| 1. |
- Birant, Gizem, et al.
(författare)
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Rear surface passivation of ultra-thin CIGS solar cells using atomic layer deposited HfOx
- 2020
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Ingår i: EPJ Photovoltaics. - : EDP Sciences. - 2105-0716. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- In this work, hafnium oxide layer is investigated as rear surface passivation layer for ultra-thin (550 nm) CIGS solar cells. Point contact openings in the passivation layer are realized by spin-coating potassium fluoride prior to absorber layer growth. Contacts are formed during absorber layer growth and visualized with scanning electron microscopy (SEM). To assess the passivating qualities, HfOx was applied in a metal-insulator-semiconductor (MIS) structure, and it demonstrates a low interface trap density in combination with a negative density of charges. Since we used ultra-thin devices that are ideal to probe improvements at the rear, solar cell results indicated improvements in all cell parameters by the addition of 2 nm thick HfOx passivation layer with contact openings.
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| 2. |
- 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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| 3. |
- Edoff, Marika, 1965-, et al.
(författare)
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Back Contact Passivation Effects in Bi-Facial Thin CIGS Solar Cells
- 2016
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Ingår i: 2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC). - : IEEE. - 9781509027248 ; , s. 3527-3529
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Konferensbidrag (refereegranskat)abstract
- Bi-facial solar cells with ultrathin CIGS solar cells are fabricated to investigate the influence of back contact passivation. Solar cells with CIGS thicknesses of 300 and 500 nm and with an ultrathin transparent Mo layer are characterized using EQE measurements from both the front and the rear side as well as with I-V measurements. Back contact passivation consisting of Al2O3 deposited by atomic layer deposition and nano-sized point contact openings is used. The results are compared to cells with only the transparent Mo layer as back contact. We find a significant effect of the passivation manifested as an increase in the current density of the solar cells with the passivation.
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| 4. |
- Edoff, Marika, 1965-, et al.
(författare)
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Ultrathin CIGS Solar Cells with Passivated and Highly Reflective Back Contacts – : Results from the ARCIGS-M Consortium
- 2019
-
Ingår i: Proceedings of 36th European Photovoltaic Solar Energy Conference and Exhibition. ; , s. 597-600
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this work, we report results from the EU-funded project ARCIGS-M. The project started in 2016 and aims to reduce the use of indium and gallium by enabling the use of very thin Cu(In,Ga)Se2 (CIGS) layers while retaining high efficiency and developing innovative low-cost steel substrates as alternatives to glass. In the project, reflective layers containing TCO´s and silver have successfully been used to enhance the reflective properties of the rear contact. In addition, passivation layers based on alumina (Al2O3) deposited by atomic layer deposition (ALD) have been found to yield good passivation of the rear contact. Since the alumina layers are dielectric, perforation of these layers is necessary to provide adequate contacting. The design of the perforation patterns has been investigated by a combination of modeling and experimental verification by electron beam lithography. In parallel a nano-imprint lithography (NIL) process is further developed for scale-up and application in prototype modules. Advanced optoelectrical characterization supported by modeling is used to fill in the missing gaps in optical and electrical properties, regarding CIGS, interfaces and back contact materials.
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| 5. |
- Fjällström, Viktor, et al.
(författare)
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Recovery After Potential-Induced Degradation of CuIn1-xGaxSe2 Solar Cells With CdS and Zn(O,S) Buffer Layers
- 2015
-
Ingår i: IEEE Journal of Photovoltaics. - 2156-3381 .- 2156-3403. ; 5:2, s. 664-669
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Tidskriftsartikel (refereegranskat)abstract
- This study deals with potential-induced degradation (PID) of Cu(In,Ga)Se-2-based solar cells and different approaches to subsequent recovery of efficiency. Three different recovery methods were studied: 1) etch recovery, 2) accelerated recovery, and 3) unaccelerated recovery. After being completely degraded, the solar cells with CdS buffer layers recovered their efficiencies at different rates, depending on the method which was used. On the other hand, if Zn(O,S) was used as a buffer layer instead of CdS, the recovery rate was close to zero. The buffer layer type clearly influenced the sodium distribution during PID stressing and recovery, as well as the possibilities for recovery of the electrical performance.
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| 6. |
- Joel, Jonathan, et al.
