Name: Lopez, Rene
Title: Associate Professor
Contact
Office: Chapman 343
Email: rln@physics.unc.edu
Phone: 919 962 7216
Web page: http://www.physics.unc.edu/project/rln/
Background
Dr. Lopez obtained his Bachelor degree from the Monterrey Institute of Technology (Mexico), and his Master and Doctoral degrees from Vanderbilt University (USA). He worked at the Oak Ridge National Laboratory and Vanderbilt University before joining the Faculty of the University of North Carolina at Chapel Hill (USA). He currently heads a group that does research in optical materials. In particular, bio-inspired photonic structures for organic photovoltaics, dye sensitized solar cells, sensors and electro-chromic materials
Research

Optical materials, nanofabrication, photovoltaic devices.
http://research.physics.unc.edu/project/rln/

Publications:

BOOK CHAPTER

• A. Meldrum, R. Lopez, R.H. Magruder, L.A. Boatner, and C.W. White. Structure and Properties of Nanoparticles Formed by Ion Implantation pp.255-281 in Materials Science with Ion Beams (Topics in Applied Physics 116) edited by H. Bernas, Springer-Verlag (2009).

REFEREED ARTICLES IN JOURNALS

• Abay Gadisa, Travis Hairfield, Leila Alibabaei, Carrie L. Donley, Edward T. Samulski, Rene Lopez, “Solution Processed Al-Doped ZnO Nanoparticles/TiOx Composite for Highly Efficient Inverted Organic Solar Cells”, ACS Applied Materials & Interfaces accepted August (2013)

• Tumbleston, John; Gadisa, Abay; Liu, Yingchi; Collins, Brian; Samulski, Edward; Lopez, Rene; Ade, Harald, “Modifications in Morphology Resulting from Nanoimprinting Bulk Heterojunction Blends for Light Trapping Organic Solar Cell Designs”, ACS Applied Materials & Interfaces accepted July (2013)

• Hanlin Luo , Wenjing Song , Paul G. Hoertz , Kenneth Hanson , Rudresh Ghosh , Sylvie Rangan , M. Kyle Brennaman , Javier J. Concepcion , Robert A. Binstead , Robert Allen Bartynski , Rene Lopez, and Thomas J. Meyer, A Sensitized Nb2O5 Photoanode for Hydrogen Production in a Dye-Sensitized Photoelectrosynthesis Cell, Chem. Mater., 25 (2), pp 122–131 (2013) DOI: 10.1021/cm3027972

• Yingchi Liu, Cary Tippets, Christoph Kirsh, Sorin Mitran, Edward T. Samulski, and Rene Lopez Balance between Light Trapping and Charge Carrier Collection: Electro-photonic Optimization of Organic Photovoltaics with Ridge-patterned Back Electrodes, J. Appl. Phys. 113, 244503 (2013); doi: 10.1063/1.4812235

• Ok, Myoung-Ryul; Ghosh, Rudresh; Brennaman, M.; Lopez, Rene; Meyer, Thomas; Samulski, Edward “Surface Patterning of Mesoporous Niobium Oxide Films for Solar Energy Conversion”, ACS applied Materials and Interfaces, (2013)

• Christin Lundgren, Kathleen Melde, Joan Redwing, Rene Lopez, “FDTD modeling of solar energy absorption in silicon branched nanowires”, Optics Express. Vol.21,No.S3, pp. A392–A400 (2013) DOI:10.1364/OE.21.000392

• Leila Alibabaei , Hanlin Luo , Ralph L. House , Paul G. Hoertz , Rene Lopez and Thomas J. Meyer “Applications of metal oxide materials in dye sensitized photoelectrosynthesis cells for making solar fuels: let the molecules do the work”, J. Mater. Chem. A, 2013, 4133-4145 Advance Article DOI: 10.1039/C2TA00935H

• Mukti Aryal, Doo-Hyun Ko, John R. Tumbleston, Abay Gadisa, Edward T. Samulski, and Rene Lopez “Large area nanofabrication of butterfly wing’s three dimensional ultrastructures” Journal of vacuum Science and Technology B 30, 061802 (2012)

• Yingchi Liu, Christoph Kirsh, Abay Gadisa, Mukti Aryal, Sorin Mitran, Edward T. Samulski, and Rene Lopez “Effects of nano-patterned versus simple flat active layers in upright organic photovoltaic devices” Journal of Physics D: Applied Physics 46 024008 (2012) doi:10.1088/0022-3727/46/2/024008

