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Jamarkattel MK, Mathew X, Phillips AB, Bastola E, Subedi KK, Alfadhili FK, Abudulimu A, Friedl JD, Awni RA, Li DB, Razooqi MA, Koirala P, Collins RW, Yan Y, Ellingson RJ, Heben MJ. Reduced Recombination and Improved Performance of CdSe/CdTe Solar Cells due to Cu Migration Induced by Light Soaking. ACS Appl Mater Interfaces 2022; 14:19644-19651. [PMID: 35451818 DOI: 10.1021/acsami.1c23937] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The performance of CdTe solar cells has advanced impressively in recent years with the incorporation of Se. Instabilities associated with light soaking and copper reorganization have been extensively examined for the previous generation of CdS/CdTe solar cells, but instabilities in Cu-doped Se-alloyed CdTe devices remain relatively unexplored. In this work, we fabricated a range of CdSe/CdTe solar cells by sputtering CdSe layers with thicknesses of 100, 120, 150, 180, and 200 nm on transparent oxide-coated glass and then depositing CdTe by close-spaced sublimation. After CdCl2 annealing, Cu-doping, and back metal deposition, a variety of analyses were performed both before and after light soaking to understand the changes in device performance. The device efficiency was degraded with light soaking in most cases, but devices fabricated with a CdSe layer thickness of 120 nm showed reasonably good efficiency initially (13.5%) and a dramatic improvement with light soaking (16.5%). The efficiency improvement is examined within the context of Cu ion reorganization that is well known for CdS/CdTe devices. Low-temperature photoluminescence data and Voc versus temperature measurements indicate a reduction in nonradiative recombination due to the passivation of defects and defect complexes in the graded CdSexTe1-x layer.
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Affiliation(s)
- Manoj K Jamarkattel
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
| | - Xavier Mathew
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
- Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Temixco, Morelos 62580, Mexico
| | - Adam B Phillips
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
| | - Ebin Bastola
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
| | - Kamala Khanal Subedi
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
| | - Fadhil K Alfadhili
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
| | - Abasi Abudulimu
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
| | - Jared D Friedl
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
| | - Rasha A Awni
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
| | - Deng-Bing Li
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
| | - Mohammed A Razooqi
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
| | - Prakash Koirala
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
| | - Robert W Collins
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
| | - Yanfa Yan
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
| | - Randy J Ellingson
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
| | - Michael J Heben
- Wright Center for Photovoltaic Innovation and Commercialization, Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606, United States
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Alaani MAR, Koirala P, Phillips AB, Liyanage GK, Awni RA, Sapkota DR, Ramanujam B, Heben MJ, O’Leary SK, Podraza NJ, Collins RW. Optical Properties of Magnesium-Zinc Oxide for Thin Film Photovoltaics. Materials (Basel) 2021; 14:ma14195649. [PMID: 34640041 PMCID: PMC8510442 DOI: 10.3390/ma14195649] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 09/20/2021] [Accepted: 09/23/2021] [Indexed: 12/28/2022]
Abstract
Motivated by their utility in CdTe-based thin film photovoltaics (PV) devices, an investigation of thin films of the magnesium-zinc oxide (MgxZn1−xO or MZO) alloy system was undertaken applying spectroscopic ellipsometry (SE). Dominant wurtzite phase MZO thin films with Mg contents in the range 0 ≤ x ≤ 0.42 were deposited on room temperature soda lime glass (SLG) substrates by magnetron co-sputtering of MgO and ZnO targets followed by annealing. The complex dielectric functions ε of these films were determined and parameterized over the photon energy range from 0.73 to 6.5 eV using an analytical model consisting of two critical point (CP) oscillators. The CP parameters in this model are expressed as polynomial functions of the best fitting lowest CP energy or bandgap E0 = Eg, which in turn is a quadratic function of x. As functions of x, both the lowest energy CP broadening and the Urbach parameter show minima for x ~ 0.3, which corresponds to a bandgap of 3.65 eV. As a result, it is concluded that for this composition and bandgap, the MZO exhibits either a minimum concentration of defects in the bulk of the crystallites or a maximum in the grain size, an observation consistent with measured X-ray diffraction line broadenings. The parametric expression for ε developed here is expected to be useful in future mapping and through-the-glass SE analyses of partial and complete PV device structures incorporating MZO.
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Affiliation(s)
- Mohammed A. Razooqi Alaani
- Wright Center for Photovoltaics Innovation & Commercialization, Department of Physics & Astronomy, University of Toledo, Toledo, OH 43606, USA; (P.K.); (A.B.P.); (G.K.L.); (R.A.A.); (D.R.S.); (B.R.); (M.J.H.)