(författare)
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On the assessment of CIGS surface passivation by photoluminescence
- 2015
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Ingår i: Physica Status Solidi. Rapid Research Letters. - : Wiley. - 1862-6254 .- 1862-6270. ; 9:5, s. 288-292
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Tidskriftsartikel (refereegranskat)abstract
- An optimized test structure to study rear surface passivation in Cu(In,Ga)Se-2 (CIGS) solar cells by means of photoluminescence (PL) is developed and tested. The structure - illustrated in the abstract figure - is examined from the rear side. To enable such rear PL assessment, a semi-transparent ultrathin Mo layer has been developed and integrated in place of the normal rear contact. The main advantages of this approach are (i) a simplified representation of a rear surface passivated CIGS solar cell is possible, (ii) it is possible to assess PL responses originating close to the probed rear surface, and (iii) a stable PL response as a function of air exposure time is obtained. In this work, PL measurements of such structures with and without rear surface passivation layers have been compared, and the measured improvement in PL intensity for the passivated structures is associated with enhanced CIGS rear interface properties. [GRAPHICS] Transmission electron microscope (TEM) bright field cross-section image of the rear illuminated test structure fabricated for PL characterization.
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| 7. |
- Kotipalli, Ratan, et al.
(författare)
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Addressing the impact of rear surface passivation mechanisms on ultra-thin Cu(In,Ga)Se2 solar cell performances using SCAPS 1-D model
- 2017
-
Ingår i: Solar Energy. - : Elsevier. - 0038-092X .- 1471-1257. ; 157, s. 603-613
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Tidskriftsartikel (refereegranskat)abstract
- We present a (1-D) SCAPS device model to address the following: (i) the surface passivation mechanisms (i.e.field-effect and chemical), (ii) their impact on the CIGS solar cell performance for varying CIGS absorberthickness, (iii) the importance of fixed charge type (+/−) and densities of fixed and interface trap charges, and(iv) the reasons for discrete gains in the experimental cell efficiencies (previously reported) for varying CIGSabsorber thickness. First, to obtain a reliable device model, the proposed set of parameters is validated for bothfield-effect (due to fixed charges) and chemical passivation (due to interface traps) using a simple M-I-S teststructure and experimentally extracted values (previously reported) into the SCAPS simulator. Next, we providefigures of merits without any significant loss in the solar cell performances for minimum net −Qf and maximumacceptable limit for Dit, found to be ∼5 × 1012 cm−2 and ∼1 × 1013 cm−2 eV−1 respectively. We next showthat the influence of negative fixed charges in the rear passivation layer (i.e. field-effect passivation) is morepredominant than that of the positive fixed charges (i.e. counter-field effect) especially while considering ultrathin(<0.5 μm) absorber layers. Furthermore, we show the importance of rear reflectance on the short-circuitphotocurrent densities while scaling down the CIGS absorber layers below 0.5 μm under interface chemical andfield-effect passivation mechanisms. Finally, we provide the optimal rear passivation layer parameters for efficienciesgreater than 20% with ultra-thin CIGS absorber thickness (<0.5 μm). Based on these simulation results,we confirm that a negatively charged rear surface passivation with nano-point contact approach is efficient forthe enhancement of cell performances, especially while scaling down the absorber thickness below 0.5 μm.
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| 8. |
- Kotipalli, Ratan, et al.
(författare)
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Influence of Ga/(Ga plus In) grading on deep-defect states of Cu(In, Ga)Se-2 solar cells
- 2015
-
Ingår i: Physica Status Solidi. Rapid Research Letters. - : Wiley. - 1862-6254 .- 1862-6270. ; 9:3, s. 157-160
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Tidskriftsartikel (refereegranskat)abstract
- The benefits of gallium (Ga) grading on Cu(In, Ga) Se-2 (CIGS) solar cell performance are demonstrated by comparing with ungraded CIGS cells. Using drive-level capacitance profiling (DLCP) and admittance spectroscopy (AS) analyses, we show the influence of Ga grading on the spatial variation of deep defects, free-carrier densities in the CIGS absorber, and their impact on the cell's open-circuit voltage V-oc. The parameter most constraining the cell's Voc is found to be the deep-defect density close to the space charge region (SCR ). In ungraded devices, high deep-defect concentrations (4.2 x 1016 cm(-3)) were observed near the SCR, offering a source for Shockley Read-Hall recombination, reducing the cell's Voc. In graded devices, the deep-defect densities near the SCR decreased by one order of magnitude (2.5 x 1015 cm(-3)) for back surface graded devices, and almost two orders of magnitude (8.6 x 1014 cm(-3)) for double surface graded devices, enhancing the cell's Voc. In compositionally graded devices, the free-carrier density in the absorber's bulk decreased in tandem with the ratio of gallium to gallium plus indium ratio GGI = Ga/(Ga + In), increasing the activation energy, hindering the ionization of the defect states at room temperature and enhancing their role as recombination centers within the energy band.
