| 1. |
- Bose, Sourav, et al.
(författare)
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Optical Lithography Patterning of SiO2 Layers for Interface Passivation of Thin Film Solar Cells
- 2018
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Ingår i: Solar RRL. - : Wiley. - 2367-198X. ; 2:12
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Tidskriftsartikel (refereegranskat)abstract
- Ultrathin Cu(In,Ga)Se-2 solar cells are a promising way to reduce costs and to increase the electrical performance of thin film solar cells. An optical lithography process that can produce sub-micrometer contacts in a SiO2 passivation layer at the CIGS rear contact is developed in this work. Furthermore, an optimization of the patterning dimensions reveals constrains over the features sizes. High passivation areas of the rear contact are needed to passivate the CIGS interface so that high performing solar cells can be obtained. However, these dimensions should not be achieved by using long distances between the contacts as they lead to poor electrical performance due to poor carrier extraction. This study expands the choice of passivation materials already known for ultrathin solar cells and its fabrication techniques.
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| 2. |
- Cunha, Jose M. V., et al.
(författare)
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High-Performance and Industrially Viable Nanostructured SiOx Layers for Interface Passivation in Thin Film Solar Cells
- 2021
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Ingår i: Solar RRL. - : John Wiley & Sons. - 2367-198X. ; 5:3
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Tidskriftsartikel (refereegranskat)abstract
- 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)Se-2 (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 degrees 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 (V-oc) and short-circuit current density (J(sc)) 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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| 3. |
- Lopes, Tomas S., et al.
(författare)
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Rear Optical Reflection and Passivation Using a Nanopatterned Metal/Dielectric Structure in Thin-Film Solar Cells
- 2019
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Ingår i: IEEE Journal of Photovoltaics. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2156-3381 .- 2156-3403. ; 9:5, s. 1421-1427
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Tidskriftsartikel (refereegranskat)abstract
- Currently, one of the main limitations in ultrathin Cu(In,Ga)Se-2 (CIGS) solar cells are the optical losses, since the absorber layer is thinner than the light optical path. Hence, light management, including rear optical reflection, and light trapping is needed. In this paper, we focus on increasing the rear optical reflection. For this, a novel structure based on having a metal interlayer in between the Mo rear contact and the rear passivation layer is presented. In total, eight different metallic interlayers are compared. For the whole series, the passivation layer is aluminum oxide (Al2O3). The interlayers are used to enhance the reflectivity of the rear contact and thereby increasing the amount of light reflected back into the absorber. In order to understand the effects of the interlayer in the solar cell performance both from optical and/or electrical point of view, optical simulations were performed together with fabrication and electrical measurements. Optical simulations results are compared with current density-voltage (J-V) behavior and external quantum efficiency measurements. A detailed comparison between all the interlayers is done, in order to identify the material with the greatest potential to he used as a rear reflective layer for ultrathin CIGS solar cells and to establish fabrication challenges. The Ti-W alloy is a promising a rear reflective layer since it provides solar cells with light to power conversion efficiency values of 9.9%, which is 2.2% (abs) higher than the passivated ultrathin sample and 3.7% (abs) higher than the unpassivated ultrathin reference sample.
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| 4. |
- Salome, Pedro M. P., et al.
(författare)
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Passivation of Interfaces in Thin Film Solar Cells : Understanding the Effects of a Nanostructured Rear Point Contact Layer
- 2018
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Ingår i: Advanced Materials Interfaces. - : Wiley. - 2196-7350. ; 5:2
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Tidskriftsartikel (refereegranskat)abstract
- Thin film solar cells based in Cu(In,Ga)Se-2 (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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| 5. |
- Vermang, Bart, et al.
(författare)
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Introduction of Si PERC Rear Contacting Designto Boost Efficiency of Cu(In,Ga)Se2 Solar Cells
- 2014
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Ingår i: IEEE Journal of Photovoltaics. - 2156-3381 .- 2156-3403. ; 4:6, s. 1644-1649
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Tidskriftsartikel (refereegranskat)abstract
- Recently, Cu(In,Ga)Se-2 (CIGS) solar cells have achieved 21% world-record efficiency, partly due to the introduction of a postdeposition potassium treatment to improve the front interface of CIGS absorber layers. However, as high-efficiency CIGS solar cells essentially require long diffusion lengths, the highly recombinative rear of these devices also deserves attention. In this paper, an Al2O3 rear surface passivation layer with nanosized local point contacts is studied to reduce recombination at the standard Mo/CIGS rear interface. First, passivation layers with well-controlled grids of nanosized point openings are established by use of electron beam lithography. Next, rear-passivated CIGS solar cells with 240-nm-thick absorber layers are fabricated as study devices. These cells show an increase in open-circuit voltage (+57 mV), short-circuit current (+3.8 mA/cm(2)), and fill factor [9.5% (abs.)], compared with corresponding unpassivated reference cells, mainly due to improvements in rear surface passivation and rear internal reflection. Finally, solar cell capacitance simulator (SCAPS) modeling is used to calculate the effect of reduced back contact recombination on high-efficiency solar cells with standard absorber layer thickness. The modeling shows that up to 50-mV increase in open-circuit voltage is anticipated.
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| 6. |
- Vermang, Bart, et al.
(författare)
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Rear surface optimization of CZTS solar cells by use of a passivation layer with nano-sized point openings
- 2015
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Ingår i: 2015 IEEE 42ND PHOTOVOLTAIC SPECIALIST CONFERENCE (PVSC). - 9781479979448
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Konferensbidrag (refereegranskat)abstract
- Previously, an innovative way to reduce rear interface recombination of Cu(In,Ga)(S,Se)(2) (CIGSSe) solar cells has been successfully developed. In this work, this concept is established in Cu-2(Zn,Sn)(S,Se)(4) (CZTSSe) cells, to demonstrate its potential for other thin-film technologies. Therefore, ultra-thin CZTS cells with an Al2O3 rear surface passivation layer having nano-sized point openings are fabricated. The results indicate that introducing such a passivation layer can have a positive impact on open circuit voltage (V-OC; +49%(rel.)) or short circuit current (J(SC); +17%(rel.)), compared to corresponding unpassivated cells. Hence, a promising efficiency improvement of 52%(rel.) is obtained for the rear passivated cells.
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| 7. |
- Vermang, Bart, et al.
(författare)
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Rear Surface Optimization of CZTS Solar Cells by Use of a Passivation Layer With Nanosized Point Openings
- 2016
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Ingår i: IEEE Journal of Photovoltaics. - 2156-3381 .- 2156-3403. ; 6:1, s. 332-336
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Tidskriftsartikel (refereegranskat)abstract
- Previously, an innovative way to reduce rear interface recombination in Cu(In, Ga)(S, Se)(2) (CIGSSe) solar cells has been successfully developed. In this work, this concept is established in Cu-2(Zn, Sn)(S, Se)(4) (CZTSSe) cells to demonstrate its potential for other thin-film technologies. Therefore, ultrathin CZTS cells with an Al2O3 rear surface passivation layer having nanosized point openings are fabricated. The results indicate that introducing such a passivation layer can have a positive impact on open-circuit voltage (V-OC; +17% rel.), short-circuit current (J(SC); +5% rel.), and fill factor (FF; +9% rel.), compared with corresponding unpassivated cells. Hence, a promising efficiency improvement of 32% rel. is obtained for the rear passivated cells.
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| 8. |
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