- Correspondence: (M.A.R.A.); (N.J.P.); (R.W.C.)
| | - Prakash Koirala
- Wright Center for Photovoltaics Innovation & Commercialization, Department of Physics & Astronomy, University of Toledo, Toledo, OH 43606, USA; (P.K.); (A.B.P.); (G.K.L.); (R.A.A.); (D.R.S.); (B.R.); (M.J.H.)
| | - Adam B. Phillips
- Wright Center for Photovoltaics Innovation & Commercialization, Department of Physics & Astronomy, University of Toledo, Toledo, OH 43606, USA; (P.K.); (A.B.P.); (G.K.L.); (R.A.A.); (D.R.S.); (B.R.); (M.J.H.)
| | - Geethika K. Liyanage
- Wright Center for Photovoltaics Innovation & Commercialization, Department of Physics & Astronomy, University of Toledo, Toledo, OH 43606, USA; (P.K.); (A.B.P.); (G.K.L.); (R.A.A.); (D.R.S.); (B.R.); (M.J.H.)
| | - Rasha A. Awni
- Wright Center for Photovoltaics Innovation & Commercialization, Department of Physics & Astronomy, University of Toledo, Toledo, OH 43606, USA; (P.K.); (A.B.P.); (G.K.L.); (R.A.A.); (D.R.S.); (B.R.); (M.J.H.)
| | - Dhurba R. Sapkota
- Wright Center for Photovoltaics Innovation & Commercialization, Department of Physics & Astronomy, University of Toledo, Toledo, OH 43606, USA; (P.K.); (A.B.P.); (G.K.L.); (R.A.A.); (D.R.S.); (B.R.); (M.J.H.)
| | - Balaji Ramanujam
- Wright Center for Photovoltaics Innovation & Commercialization, Department of Physics & Astronomy, University of Toledo, Toledo, OH 43606, USA; (P.K.); (A.B.P.); (G.K.L.); (R.A.A.); (D.R.S.); (B.R.); (M.J.H.)
| | - Michael J. Heben
- Wright Center for Photovoltaics Innovation & Commercialization, Department of Physics & Astronomy, University of Toledo, Toledo, OH 43606, USA; (P.K.); (A.B.P.); (G.K.L.); (R.A.A.); (D.R.S.); (B.R.); (M.J.H.)
| | - Stephen K. O’Leary
- School of Engineering, The University of British Columbia Okanagan, 3333 University Way, Kelowna, BC V1V 1V7, Canada;
| | - Nikolas J. Podraza
- Wright Center for Photovoltaics Innovation & Commercialization, Department of Physics & Astronomy, University of Toledo, Toledo, OH 43606, USA; (P.K.); (A.B.P.); (G.K.L.); (R.A.A.); (D.R.S.); (B.R.); (M.J.H.)
- Correspondence: (M.A.R.A.); (N.J.P.); (R.W.C.)
| | - Robert W. Collins
- Wright Center for Photovoltaics Innovation & Commercialization, Department of Physics & Astronomy, University of Toledo, Toledo, OH 43606, USA; (P.K.); (A.B.P.); (G.K.L.); (R.A.A.); (D.R.S.); (B.R.); (M.J.H.)
- Correspondence: (M.A.R.A.); (N.J.P.); (R.W.C.)
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Bista SS, Li DB, Awni RA, Song Z, Subedi KK, Shrestha N, Rijal S, Neupane S, Grice CR, Phillips AB, Ellingson RJ, Heben M, Li JV, Yan Y. Effects of Cu Precursor on the Performance of Efficient CdTe Solar Cells. ACS Appl Mater Interfaces 2021; 13:38432-38440. [PMID: 34347421 DOI: 10.1021/acsami.1c11784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Copper (Cu) incorporation is a key process for fabricating efficient CdTe-based thin-film solar cells and has been used in CdTe-based solar cell module manufacturing. Here, we investigate the effects of different Cu precursors on the performance of CdTe-based thin-film solar cells by incorporating Cu using a metallic Cu source (evaporated Cu) and ionic Cu sources (solution-processed cuprous chloride (CuCl) and copper chloride (CuCl2)). We find that ionic Cu precursors offer much better control in Cu diffusion than the metallic Cu precursor, producing better front junction quality, lower back-barrier heights, and better bulk defect property. Finally, outperforming power conversion efficiencies of 17.2 and 17.5% are obtained for devices with cadmium sulfide and zinc magnesium oxide as the front window layers, respectively, which are among the highest reported CdTe solar cells efficiencies. Our results suggest that an ionic Cu precursor is preferred as the dopant to fabricate efficient CdTe thin-film solar cells and modules.
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Affiliation(s)
- Sandip S Bista
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, Ohio 43606, United States
| | - Deng-Bing Li
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, Ohio 43606, United States
| | - Rasha A Awni
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, Ohio 43606, United States
| | - Zhaoning Song
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, Ohio 43606, United States
| | - Kamala K Subedi
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, Ohio 43606, United States
| | - Niraj Shrestha
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, Ohio 43606, United States
| | - Suman Rijal
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, Ohio 43606, United States
| | - Sabin Neupane
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, Ohio 43606, United States
| | - Corey R Grice
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, Ohio 43606, United States
| | - Adam B Phillips
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, Ohio 43606, United States
| | - Randy J Ellingson
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, Ohio 43606, United States
| | - Michael Heben
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, Ohio 43606, United States
| | - Jian V Li
- Department of Aeronautics and Astronautics, National Cheng Kung University, 70101 Tainan, Taiwan
| | - Yanfa Yan
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, Ohio 43606, United States
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Alfadhili FK, Phillips AB, Subedi KK, Perkins CL, Halaoui AI, Jamarkattel MK, Anwar BM, Liyanage GK, Li DB, Grice CR, Yan Y, Ellingson RJ, Heben MJ. Back-Surface Passivation of CdTe Solar Cells Using Solution-Processed Oxidized Aluminum. ACS Appl Mater Interfaces 2020; 12:51337-51343. [PMID: 33146989 DOI: 10.1021/acsami.0c12800] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Although back-surface passivation plays an important role in high-efficiency photovoltaics, it has not yet been definitively demonstrated for CdTe. Here, we present a solution-based process, which achieves passivation and improved electrical performance when very small amounts of oxidized Al3+ species are deposited at the back surface of CdTe devices. The open circuit voltage (Voc) is increased and the fill factor (FF) and photoconversion efficiency (PCE) are optimized when the total amount added corresponds to ∼1 monolayer, suggesting that the passivation is surface specific. Addition of further Al3+ species, present in a sparse alumina-like layer, causes the FF and PCE to drop as the interface layer becomes blocking to current flow. The optimized deposit increases the average baseline PCE for both Cu-free devices and devices where Cu is present as a dopant. The greatest improvement is found when the Al3+ species are deposited prior to the CdCl2 activation step and Cu is employed. In this case, the best-cell efficiency was improved from 12.6 to 14.4%. Time-resolved photoluminescence measurements at the back surface and quantum efficiency measurements performed at the maximum power point indicate that the performance enhancement is due to a reduction in the interface recombination current at the back surface.