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| 9. |
- Kotipalli, R., et al.
(författare)
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Investigating the electronic properties of Al2O3/Cu(In, Ga)Se-2 interface
- 2015
-
Ingår i: AIP Advances. - : AIP Publishing. - 2158-3226. ; 5:10
-
Tidskriftsartikel (refereegranskat)abstract
- Atomic layer deposited (ALD) Al2O3 films on Cu(In, Ga)Se-2 (CIGS) surfaces have been demonstrated to exhibit excellent surface passivation properties, which is advantageous in reducing recombination losses at the rear metal contact of CIGS thin-film solar cells. Here, we report, for the first time, experimentally extracted electronic parameters, i.e. fixed charge density (Q(f)) and interface-trap charge density (D-it), for as-deposited (AD) and post-deposition annealed (PDA) ALD Al2O3 films on CIGS surfaces using capacitance-voltage (C-V) and conductance-frequency (G-f) measurements. These results indicate that the AD films exhibit positive fixed charges Q(f) (approximately 10(12) cm(-2)), whereas the PDA films exhibit a very high density of negative fixed charges Q(f) (approximately 10(13) cm(-2)). The extracted D-it values, which reflect the extent of chemical passivation, were found to be in a similar range of order (approximately 10(12) cm(-2) eV(-1)) for both AD and PDA samples. The high density of negative Q(f) in the bulk of the PDA Al2O3 film exerts a strong Coulomb repulsive force on the underlying CIGS minority carriers (n(s)), preventing them to recombine at the CIGS/Al2O3 interface. Using experimentally extracted Q(f) and D-it values, SCAPS simulation results showed that the surface concentration of minority carriers (n(s)) in the PDA films was approximately eight-orders of magnitude lower than in the AD films. The electrical characterization and estimations presented in this letter construct a comprehensive picture of the interfacial physics involved at the Al2O3/CIGS interface. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
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| 10. |
- Ledinek, Dorothea, et al.
(författare)
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Thickness and Ga content variations in co-evaporated CIGS solar cells with a flat Ga profile : an electrical characteriyation
- 2014
-
Ingår i: EU PVSEC 2014 Proceedings Papers. - Munchen. ; , s. 1832-1836
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this work an extensive experimental series has been carried out by co-evaporating CIGS layers with varying thickness (0.5, 1.0, 1.5 µm) and varying Ga content (Ga/(Ga+In)=0.15, 0.30, 0.45 and 0.60). In all CIGS layers the Cu concentration has been held constant at Cu/(In+Ga)=0.85. The cells have been characterized with dark and light current voltage measurements, external quantum efficiency measurements and apparent quantum efficiency measurements at negative bias. In agreement with the literature, we observe a distinctively shorter collection length for high Ga concentrations and voltage dependent photo current collection for all cells. Voltage dependent current collection however cannot alone explain our data and the cells need to be described with an illumination dependent diode current or photo current. The generation dependent diode or photo current increase the slope of the light JV curve at negative bias voltage for all solar cells and dominates the slope in cells with 0.5 µm thin absorbers regardless of Ga content. We propose that this behavior is connected to the recombination at the back contact, as it is smaller in the cells with thick absorber layers and since we do not observe the same behavior in back side passivated cells. Keywords: Cu(InGa)Se2, Modelling, Electrical Characterization, Shunting, Ga content, thin absorbers, superposition principle, shifting approximation
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| 11. |
- Poncelet, Olivier, et al.
