Simulation and Fabrication of Defect Tolerant High Efficiency Epitaxial III-V Photovoltaics

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MEHROTRA-DISSERTATION-2014.pdf (4.01 MB)

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2014-08

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Abstract

The goal of this dissertation is to establish a pathway towards development of cost-effective high efficiency III-V photovoltaics. Combining the unsurpassed performance of GaAs based multi-junction technologies with a conventional cheap roll to roll processing standards of thin film industry could lead to paradigm-shifting reduction of the cost of solar electricity. Growth of III-V on polycrystalline flexible substrates provides a path towards this goal, but is limited by high dislocation densities, which leads to minimal efficiency using conventional device designs. In this work we will focus on strategies for development of thinner (reduced process time) and more defect tolerant devices, that could deliver higher efficiencies on flexible substrates. This work has shown single crystalline like GaAs epilayers on polycrystalline flexible templates, and within this framework has demonstrated theoretically and experimentally possibility of increasing efficiencies by more than two folds than their conventional thin film counterparts (in presence of dislocations in excess of 10^8cm-2). Using defect tolerant designs for ultra-thin tandem design, efficiencies in excess of 25% can be achieved on flexible templates.

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Semiconductors, Solar cells, GaAs, III-V, Dislocations, Defects, Drift-diffusion model, Design optimization, Flexible substrates, Ultra-thin design, Tandem, Polycrytalline materials, MBE, Epitaxy, Photovoltaics

Citation

Portions of this document appear in: Freundlich, A., C. Rajapaksha, A. Alemu, A. Mehrotra, M. C. Wu, S. Sambandam, and V. Selvamanickam. "Single crystalline gallium arsenide photovoltaics on flexible metal substrates." In 2010 35th IEEE Photovoltaic Specialists Conference, pp. 002543-002545. IEEE, 2010. And in: Mehrotra, Akhil, Alex Freundlich, V. Selvamanickam, G. Majkic, R. Wang, and S. Sambandam. "Epitaxial growth of (100) GaAs on CeOx coated flexible metal substrates." In 2012 38th IEEE Photovoltaic Specialists Conference, pp. 002571-002574. IEEE, 2012. And in: Mehrotra, A., A. Freundlich, and A. Alemu. "Optimized device design for radiation resistant and high dislocation solar cells for space." In 2010 35th IEEE Photovoltaic Specialists Conference, pp. 002574-002577. IEEE, 2010. And in: Mehrotra, A., A. Alemu, and A. Freundlich. "Modeling and optimal designs for dislocation and radiation tolerant single and multijunction solar cells." In Physics and Simulation of Optoelectronic Devices XIX, vol. 7933, p. 79332G. International Society for Optics and Photonics, 2011. And in: Mehrotra, A., A. Alemu, and A. Freundlich. "Modeling of defect-tolerant thin multi-junction solar cells for space application." In Physics, Simulation, and Photonic Engineering of Photovoltaic Devices, vol. 8256, p. 82561H. International Society for Optics and Photonics, 2012. And in: Mehrotra, A., A. Alemu, and A. Freundlich. "Modeling of defect-tolerant thin multi-junction solar cells for space application." In Physics, Simulation, and Photonic Engineering of Photovoltaic Devices, vol. 8256, p. 82561H. International Society for Optics and Photonics, 2012. And in: Mehrotra, Akhil, and Alex Freundlich. "Superior radiation and dislocation tolerance of IMM space solar cells." In 2012 38th IEEE Photovoltaic Specialists Conference, pp. 003150-003154. IEEE, 2012. And in: Mehrotra, Akhil, and Alex Freundlich. "Increased radiation resistance of thin 4J-IMM solar cells by recycling transparency photon losses." In 2013 IEEE 39th Photovoltaic Specialists Conference (PVSC), pp. 2774-2778. IEEE, 2013. And in: Freundlich, Alex, Gopi K. Vijaya, and Akhil Mehrotra. "Superlattice intermediate band solar cell with resonant upper-conduction-band assisted photo-absorption and carrier extraction." In 2013 IEEE 39th Photovoltaic Specialists Conference (PVSC), pp. 1635-1638. IEEE, 2013. And in: Freundlich, Alex, Gopi K. Vijaya, and Akhil Mehrotra. "Superlattice intermediate band solar cell with resonant upper-conduction-band assisted photo-absorption and carrier extraction." In 2013 IEEE 39th Photovoltaic Specialists Conference (PVSC), pp. 1635-1638. IEEE, 2013. And in: Mehrotra, A., A. Alemu, and A. Freundlich. "Thin high efficiency defect-tolerant homo-type GaAs tandem design." In 2011 37th IEEE Photovoltaic Specialists Conference, pp. 001601-001604. IEEE, 2011. And in: Freundlich, Alex, Akhil Mehrotra, Manori Gunasekera, Gilles Lancel, and Gopi Krishna Vijaya. "Ultra-thin defect tolerant high efficiency III–V tandems for development of low-cost photovoltaics." In 2014 IEEE 40th Photovoltaic Specialist Conference (PVSC), pp. 2117-2121. IEEE, 2014. And in: Mehrotra, Akhil, and Alex Freundlich. "Modeling of defect tolerance of IMM multijunction photovoltaics for space application." In Physics, Simulation, and Photonic Engineering of Photovoltaic Devices II, vol. 8620, p. 86200V. International Society for Optics and Photonics, 2013. And in: Mehrotra, Akhil, Gopi K. Vijaya, and Alex Freundlich. "Drift-diffusion modeling of a superlattice pin device with resonant conduction-band assisted photon absorption and carrier." In 2014 IEEE 40th Photovoltaic Specialist Conference (PVSC), pp. 1080-1083. IEEE, 2014. And in: Mehrotra, Akhil, Wei Wang, and Alex Freundlich. "Modeling and fabrication of GaAs solar cells with high dislocation tolerance." In 2014 IEEE 40th Photovoltaic Specialist Conference (PVSC), pp. 0514-0519. IEEE, 2014.

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https://hdl.handle.net/10657/4740

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