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Affiliation(s)
- Fadhil K Alfadhili
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, United States
| | - Adam B Phillips
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, United States
| | - Kamala Khanal Subedi
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, United States
| | - Craig L Perkins
- National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Adam I Halaoui
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, United States
| | - Manoj K Jamarkattel
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, United States
| | - Bhuiyan M Anwar
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, United States
| | - Geethika K Liyanage
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, United States
| | - Deng-Bing Li
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, United States
| | - Corey R Grice
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, United States
| | - Yanfa Yan
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, United States
| | - Randy J Ellingson
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, United States
| | - Michael J Heben
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, United States
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Li DB, Song Z, Bista SS, Alfadhili FK, Awni RA, Shrestha N, Rhiannon D, Phillips AB, Heben MJ, Ellingson RJ, Yan F, Yan Y. CuSCN as the Back Contact for Efficient ZMO/CdTe Solar Cells. Materials (Basel) 2020; 13:ma13081991. [PMID: 32344645 PMCID: PMC7215694 DOI: 10.3390/ma13081991] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 04/20/2020] [Accepted: 04/21/2020] [Indexed: 11/22/2022]
Abstract
The replacement of traditional CdS with zinc magnesium oxide (ZMO) has been demonstrated as being helpful to boost power conversion efficiency of cadmium telluride (CdTe) solar cells to over 18%, due to the reduced interface recombination and parasitic light absorption by the buffer layer. However, due to the atmosphere sensitivity of ZMO film, the post treatments of ZMO/CdTe stacks, including CdCl2 treatment, back contact deposition, etc., which are critical for high-performance CdTe solar cells became crucial challenges. To realize the full potential of the ZMO buffer layer, plenty of investigations need to be accomplished. Here, copper thiocyanate (CuSCN) is demonstrated to be a suitable back-contact material with multi-advantages for ZMO/CdTe solar cells. Particularly, ammonium hydroxide as the solvent for CuSCN deposition shows no detrimental impact on the ZMO layer during the post heat treatment. The post annealing temperature as well as the thickness of CuSCN films are investigated. Finally, a champion power conversion efficiency of 16.7% is achieved with an open-circuit voltage of 0.857 V, a short-circuit current density of 26.2 mA/cm2, and a fill factor of 74.0%.
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Affiliation(s)
- Deng-Bing Li
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, OH 43606, USA; (D.-B.L.); (Z.S.); (S.S.B.); (F.K.A.); (R.A.A.); (N.S.); (A.B.P.); (M.J.H.); (R.J.E.)
| | - Zhaoning Song
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, OH 43606, USA; (D.-B.L.); (Z.S.); (S.S.B.); (F.K.A.); (R.A.A.); (N.S.); (A.B.P.); (M.J.H.); (R.J.E.)
| | - Sandip S. Bista
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, OH 43606, USA; (D.-B.L.); (Z.S.); (S.S.B.); (F.K.A.); (R.A.A.); (N.S.); (A.B.P.); (M.J.H.); (R.J.E.)
| | - Fadhil K. Alfadhili
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, OH 43606, USA; (D.-B.L.); (Z.S.); (S.S.B.); (F.K.A.); (R.A.A.); (N.S.); (A.B.P.); (M.J.H.); (R.J.E.)
| | - Rasha A. Awni
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, OH 43606, USA; (D.-B.L.); (Z.S.); (S.S.B.); (F.K.A.); (R.A.A.); (N.S.); (A.B.P.); (M.J.H.); (R.J.E.)
| | - Niraj Shrestha
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, OH 43606, USA; (D.-B.L.); (Z.S.); (S.S.B.); (F.K.A.); (R.A.A.); (N.S.); (A.B.P.); (M.J.H.); (R.J.E.)
| | - DeMilt Rhiannon
- Ottawa Hills Junior/senior high school, Ottawa Hills Local Schools, Ottawa Hills, OH 43606, USA;
| | - Adam B. Phillips
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, OH 43606, USA; (D.-B.L.); (Z.S.); (S.S.B.); (F.K.A.); (R.A.A.); (N.S.); (A.B.P.); (M.J.H.); (R.J.E.)
| | - Michael J. Heben
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, OH 43606, USA; (D.-B.L.); (Z.S.); (S.S.B.); (F.K.A.); (R.A.A.); (N.S.); (A.B.P.); (M.J.H.); (R.J.E.)
| | - Randy J. Ellingson
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, OH 43606, USA; (D.-B.L.); (Z.S.); (S.S.B.); (F.K.A.); (R.A.A.); (N.S.); (A.B.P.); (M.J.H.); (R.J.E.)
| | - Feng Yan
- Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487, USA;
| | - Yanfa Yan
- Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo, OH 43606, USA; (D.-B.L.); (Z.S.); (S.S.B.); (F.K.A.); (R.A.A.); (N.S.); (A.B.P.); (M.J.H.); (R.J.E.)