(författare)
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Optimisation of rear reflectance in ultra-thin CIGS solar cells towards>20% efficiency
- 2017
-
Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X .- 1471-1257. ; 146, s. 443-452
-
Tidskriftsartikel (refereegranskat)abstract
- In order to decrease their cost and the use of rare metal elements, thin film solar cell thicknesses are con-tinuously reduced at the expense of their efficiency, due to a lack of absorption for long wavelengths.Optimisation of cells rear reflectance (Rb) thus becomes meaningful to provide non-absorbed light a sec-ond chance to be harvested by the active cell layer. In this sense, we present a way to keep the rear reflec-tance in advanced Cu(In, Ga) Se2(CIGS) cell as high as possible while keeping in mind the progressalready done regarding the rear passivation techniques. We show that introducing a stack of thin Al2O3 and aluminium between the CIGS layer and the rear molybdenum electrode increases Rbup to92% in the long wavelength 800–1100 nm range. Several other stacks, using MgF2, SiO2or TiO2, are opti-mised in order to investigate the best trade-off between passivation, material consumption and perfor-mances, resulting in Rbranging from 42% (moderate case) to 99% in the best case. Those CIGS rearinterface reflectance optimisations were performed by using a standard transfer matrix method (TMM)in the long wavelength range. Seven interesting stacks are then analysed for solar cell performances usingSCAPS simulation software to understand the impact of rear reflectance on short circuit current density(Jsc) and eventually on the cell efficiency (g), for ultra-thin CIGS absorber thicknesses (<1 lm). Based onthese results, we propose Rboptimisation to achieve Jsc> 40 mA/cm2and g > 20% with a 500 nm-thickCIGS absorber film using CIGS-Al2O3-Mo stack, where the Al2O3thickness can be chosen in between104 and 139 nm. This way, we can ensure good rear reflectance (Rb= 65%) and reduced interface recom-bination while being industrially feasible with present technologies.
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| 12. |
- 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
-
Ingår i: Advanced Materials Interfaces. - : Wiley. - 2196-7350. ; 5:2
-
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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| 13. |
- Salome, Pedro M. P., et al.
(författare)
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The effect of high growth temperature on Cu(In,Ga)Se-2 thin film solar cells
- 2014
-
Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 123, s. 166-170
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Tidskriftsartikel (refereegranskat)abstract
- The morphological, elemental distribution and electrical performance effects of increasing the Cu(In,Ga) Se-2 (CIGS) growth substrate temperature are studied. While the increased substrate growth temperature with no other modifications led to increased CIGS grain size, it also resulted in depth profile flattening of the [Ga]/([Ga]+[In]) ratio. Tuning the Ga profile in the high temperature process led to a more desirable [Ga]/([Ga]+[In]) depth profile and allowed a comparison between high and standard temperature. Devices prepared at higher temperature showed an improved grain size and the electrical performance is very similar to that of the reference sample prepared at a standard temperature.
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| 14. |
- Tutundzic, Merve, et al.
(författare)
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Toward Efficient and Fully Scalable Sputtered NiOx-Based Inverted Perovskite Solar Modules via Co-Ordinated Modification Strategies
- 2023
-
Ingår i: Solar RRL. - : John Wiley & Sons. - 2367-198X.
-
Tidskriftsartikel (refereegranskat)abstract
- Sputtered nickel oxide (NiOx) has become one of the most promising inorganic hole transport layers for p–i–n perovskite solar cells (PSCs) due to its appealing features such as its robust nature, low material cost, and easy integration to tandem structures and large-area applications. However, the main drawback with NiOx-based PSCs is typically low open-circuit voltage (VOC) due to the inferior energy-level alignment, low charge mobility, and high recombination at the interface. Herein, two types of phosphonic acid self-assembled monolayers (SAMs) deposited by blade coating as an interfacial layer to modulate the sputtered NiOx/perovskite interface properties are used. While sputtered NiOx serves as a conformally coated hole selective layer, the ultrathin SAM interlayer facilitates the hole extraction and minimizes the energy loss at the interface. Co-ordinately introduced stabilizing additive, namely octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (I-76), further improves the device performance of NiOx/SAM-based PSCs, resulting in VOC of 1.14 V and a power conversion efficiency of 21.8%. By applying these strategies for perovskite module upscaling, aperture area module efficiencies of 19.7%, 17.5%, and 15.5% for perovskite minimodules of 4, 16, and 100 cm2 are demonstrated, corresponding to active area module efficiencies of 20.4%, 18.0%, and 16.4%, respectively.
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| 15. |
- Vermang, Bart, 1981-, et al.
(författare)
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Development of Rear Surface Passivated Cu(In,Ga)Se2 Thin Film Solar Cells with Nano-Sized Local Rear Point Contacts
- 2013
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 117:SI, s. 505-511
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Tidskriftsartikel (refereegranskat)abstract
- For the first time, a novel rear contacting structure for copper indium gallium (di)selenide (CIGS) thin film solar cells is discussed theoretically, developed in an industrially viable way, and demonstrated in tangible devices. The proposed cell design reduces back contacting area by combining a rear surface passivation layer and nano-sized local point contacts. Atomic layer deposition (ALD) of Al2O3 is used to passivate the CIGS surface and the formation of nano-sphere shaped precipitates in chemical bath deposition (CBD) of CdS to generate point contact openings. The Al2O3 rear surface passivated CIGS solar cells with nano-sized local rear point contacts show a significant improvement in open circuit voltage (VOC) compared to unpassivated reference cells. Comparing the passivated devices to solar cell capacitance simulator (SCAPS) modeling indicates that this increase is attributed to a decrease in rear surface recombination of a few orders.
