6 μm to 30 μm. Thus, an increase in performance was measured for microstructured layers with a periodicity of up to 12 µm. More precisely, a MgF2 layer yielded an increase in power conversion efficiency (PCE) of up to 9%rel compared to an unpassivated cell design, and a passivation layer comprising Al2O3 led to up to a 5%rel increase in PCE. The gains were primarily attributed to an increased reflectivity of the back contact, while the formation of a negative backside field in the case of Al2O3 might have contributed to this increase by preventing electrons from recombining at the backside interface. Our findings indicate a high lateral conductivity for holes inside the multicrystalline CIGS compound over few tens of micrometres, which allows an independent design of future back contacts and light‐trapping schemes.

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Copper–indium–gallium–selenide (CIGS) solar cells with localized back contacts for achieving high performance

Cited by 24 publications

References 25 publications

Point contacts at the copper-indium-gallium-selenide interface—A theoretical outlook

Point contacts at the copper-indium-gallium-selenide interface—A theoretical outlook

Passivation of Interfaces in Thin Film Solar Cells: Understanding the Effects of a Nanostructured Rear Point Contact Layer

Optoelectrical improvement of ultra‐thin Cu(In,Ga)Se₂ solar cells through microstructured MgF₂ and Al₂O₃ back contact passivation layer

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Copper–indium–gallium–selenide (CIGS) solar cells with localized back contacts for achieving high performance

Cited by 24 publications

References 25 publications

Point contacts at the copper-indium-gallium-selenide interface—A theoretical outlook

Point contacts at the copper-indium-gallium-selenide interface—A theoretical outlook

Passivation of Interfaces in Thin Film Solar Cells: Understanding the Effects of a Nanostructured Rear Point Contact Layer

Optoelectrical improvement of ultra‐thin Cu(In,Ga)Se2 solar cells through microstructured MgF2 and Al2O3 back contact passivation layer

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Product

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About

Optoelectrical improvement of ultra‐thin Cu(In,Ga)Se₂ solar cells through microstructured MgF₂ and Al₂O₃ back contact passivation layer