- Correspondence:
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Alfadhili FK, Phillips AB, Liyanage GK, Gibbs JM, Jamarkattel MK, Heben MJ. Controlling Band Alignment at the Back Interface of Cadmium Telluride Solar Cells using ZnTe and Te Buffer Layers. ACTA ACUST UNITED AC 2019. [DOI: 10.1557/adv.2019.31] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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7
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Song Z, Shrestha N, Watthage SC, Liyanage GK, Almutawah ZS, Ahangharnejhad RH, Phillips AB, Ellingson RJ, Heben MJ. Impact of Moisture on Photoexcited Charge Carrier Dynamics in Methylammonium Lead Halide Perovskites. J Phys Chem Lett 2018; 9:6312-6320. [PMID: 30336064 DOI: 10.1021/acs.jpclett.8b02595] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Organic-inorganic metal halide perovskites are notoriously unstable in humid environments. While many studies have revealed the morphology and crystal structure changes that accompany exposure to humidity, little is known about changes to the photophysics that accompany the degradation process. By combining in situ steady-state and time-resolved photoluminescence with Hall effect measurements, we examined the changes in the photoexcited carrier dynamics for methylammonium lead iodide (MAPbI3) and bromide (MAPbBr3) films exposed to nitrogen gas containing water vapor at 80% relative humidity. The changes in the photophysics of MAPbI3 interacting with water follow a four-stage process, consisting of surface passivation, free electron doping, interfacial hydration, and bulk hydration. In contrast, MAPbBr3 exhibits only features associated with the first two stages, which occur at a faster rate. Our results elucidate the degradation mechanisms of perovskite films in high humidity from the perspective of the photophysics, providing insights for how humidity affects the stability of the perovskite materials.
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Affiliation(s)
- Zhaoning Song
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy , University of Toledo , 2801 West Bancroft Street , Toledo , Ohio 43606 United States
| | - Niraj Shrestha
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy , University of Toledo , 2801 West Bancroft Street , Toledo , Ohio 43606 United States
| | - Suneth C Watthage
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy , University of Toledo , 2801 West Bancroft Street , Toledo , Ohio 43606 United States
| | - Geethika K Liyanage
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy , University of Toledo , 2801 West Bancroft Street , Toledo , Ohio 43606 United States
| | - Zahrah S Almutawah
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy , University of Toledo , 2801 West Bancroft Street , Toledo , Ohio 43606 United States
| | - Ramez H Ahangharnejhad
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy , University of Toledo , 2801 West Bancroft Street , Toledo , Ohio 43606 United States
| | - Adam B Phillips
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy , University of Toledo , 2801 West Bancroft Street , Toledo , Ohio 43606 United States
| | - Randy J Ellingson
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy , University of Toledo , 2801 West Bancroft Street , Toledo , Ohio 43606 United States
| | - Michael J Heben
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy , University of Toledo , 2801 West Bancroft Street , Toledo , Ohio 43606 United States
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Shrestha N, Sapkota DR, Subedi KK, Pradhan P, Koirala P, Phillips AB, Collins RW, Heben MJ, Ellingson RJ. Identification of Defect Levels in Copper Indium Diselenide (CuInSe2) Thin Films via Photoluminescence Studies. ACTA ACUST UNITED AC 2018. [DOI: 10.1557/adv.2018.556] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Liyanage GK, Phillips AB, Alfadhili FK, Heben MJ. Numerical Modelling of Front Contact Alignment for High Efficiency Cd1-xZnxTe and Cd1-xMgxTe Solar Cells for Tandem Devices. ACTA ACUST UNITED AC 2018. [DOI: 10.1557/adv.2018.501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Shrestha N, Grice CR, Bastola E, Liyanage GK, Phillips AB, Heben MJ, Yan Y, Ellingson RJ. Low Temperature Photoluminescence Spectroscopy of Defect and Interband Transitions in CdSexTe1-x Thin Films. ACTA ACUST UNITED AC 2018. [DOI: 10.1557/adv.2018.516] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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11
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Almutawah ZS, Watthage SC, Song Z, Ahangharnejhad RH, Subedi KK, Shrestha N, Phillips AB, Yan Y, Ellingson RJ, Heben MJ. Enhanced Grain Size and Crystallinity in CH3NH3PbI3 Perovskite Films by Metal Additives to the Single-Step Solution Fabrication Process. ACTA ACUST UNITED AC 2018. [DOI: 10.1557/adv.2018.413] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Celik I, Mason BE, Phillips AB, Heben MJ, Apul D. Environmental Impacts from Photovoltaic Solar Cells Made with Single Walled Carbon Nanotubes. Environ Sci Technol 2017; 51:4722-4732. [PMID: 28234471 DOI: 10.1021/acs.est.6b06272] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
An ex-ante life cycle inventory was developed for single walled carbon nanotube (SWCNT) PV cells, including a laboratory-made 1% efficient device and an aspirational 28% efficient four-cell tandem device. The environmental impact of unit energy generation from the mono-Si PV technology was used as a reference point. Compared to monocrystalline Si (mono-Si), the environmental impacts from 1% SWCNT was ∼18 times higher due mainly to the short lifetime of three years. However, even with the same short lifetime, the 28% cell had lower environmental impacts than mono-Si. The effects of lifetime and efficiency on the environmental impacts were further examined. This analysis showed that if the SWCNT device efficiency had the same value as the best efficiency of the material under comparison, to match the total normalized impacts of the mono- and poly-Si, CIGS, CdTe, and a-Si devices, the SWCNT devices would need a lifetime of 2.8, 3.5, 5.3, 5.1, and 10.8 years, respectively. It was also found that if the SWCNT PV has an efficiency of 4.5% or higher, its energy payback time would be lower than other existing and emerging PV technologies. The major impacts of SWCNT PV came from the cell's materials synthesis.