• Rudresh Ghosh, Yukihiro Hara, Leila Alibabaei, Kenneth Hanson, Sylvie Rangan, Robert Bartynski, Thomas J. Meyer and Rene Lopez “Increasing photocurrents in dye sensitized solar cells with tantalum doped titanium oxide photoanodes obtained by laser ablation” ACS Applied Materials and Interfaces 4 (9), pp 4566–4570 (2012) DOI: 10.1021/am300938g

• Abay Gadisa, Yingchi Liu, Edward T. Samulski, and Rene Lopez “Role of Thin n-Type Metal-Oxide Interlayers in Inverted Organic Solar Cells” ACS Applied Materials and Interfaces 4(8):3846-3851 (2012)

• Kenneth Hanson, M. Kyle Brennaman, Akitaka Ito, Hanlin Luo, Wenjing Song, Kelsey A. Parker, Rudresh Ghosh, Michael R. Norris, Christopher R. K. Glasson, Javier J. Concepcion, Rene Lopez, and Thomas J. Meyer “Structure–Property Relationships in Phosphonate-Derivatized, RuII Polypyridyl Dyes on Metal Oxide Surfaces in an Aqueous Environment”, J. Phys. Chem. C, 116 (28), pp 14837–14847 (2012) DOI: 10.1021/jp304088d

• D. Brosnan, R. Ghosh, L.E. McNeil, Rene Lopez, “Influence of ionic pretreatment on the performance of solid electrolyte dye-sensitized solar cells” Solar Energy, 89:9, 2312–2317 (2012).

• Abay Gadisa, Yingchi Liu, Edward T. Samulski, Rene Lopez, “Minimizing interfacial losses in inverted organic solar cells comprising Al-doped ZnO” Applied Physics Letters, 100, 253903, 4 pages, (2012) http://dx.doi.org/10.1063/1.4729861

• Abay Gadisa, Doo-Hyun Ko, John Tumbleston, Rene Lopez, Edward T. Samulski, “The role of solvent and morphology on miscibility of amethanofullerene and poly(3-hexylthiophene)” Thin Solid Films, Vol. 520, Issue 16, Pages 5466–5471, (2012)

• Kristen D. Alexander, Shunping Zhang,Angela High-Walker, Hongxing Xu, and Rene Lopez. “Relationship between Length and Surface-Enhanced Raman Spectroscopy Signal Strength in Metal Nanoparticle Chains: Ideal Models versus Nanofabrication” Journal of Nanotechnology, vol. 2012, Article ID 840245, 7 pages, (2012). doi:10.1155/2012/840245.

• John R. Tumbleston, Yingchi Liu, Edward T. Samulski, and Rene Lopez “Interplay Between Bimolecular Recombination and Carrier Transport Distances in Bulk Heterojunction Organic Solar”. Advanced Energy Materials, vol.2, issue 4, pages 477-486, (2012)

• B. Wu, A. Zimmers, H. Aubin, R. Ghosh, Y. Liu and R. Lopez. “Electric-field-driven phase transition in vanadium dioxide”, PRB rapid communications 84, 241410-1/241410-4, (2011).

• Rudresh Ghosh, Kyle Brennaman, Tim Uher, Myoung-Ryul Ok, Edward T. Samulski, Laurie E. McNeil, Thomas J. Meyer, Rene Lopez “Nanoforest Nb2O5 Photoanodes for Dye sensitized Solar Cells by Pulsed Laser Deposition” ACS Applied Materials and Interfaces 3, 3929–3935, (2011) (doi: 10.1021/am200805x)

• Doo-Hyun Ko , John R. Tumbleston, Abay Gadisa, Mukti Aryala,, Yingchi Liu, Rene Lopez, and Edward T. Samulski*, “Light-trapping nano-structures in organic photovoltaic cells” J. Mater. Chem., 21 (41), 16293 – 16303 (2011) (DOI: 10.1039/C1JM12300A)

• Emily Ray, Rene Lopez. “Numerical design and experimental realization of a metallo-dielectric metamaterial with the broadband coupling of propagating waves into plasmon modes in the visible range”, J. Optical Society of America B, vol. 28, No. 7 1778-1781 (2011)

