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| 2. |
- Salomé, Pedro M. P., et al.
(author)
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Cu(In,Ga)Se-2 Solar Cells With Varying Na Content Prepared on Nominally Alkali-Free Glass Substrates
- 2013
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In: IEEE Journal of Photovoltaics. - 2156-3381. ; 3:2, s. 852-858
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Journal article (peer-reviewed)abstract
- In this paper, Cu(In,Ga)Se-2 (CIGS) thin-film solar cells are prepared on nominally alkali-free glass substrates using an in-line CIGS growth process. As compared with, for example, borosilicate glass or quartz, the glass is engineered to have similar thermal expansion coefficient as soda-lime glass (SLG) but with alkali content close to zero. Na is incorporated in the CIGS material using an ex-situ deposited NaF precursor layer evaporated onto the Mo back contact. Several thicknesses of the NaF layer were tested. The results show that there is a process window, between 15 and 22.5 nm NaF, where the solar cell conversion efficiency is comparable with or exceeding that of SLG references. The effect of an NaF layer that is too thin on the solar cell parameters was mainly lowering the open-circuit voltage, which points to a lower effective dopant concentration in the CIGS layer and is also consistent with presented C-V measurements and modeling results. For excessively thick NaF layers, delamination of the CIGS layer occurred. Additional measurements, such as scanning electron microscopy (SEM), secondary ion mass spectrometry, capacitance-voltage analysis (C-V), time-resolved photoluminescence (TRPL), external quantum efficiency (EQE), current-voltage analysis (J-V), and modeling, are presented, and the results are discussed.
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| 3. |
- Fjällström, Viktor, et al.
(author)
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Potential-Induced Degradation of CuIn1-xGaxSe2 Thin Film Solar Cells
- 2013
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In: IEEE Journal of Photovoltaics. - 2156-3381. ; 3:3, s. 1090-1094
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Journal article (peer-reviewed)abstract
- The use of Na-free or low Na content glass substrates is observed to enhance the resiliency to potential-induced degradation, as compared with glass substrates with high Na content, such as soda lime glass (SLG). The results from stress tests in this study suggest that degradation caused by a combination of heat and bias across the SLG substrate is linked to increased Na concentration in the CdS and Cu(In,Ga)Se-2 (CIGS) layers in CIGS-based solar cells. The degradation during the bias stress is dramatic. The efficiency drops to close to 0% after 50 h of stressing. On the other hand, cells on Na-free and low Na content substrates exhibited virtually no efficiency degradation. The degraded cells showed partial recovery by resting at room temperature without bias; thus, the degradation is nonpermanent and may be due to Na migration and accumulation rather than chemical reaction.
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| 4. |
- Hultqvist, Adam, et al.
(author)
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Performance of Cu(In,Ga)Se-2 solar cells using nominally alkali free glass substrates with varying coefficient of thermal expansion
- 2013
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 114:9, s. 094501-
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Journal article (peer-reviewed)abstract
- In this report, Cu(In,Ga)Se-2, CIGS, solar cell devices have been fabricated on nominally alkali free glasses with varying coefficients of thermal expansion (CTE) from 50 to 95* 10(-7)/degrees C. A layer of NaF deposited on top of the Mo was used to provide Na to the CIGS film. Increasing the glass CTE leads to a change of stress state of the solar cell stack as evidenced by measured changes of stress state of the Mo layer after CIGS deposition. The open circuit voltage, the short circuit current density, and the fill factors, for solar cells made on the various substrates, are all found to increase with CTE to a certain point. The median energy conversion efficiency values for 32 solar cells increases from 14.6% to the lowest CTE glass to 16.5% and 16.6%, respectively, for the two highest CTE glasses, which have CTE values closest to that of the soda lime glass. This is only slightly lower than the 17.0% median of soda lime glass reference devices. We propose a model where an increased defect density in the CIGS layer caused by thermal mismatch during cool-down is responsible for the lower efficiency for the low CTE glass substrates.
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| 5. |
- Salome, Pedro M. P., et al.
(author)
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Incorporation of Na in Cu(In,Ga)Se-2 Thin-Film Solar Cells : A Statistical Comparison Between Na From Soda-Lime Glass and From a Precursor Layer of NaF
- 2014
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In: IEEE Journal of Photovoltaics. - 2156-3381 .- 2156-3403. ; 4:6, s. 1659-1664
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Journal article (peer-reviewed)abstract
- The presence of Na in Cu(In,Ga)Se-2 layers increases the electrical performance of this type of thin- film solar cell. A detailed comparison of incorporating Na in the CIGS layer by two different methods is performed by evaluating several hundred devices fabricated under similar conditions. The firstmethod is based on the conventionally used Na diffusion from the soda-lime glass substrate, whereas the second method is based on a NaF precursor layer deposited on a Mo- coated alkali- free glass substrate. The sample where Na is introduced by using a NaF precursor layer shows an orientation weighted toward (2 0 4)/(2 2 0) and a net acceptor concentration of 3.4 x 10(16) cm(-3), while SLG shows a (1 1 2) orientation with a 2.9 x 10(16) cm(-3) acceptor concentration. Both sample types show close identical elemental depth profiles, morphology, and electrical performance.
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| 6. |
- Salome, Pedro M. P., et al.
(author)
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The effect of high growth temperature on Cu(In,Ga)Se-2 thin film solar cells
- 2014
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In: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 123, s. 166-170
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Journal article (peer-reviewed)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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| 7. |
- Gaziano, Liam, et al.
(author)
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Actionable druggable genome-wide Mendelian randomization identifies repurposing opportunities for COVID-19
- 2021
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In: Nature Medicine. - : Springer Nature. - 1078-8956 .- 1546-170X. ; 27:4
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Journal article (peer-reviewed)abstract
- Large-scale Mendelian randomization and colocalization analyses using gene expression and soluble protein data for 1,263 actionable druggable genes, which encode protein targets for approved drugs or drugs in clinical development, identify IFNAR2 and ACE2 as the most promising therapeutic targets for early management of COVID-19. Drug repurposing provides a rapid approach to meet the urgent need for therapeutics to address COVID-19. To identify therapeutic targets relevant to COVID-19, we conducted Mendelian randomization analyses, deriving genetic instruments based on transcriptomic and proteomic data for 1,263 actionable proteins that are targeted by approved drugs or in clinical phase of drug development. Using summary statistics from the Host Genetics Initiative and the Million Veteran Program, we studied 7,554 patients hospitalized with COVID-19 and >1 million controls. We found significant Mendelian randomization results for three proteins (ACE2, P = 1.6 x 10(-6); IFNAR2, P = 9.8 x 10(-11) and IL-10RB, P = 2.3 x 10(-14)) using cis-expression quantitative trait loci genetic instruments that also had strong evidence for colocalization with COVID-19 hospitalization. To disentangle the shared expression quantitative trait loci signal for IL10RB and IFNAR2, we conducted phenome-wide association scans and pathway enrichment analysis, which suggested that IFNAR2 is more likely to play a role in COVID-19 hospitalization. Our findings prioritize trials of drugs targeting IFNAR2 and ACE2 for early management of COVID-19.
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