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Affiliation(s)
- Ilke Celik
- School of Solar and Advanced Renewable Energy, Department of Civil Engineering, University of Toledo 2801 W. Bancroft St., Toledo, Ohio 43606, United States
| | - Brooke E Mason
- School of Solar and Advanced Renewable Energy, Department of Civil Engineering, University of Toledo 2801 W. Bancroft St., Toledo, Ohio 43606, United States
| | - Adam B Phillips
- School of Solar and Advanced Renewable Energy, Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo 2801 W. Bancroft St., Toledo, Ohio 43606, United States
| | - Michael J Heben
- School of Solar and Advanced Renewable Energy, Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo 2801 W. Bancroft St., Toledo, Ohio 43606, United States
| | - Defne Apul
- School of Solar and Advanced Renewable Energy, Department of Civil Engineering, University of Toledo 2801 W. Bancroft St., Toledo, Ohio 43606, United States
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Watthage SC, Song Z, Shrestha N, Phillips AB, Liyanage GK, Roland PJ, Ellingson RJ, Heben MJ. Enhanced Grain Size, Photoluminescence, and Photoconversion Efficiency with Cadmium Addition during the Two-Step Growth of CH 3NH 3PbI 3. ACS Appl Mater Interfaces 2017; 9:2334-2341. [PMID: 28009167 DOI: 10.1021/acsami.6b12627] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Control over grain size and crystallinity is important for preparation of methylammonium lead iodide (MAPbI3) solar cells. We explore the effects of using small concentrations of Cd2+ and unusually high concentrations of methylammonium iodide during the growth of MAPbI3 in the two-step solution process. In addition to improved crystallinity and an enhancement in the size of the grains, time-resolved photoluminescence measurements indicated a dramatic increase in the carrier lifetime. As a result, devices constructed with the Cd-modified perovskites showed nearly a factor of 2 improvement in the power conversion efficiency (PCE) relative to similar devices prepared without Cd addition. The grains also showed a higher degree of orientation in the ⟨110⟩ direction, indicating a change in the growth mechanism, and the films were compact and smooth. We propose a Cd-modified film growth mechanism that invokes a critical role for low-dimensional Cd perovskites to explain the experimental observations.
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Affiliation(s)
- Suneth C Watthage
- Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States
| | - Zhaoning Song
- Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States
| | - Niraj Shrestha
- Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States
| | - Adam B Phillips
- Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States
| | - Geethika K Liyanage
- Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States
| | - Paul J Roland
- Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States
| | - Randy J Ellingson
- Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States
| | - Michael J Heben
- Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States
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14
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Song Z, Werner J, Shrestha N, Sahli F, De Wolf S, Niesen B, Watthage SC, Phillips AB, Ballif C, Ellingson RJ, Heben MJ. Probing Photocurrent Nonuniformities in the Subcells of Monolithic Perovskite/Silicon Tandem Solar Cells. J Phys Chem Lett 2016; 7:5114-5120. [PMID: 27973901 DOI: 10.1021/acs.jpclett.6b02415] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Perovskite/silicon tandem solar cells with high power conversion efficiencies have the potential to become a commercially viable photovoltaic option in the near future. However, device design and optimization is challenging because conventional characterization methods do not give clear feedback on the localized chemical and physical factors that limit performance within individual subcells, especially when stability and degradation is a concern. In this study, we use light beam induced current (LBIC) to probe photocurrent collection nonuniformities in the individual subcells of perovskite/silicon tandems. The choices of lasers and light biasing conditions allow efficiency-limiting effects relating to processing defects, optical interference within the individual cells, and the evolution of water-induced device degradation to be spatially resolved. The results reveal several types of microscopic defects and demonstrate that eliminating these and managing the optical properties within the multilayer structures will be important for future optimization of perovskite/silicon tandem solar cells.