• Doo-Hyun Ko, John R. Tumbleston, Kevin J. Henderson, Larken E. Euliss, Joseph M. DeSimone, Rene Lopez, and Edward T. Samulski, “Biomimetic microlens array with antireflective “moth-eye” surface” Soft-Matter 7,6404-6407 (2011) DOI: 10.1039/C1SM05302G

• A. Pashkin, C. KÄubler, H. Ehrke, R. Lopez, A. Halabica, R. F. Haglund, Jr., R. Huber, and A. Leitenstorfer,” Ultrafast Insulator-Metal Phase Transition in VO2 Studied by multi-THz Spectroscopy”, PRB 83, 195120/1-195120/9, (2011), DOI: 10.1103/PhysRevB.83.195120

• Yingchi Liu, Hubert Turley, John R. Tumbleston, Edward Samulski and Rene Lopez, Minority carrier transport length of electrodeposited Cu2O in ZnO/Cu2O heterojunction solar cells, Applied Physics Letters 98 162105/1-162105-3 (2011)

• Doo-Hyun Ko, John R. Tumbleston, Walter Schenck, Rene Lopez, Edward T. Samulski,”Photonic Crystal Geometry for Organic Polymer:Fullerene Standard and Inverted Solar Cells” J. Phys. Chem. C, 115 (10), pp 4247–4254 (2011)

• John R. Tumbleston, Doo-Hyun Ko, Edward T. Samulski, Rene Lopez, “Analyzing local exciton generation profiles as a means to extract transport lengths in organic solar cells” PRB 82, 205325/1-205325/10 (2010)

• Kristen D. Alexander, Kwan Skinner, Shunping Zhang, Hong Wei, and Rene Lopez “Tunable SERS In Gold Nanorod Dimers Through Strain Control On An Elastomeric Substrate” Nanoletters 10 (11), 4488–4493, (2010) DOI: 10.1021/nl1023172

• Doo-Hyun Ko, John Tumbleston, Myuong-Ryul Ok, Honggu Chun, Rene Lopez, Edward Samulski “Suppression of Bimolecular Recombination by UV-sensitive Electron Transport Layers in Organic Solar Cells”, Journal of Applied Physics 108, 083101/1-083101/6 (2010)

• John Tumbleston, Doo-Hyun Ko, Edward Samulski, Rene Lopez, “Non-ideal parasitic resistance effects in Bulk Heterojunction Organic Solar Cells”, Journal of Applied Physics 108, 084514/1-084513/8 (2010)

• R. Ghosh, M. Baker, R. Lopez, “Optical properties and aging of gasochromic WO3 thin films”, Thin Solid Films vol. 518, issue 8, 2247-2249 (2010)

• Stuart S. Williams, Scott Retterer, Rene Lopez, Ricardo Ruiz, Edward T. Samulski and Joseph M. DeSimone, “High-Resolution PFPE-based Molding Techniques for Nanofabrication of High-Pattern Density, Sub-20 nm Features: A Fundamental Materials Approach”, Nanoletters 10 (4), pp 1421–1428 (2009)

• K. D. Alexander, M. J. Hampton, S. Zhang, A. Dhawan, H. Xu and R. Lopez “A High Throughput Method For Controlled Hot Spot Fabrication in SERS-Active Dimer Arrays” Journal of Raman Spectroscopy 40, 2171–2175 (2009)

• E. A. Ray, M . J. Hampton and R. Lopez, “Simple demonstration of visible evanescent wave enhancement with far-field detection” Optics Letters 34, 2048-2050 (2009).

• Doo-Hyun Ko, John R. Tumbleston, Lei Zhanga, Stuart Williams, Joe DeSimone, Rene Lopez, Edward T. Samulski, “Photonic crystal morphology for organic solar cells” Nanoletters 9 2742-2746 (2009). Abstract also in Nature Photonic Literature hightlights: http://www.nature.com/nphoton/journal/v3/n8/full/nphoton.2009.128.html

• J.R. Tumbleston, D-H.Ko, E. T. Samulski and R. Lopez, ” Absorption and quasiguided mode analysis of organic solar cells with photonic crystal photoactive layers” Optics Express 17, 7670-7681 (2009)

• E. Donev, R. Lopez, L. C. Feldman, R. F. Haglund “Confocal Raman Microscopy across the Metal-Insulator Transition of Single Vanadium Dioxide Nanoparticles” Nanoletters 9, 702-706 (2009)

• J. R. Tumbleston, D.-H. Ko, E. T. Samulski, and R. Lopez, “Electro-photonic enhancement of bulk heterojunction organic solar cells through photonic crystal photoactive layer” Appl. Phys. Lett. 94, 043305-1/ 043305-3 (2009)

• A. Leitenstorfer, C. Kübler, R. Lopez, A. Halabica, R. F. Haglund, and R. Huber, “Ultrafast insulator-metal transition in VO2: interplay between coherent lattice motion and electronic correlations”, Phys. stat. sol. (c) 6, No. 1, 149–151 (2009).