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| 16. |
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| 17. |
- Vermang, Bart, et al.
(författare)
-
Highly reflective rear surface passivation design for ultra-thin Cu(In,Ga) Se-2 solar cells
- 2015
-
Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 582, s. 300-303
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Tidskriftsartikel (refereegranskat)abstract
- Al2O3 rear surface passivated ultra-thin Cu(In,Ga)Se-2 (CIGS) solar cells with Mo nano-particles (NPs) as local rear contacts are developed to demonstrate their potential to improve optical confinement in ultra-thin CIGS solar cells. The CIGS absorber layer is 380 nm thick and the Mo NPs are deposited uniformly by an up-scalable technique and have typical diameters of 150 to 200 nm. The Al2O3 layer passivates the CIGS rear surface between the Mo NPs, while the rear CIGS interface in contact with the Mo NP is passivated by [Ga]/([Ga] + [In]) (GGI) grading. It is shown that photon scattering due to the Mo NP contributes to an absolute increase in short circuit current density of 3.4 mA/cm(2); as compared to equivalent CIGS solar cells with a standard back contact.
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| 18. |
- Vermang, Bart, 1981-, et al.
(författare)
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Improved Rear Surface Passivation of Cu(In,Ga)Se2 Solar Cells : A Combination of an Al2O3 Rear Surface Passivation Layer and Nano-Sized Local Rear Point Contacts
- 2014
-
Ingår i: IEEE Journal of Photovoltaics. - 2156-3381 .- 2156-3403. ; 4:1, s. 486-492
-
Tidskriftsartikel (refereegranskat)abstract
- An innovative rear contacting structure for copper indium gallium (di) selenide (CIGS) thin-film solar cells is developed in an industrially viable way and demonstrated in tangible devices. The idea stems from the silicon (Si) industry, where rear surface passivation layers are combined with micron-sized local point contacts to boost the open-circuit voltage (VOC) and, hence, cell efficiency. However, compared with Si solar cells, CIGS solar cell minority carrier diffusion lengths are several orders lower in magnitude. Therefore, the proposed CIGS cell design reduces rear surface recombination by combining a rear surface passivation layer and nanosized local point contacts. Atomic layer deposition of Al2O3 is used to passivate the CIGS surface and the formation of nanosphere-shaped precipitates in chemical bath deposition of CdS to generate nanosized point contact openings. The manufactured Al2O3 rear surface passivated CIGS solar cells with nanosized local rear point contacts show a significant improvement in VOC compared with unpassivated reference cells.
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| 19. |
- 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
-
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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| 20. |
- Vermang, Bart, et al.
(författare)
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Potential-induced optimization of ultra-thin rear surface passivated CIGS solar cells
- 2014
-
Ingår i: Physica Status Solidi. Rapid Research Letters. - : Wiley. - 1862-6254 .- 1862-6270. ; 8:11, s. 908-911
-
Tidskriftsartikel (refereegranskat)abstract
- Ultra-thin Cu(In,Ga)Se-2 (CIGS) solar cells with an Al2O3 rear surface passivation layer between the rear contact and absorber layer frequently show a roll-over effect in the J-V curve, lowering the open circuit voltage (V-OC), short circuit current (J(SC)) and fill factor (FF), similar to what is observed for Na-deficient devices. Since Al2O3 is a well-known barrier for Na, this behaviour can indeed be interpreted as due to lack of Na in the CIGS absorber layer. In this work, applying an electric field between the backside of the soda lime glass (SLG) substrate and the SLG/rear-contact interface is investi-gated as potential treatment for such Na-deficient rear surface passivated CIGS solar cells. First, an electrical field of +50 V is applied at 85 degrees C, which increases the Na concentration in the CIGS absorber layer and the CdS buffer layer as measured by glow discharge optical emission spectroscopy (GDOES). Subsequently, the field polarity is reversed and part of the previously added Na is removed. This way, the J -V curve roll-over related to Na deficiency disappears and the V-OC (+25 mV), J(SC)(+2.3 mA/cm(2)) and FF (+13.5% absolute) of the rear surface passivated CIGS solar cells are optimized.
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| 21. |
- 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
-
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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| 22. |
- 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
-
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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| 23. |
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