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Affiliation(s)
- Zhaoning Song
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo , 2801 West Bancroft Street, Toledo, Ohio 43606 United States
| | - Jérémie Werner
- Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), Ecole Polytechnique Fédérale de Lausanne (EPFL) , Rue de la Maladière 71b, 2002 Neuchâtel, Switzerland
| | - Niraj Shrestha
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo , 2801 West Bancroft Street, Toledo, Ohio 43606 United States
| | - Florent Sahli
- Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), Ecole Polytechnique Fédérale de Lausanne (EPFL) , Rue de la Maladière 71b, 2002 Neuchâtel, Switzerland
| | - Stefaan De Wolf
- Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), Ecole Polytechnique Fédérale de Lausanne (EPFL) , Rue de la Maladière 71b, 2002 Neuchâtel, Switzerland
| | - Björn Niesen
- Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), Ecole Polytechnique Fédérale de Lausanne (EPFL) , Rue de la Maladière 71b, 2002 Neuchâtel, Switzerland
- CSEM, PV-Center , Jaquet-Droz 1, 2002 Neuchâtel, Switzerland
| | - Suneth C Watthage
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo , 2801 West Bancroft Street, Toledo, Ohio 43606 United States
| | - Adam B Phillips
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo , 2801 West Bancroft Street, Toledo, Ohio 43606 United States
| | - Christophe Ballif
- Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), Ecole Polytechnique Fédérale de Lausanne (EPFL) , Rue de la Maladière 71b, 2002 Neuchâtel, Switzerland
- CSEM, PV-Center , Jaquet-Droz 1, 2002 Neuchâtel, Switzerland
| | - Randy J Ellingson
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo , 2801 West Bancroft Street, Toledo, Ohio 43606 United States
| | - Michael J Heben
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo , 2801 West Bancroft Street, Toledo, Ohio 43606 United States
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Phillips AB, Song Z, DeWitt JL, Stone JM, Krantz PW, Royston JM, Zeller RM, Mapes MR, Roland PJ, Dorogi MD, Zafar S, Faykosh GT, Ellingson RJ, Heben MJ. High speed, intermediate resolution, large area laser beam induced current imaging and laser scribing system for photovoltaic devices and modules. Rev Sci Instrum 2016; 87:093708. [PMID: 27782537 DOI: 10.1063/1.4962940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We have developed a laser beam induced current imaging tool for photovoltaic devices and modules that utilizes diode pumped Q-switched lasers. Power densities on the order of one sun (100 mW/cm2) can be produced in a ∼40 μm spot size by operating the lasers at low diode current and high repetition rate. Using galvanostatically controlled mirrors in an overhead configuration and high speed data acquisition, large areas can be scanned in short times. As the beam is rastered, focus is maintained on a flat plane with an electronically controlled lens that is positioned in a coordinated fashion with the movements of the mirrors. The system can also be used in a scribing mode by increasing the diode current and decreasing the repetition rate. In either mode, the instrument can accommodate samples ranging in size from laboratory scale (few cm2) to full modules (1 m2). Customized LabVIEW programs were developed to control the components and acquire, display, and manipulate the data in imaging mode.
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Affiliation(s)
- Adam B Phillips
- Wright Center for Photovoltaic Innovation and Commercialization (PVIC), Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, USA
| | - Zhaoning Song
- Wright Center for Photovoltaic Innovation and Commercialization (PVIC), Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, USA
| | - Jonathan L DeWitt
- Wright Center for Photovoltaic Innovation and Commercialization (PVIC), Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, USA
| | - Jon M Stone
- Wright Center for Photovoltaic Innovation and Commercialization (PVIC), Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, USA
| | - Patrick W Krantz
- Wright Center for Photovoltaic Innovation and Commercialization (PVIC), Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, USA
| | - John M Royston
- Wright Center for Photovoltaic Innovation and Commercialization (PVIC), Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, USA
| | - Ryan M Zeller
- Wright Center for Photovoltaic Innovation and Commercialization (PVIC), Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, USA
| | - Meghan R Mapes
- Wright Center for Photovoltaic Innovation and Commercialization (PVIC), Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, USA
| | - Paul J Roland
- Wright Center for Photovoltaic Innovation and Commercialization (PVIC), Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, USA
| | - Mark D Dorogi
- Willard and Kelsey Solar Group, Perrysburg, Ohio 43551, USA
| | - Syed Zafar
- Willard and Kelsey Solar Group, Perrysburg, Ohio 43551, USA
| | - Gary T Faykosh
- Willard and Kelsey Solar Group, Perrysburg, Ohio 43551, USA
| | - Randy J Ellingson
- Wright Center for Photovoltaic Innovation and Commercialization (PVIC), Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, USA
| | - Michael J Heben
- Wright Center for Photovoltaic Innovation and Commercialization (PVIC), Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606, USA
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16
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Phillips AB, Khanal RR, Song Z, Zartman RM, DeWitt JL, Stone JM, Roland PJ, Plotnikov VV, Carter CW, Stayancho JM, Ellingson RJ, Compaan AD, Heben MJ. Wiring-up carbon single wall nanotubes to polycrystalline inorganic semiconductor thin films: low-barrier, copper-free back contact to CdTe solar cells. Nano Lett 2013; 13:5224-5232. [PMID: 24156376 DOI: 10.1021/nl402659c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We have discovered that films of carbon single wall nanotubes (SWNTs) make excellent back contacts to CdTe devices without any modification to the CdTe surface. Efficiencies of SWNT-contacted devices are slightly higher than otherwise identical devices formed with standard Au/Cu back contacts. The SWNT layer is thermally stable and easily applied with a spray process, and SWNT-contacted devices show no signs of degradation during accelerated life testing.
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Affiliation(s)
- Adam B Phillips
- Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, School of Solar and Advanced Renewable Energy, University of Toledo , Toledo, Ohio 43606, United States
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17
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Hayes D, Mansour HM, Kirkby S, Phillips AB. Rapid acute onset of bronchiolitis obliterans syndrome in a lung transplant recipient after respiratory syncytial virus infection. Transpl Infect Dis 2012; 14:548-50. [PMID: 22650803 PMCID: PMC7169679 DOI: 10.1111/j.1399-3062.2012.00748.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 11/28/2011] [Accepted: 01/21/2012] [Indexed: 11/29/2022]
Abstract
Bronchiolitis obliterans syndrome (BOS) can have either an acute or chronic onset with an abrupt or insidious course. The diagnosis is typically achieved by physiological criteria with development of a sustained decline in expiratory flow rates for at least 3 weeks. We review the rapid development of acute BOS and bronchiectasis after respiratory syncytial virus infection in a lung transplant recipient, who had been doing well with normal pulmonary function for 3 years after lung transplantation.
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Affiliation(s)
- D Hayes
- The Ohio State University, Columbus, Ohio 43205, USA.
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Gomez D, Preston TJ, Olshove VF, Phillips AB, Galantowicz ME. Evaluation of air handling in a new generation neonatal oxygenator with integral arterial filter. Perfusion 2009; 24:107-12. [DOI: 10.1177/0267659109106825] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Prime volume of the cardiopulmonary bypass circuit may lead to significant hemodilution and the potential need for blood products for all patients, but may be more critical in the pediatric and, specifically, the neonatal patient. We report on the first use of the Terumo® CAPIOX® FX05 (Baby-FX™) oxygenator with integral arterial filter, prime volume 43 ml, evaluating performance and air-handling of six Baby-FX™ versus thirteen Baby-RX™ oxygenators. The Terumo Baby-FX™ primes and performs as easily as the Baby-RX™ series. A significant prime component in the neonatal CPB circuit can be the arterial line filter (ALF). Removal of the ALF may lead to significant reduction in prime volume, decreased exposure to foreign surfaces with subsequent reduction in inflammation, and potential elimination or reduction in blood product exposures.
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Affiliation(s)
- D Gomez
- Department of Cardiovascular Perfusion, The Heart Center, Nationwide Children’s Hospital, Columbus, Ohio, USA
| | - TJ Preston
- Department of Cardiovascular Perfusion, The Heart Center, Nationwide Children’s Hospital, Columbus, Ohio, USA
| | - VF Olshove
- Department of Cardiovascular Perfusion, The Heart Center, Nationwide Children’s Hospital, Columbus, Ohio, USA
| | - AB Phillips
- Department of Cardiothoracic Surgery, The Heart Center, Nationwide Children’s Hospital, Columbus, Ohio, USA; Department of Surgery, The Ohio State University, Columbus, Ohio, USA
| | - ME Galantowicz
- Department of Cardiothoracic Surgery, The Heart Center, Nationwide Children’s Hospital, Columbus, Ohio, USA; Department of Surgery, The Ohio State University, Columbus, Ohio, USA
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Abstract
We have recently shown that organo-metallic complexes formed by laser ablating transition metals in ethylene are high hydrogen absorbers at room temperature (Phillips and Shivaram 2008 Phys. Rev. Lett. 100 105505). Here we show that the absorption percentage depends strongly on the ethylene pressure. High ethylene pressures (>100 mTorr) result in a lowered hydrogen uptake. Transmission electron microscopy measurements reveal that while low pressure ablations result in metal atoms dispersed uniformly on a near atomic scale, high pressure ones yield distinct nanoparticles with electron energy-loss spectroscopy demonstrating that the metal atoms are confined solely to the nanoparticles.
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Affiliation(s)
- A B Phillips
- Department of Physics, University of Virginia, Charlottesville, VA 22901, USA
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20
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Phillips AB, Shivaram BS. High capacity hydrogen absorption in transition metal-ethylene complexes observed via nanogravimetry. Phys Rev Lett 2008; 100:105505. [PMID: 18352205 DOI: 10.1103/physrevlett.100.105505] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Indexed: 05/26/2023]
Abstract
Using a surface acoustic wave based high resolution gravimetric technique where samples close to a monolayer are measured we observe high weight percentage hydrogen (H(2)) uptake with rapid kinetics at room temperature in transition metal (TM) ethylene (C(2)H(4)) complexes formed by laser ablation. By ablating titanium (Ti) in C(2)H(4) we obtain a complex that exhibits 12 wt % uptake of H(2) with substitution by deuterium providing a doubling. Mass spectroscopic studies during ablation of Ti show presence of a species, with a mass = 78 amu, a likely candidate for the high H(2) uptake.
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Affiliation(s)
- A B Phillips
- Department of Physics, University of Virginia, Charlottesville, Virginia 22901, USA
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Abstract
We describe an apparatus assembled to measure hydrogen absorption on a monolayer of isolated nanometer scale entities. Utilizing inexpensive and readily available high frequency surface acoustic wave (SAW) sensors we achieve a sensitivity of 4 pg, sufficient to detect hydrogen uptake at less than 1% in nanogram level samples of such entities at room temperature. Results of hydriding rare earth metal nanoparticles and a transition metal-carbon complex measured with 315 MHz SAW resonators are presented. However, the design of our apparatus is general and can be used with a wide variety of commercial SAW sensors.
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Affiliation(s)
- A B Phillips
- Department of Physics, University of Virginia, Charlottesville, Virginia 22901, USA
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Abstract
BACKGROUND AND OBJECTIVE Laser tissue-welding has been used for anastomosis of carotid arteries. During welding, thermal injury sustained by the vessel walls should be minimized to prevent thrombosis. Two different types of lasers were used and effects on tissue damage were studied in vitro and in vivo. STUDY DESIGN/MATERIALS AND METHODS End-to-end anastomosis of dog carotid arteries (n = 10) was performed by using a human albumin solder (HAS) in conjunction with Nd:YAG or diode lasers (lambda = 1.32 microm and 1.9 microm, respectively). The arteries were evaluated for patency and evidence of histologic injury after 21 days. Another group of arteries was laser soldered in vitro to measure the intimal and adventitial temperatures by using thermocouples. RESULTS The arteries repaired with the diode laser sustained significantly less thermal damage than those repaired with Nd:YAG laser, both in vitro and in vivo. In particular, the intimal temperature was significantly lower (P < 0.05) for the diode than for the Nd:YAG repairs (approximately 35 degrees C and approximately 50 degrees C, respectively). In the latter group, the patency rate was 75%, but thrombosis occurred in 75% of the specimens at 21 days. All diode anastomoses were patent and thrombosis developed in only 17% of the arteries. CONCLUSION Use of the diode laser and albumin solders may provide a means to successfully repair carotid arteries with minimal thermal damage.
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Affiliation(s)
- A Lauto
- Center for Pediatric Urology and Minimal Invasive Urologic Surgery, New York Presbyterian Hospital-Weill Medical College of Cornell University, New York 10021, USA.
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Abstract
BACKGROUND AND OBJECTIVES To improve minimally invasive direct coronary artery bypass surgery (MID-CAB), new techniques of vascular anastomosis that are faster and more reliable need to be developed. STUDY DESIGN/MATERIALS AND METHODS Common carotids in a canine model were transected and an end-to-end anastomosis was performed by using one of four techniques (1) continuous 6-0 polypropylene closure (suture; n=6), (2) vascular clip (VCS; n=6), laser welding using 50% albumin solder with (3) a 1.32-micro laser (1.32las; n=6), and (4) a 1.9-micro diode laser (1.9las; n=4). Times for anastomosis (TA) were compared between groups by t-test. Pressures at which anastomosis failed (leak point pressure, LPP) were determined and compared by analysis of variance. RESULTS TA was faster for 1.32las and 1.9las at 8.4+/-0.7 and 7.8+/-0.3 min, respectively, when compared with suture at 13.8+/-1.0 min (P=0.001, confidence interval [CI]-8.1, -2.6 for 1.32las and CI -8.9, -3.1 for 1.9las). There was no statistical difference between VCS (8.3+/-3.3 min) and any other group (P > 0.17). LPPs (mm Hg) were similar for all groups: 350+/-37 for 1.32las, 280+/-31 for 1.9las, 347+/-46 for suture, and 358+/-53 for VCS, P=0.68. CONCLUSIONS In this study, laser welding using 50% human albumin solder resulted in faster anastomotic times. Anastomoses were equivalent to conventional sutured anastomoses in failing at similar pressures. Laser welding using human albumin solder may be advantageous in improving coronary anastomoses during MID-CAB, but long-term anastomotic strength and histologic evaluation need to be investigated.
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Affiliation(s)
- A B Phillips
- Department of Cardiothoracic Surgery, New York Hospital-Cornell University Medical Center, New York 10021, USA
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Abstract
BACKGROUND AND OBJECTIVES To improve minimally invasive direct coronary artery bypass surgery (MID-CAB), new techniques of vascular anastomosis that are faster and more reliable need to be developed. STUDY DESIGN/MATERIALS AND METHODS Common carotids in a canine model were transected and an end-to-end anastomosis was performed by using one of four techniques (1) continuous 6-0 polypropylene closure (suture; n=6), (2) vascular clip (VCS; n=6), laser welding using 50% albumin solder with (3) a 1.32-micro laser (1.32las; n=6), and (4) a 1.9-micro diode laser (1.9las; n=4). Times for anastomosis (TA) were compared between groups by t-test. Pressures at which anastomosis failed (leak point pressure, LPP) were determined and compared by analysis of variance. RESULTS TA was faster for 1.32las and 1.9las at 8.4+/-0.7 and 7.8+/-0.3 min, respectively, when compared with suture at 13.8+/-1.0 min (P=0.001, confidence interval [CI]-8.1, -2.6 for 1.32las and CI -8.9, -3.1 for 1.9las). There was no statistical difference between VCS (8.3+/-3.3 min) and any other group (P > 0.17). LPPs (mm Hg) were similar for all groups: 350+/-37 for 1.32las, 280+/-31 for 1.9las, 347+/-46 for suture, and 358+/-53 for VCS, P=0.68. CONCLUSIONS In this study, laser welding using 50% human albumin solder resulted in faster anastomotic times. Anastomoses were equivalent to conventional sutured anastomoses in failing at similar pressures. Laser welding using human albumin solder may be advantageous in improving coronary anastomoses during MID-CAB, but long-term anastomotic strength and histologic evaluation need to be investigated.
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Affiliation(s)
- A B Phillips
- Department of Cardiothoracic Surgery, New York Hospital-Cornell University Medical Center, New York 10021, USA
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Newton RW, Webster PA, Binu PS, Maskrey N, Phillips AB. Psychosocial stress in pregnancy and its relation to the onset of premature labour. Br Med J 1979; 2:411-3. [PMID: 486966 PMCID: PMC1595651 DOI: 10.1136/bmj.2.6187.411] [Citation(s) in RCA: 174] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A modified life events inventory was presented over a four-month period to 132 consecutive women going into spontaneous labour in Hull and Manchester. Three study groups were identified according to the duration of pregnancy. The levels of psychosocial stress in pregnancy were found to be particularly high in the mothers whose babies were born preterm. Stressful events may precipitate preterm labour in some women. The concept of antenatal care may have to be broadened if the incidence of premature labour and resulting perinatal mortality are to be reduced.
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