• E. U. Donev, J. Y. Suh, R. Lopez, L. C. Feldman, and R. F. Haglund Jr., “Using a Semiconductor-to-Metal Transition to Control Optical Transmission through Subwavelength Hole Arrays,” Advances in OptoElectronics, vol. 2008, Article ID 739135, 10 pages, 2008. doi:10.1155/2008/739135

• C. Klubler, H. Ehrke, R. Huber, R. Lopez, R. Haglund Jr. Coherent structural dynamics and electronic correlations during an ultrafast insulator-to-metal phase transition in VO2. Phys. Rev. Lett. 99, 116401-1/116401-4(2007) Also selected for the September 24, 2007 issue of the Virtual Journal of Nanoscale Science and Technology.

• I. Karakurt, J. Boneberg, P. Leiderer, R. Lopez, A. Halabica, and R. F. Haglund, Jr., Transmission increase upon switching of VO2 thin films on microstructured surfaces. Appl. Phys. Lett. 91, 091907-1/ 091907-3 (2007)

• M.D. McMahon, D. Ferrara, C.T. Bowie, R. Lopez and R.F. Haglund Jr. Second harmonic generation from resonantly excited arrays of gold nanoparticles, Appl. Phys. B. 87, 259-265 (2007) http://www.springerlink.com/content/m4t21451m867rx16/

• P. U. Jepsen, B. M. Fischer, A. Thoman, H. Helm, J. Y. Suh, R. Lopez and R. F. Haglund, Jr. Metal-insulator phase transition in a VO2 thin film observed with terahertz spectroscopy, Physical Review B 74, 205103 (2006)

• J. Y. Suh, E. U. Donev, R. Lopez, L. C. Feldman and R. F. Haglund, Jr., Modulated optical transmission through subwavelength metal-VO2 hole arrays, Appl. Phys. Lett. 88, 133115-1/133115-3 (2006). Also selected for the April 10, 2006 issue of Virtual Journal of Nanoscale Science & Technology. http://www.vjnano.org

• E. U. Donev, J. Y. Suh, F. Villegas, R. Lopez, L. C. Feldman, and R. F. Haglund Jr., “Optical properties of subwavelength hole arrays in vanadium dioxide thin films, Phys. Rev. B rapid communications 73, 201401-1/201401-4 (2006). Also selected for the June 5, 2006 issue of Virtual Journal of Nanoscale Science & Technology. http://www.vjnano.org

• M. D. McMahon, R. Lopez, R. F. Haglund, Jr. Second-Harmonic Generation from Arrays of Symmetric Gold Nanoparticles, Phys. Rev. B rapid communications 73, 041401(R)/1-041401(R)/4 (2006). Also selected for the January 23, 2006 issue of Virtual Journal of Nanoscale Science & Technology. http://www.vjnano.org

• J. Rozen, R. Lopez, L. C. Feldman, R. F. Haglund, Two-dimensional current percolation in nanocrystalline vanadium dioxide thin films, Appl. Phys. Lett. 88, 081902-1/081902-3 (2006)

• M. D. McMahon, R. Lopez, H. M. Meyer III, L. C. Feldman, R. F. Haglund, Jr. Rapid Tarnishing of Silver Nanoparticles in Ambient Laboratory Air, Applied Physics B 80, 915-921 (2005)

• M. Rini, A. Cavalleri, R. Lopez, L. A. Boatner, R. F. Haglund jr. T. E. Haynes, L. C. Feldman, R. W. Schoenlein. Photoinduced Phase transition in VO2 Nanocrystals: Ultrafast Control of the Surface Plasmon Resonance, Optics Letters 30, 558-561 (2005)

• R. Lopez, L. C. Feldman, R. F. Haglund, Jr. Size dependent optical properties of VO2 nanoparticles in ordered arrays. Phys. Rev. Lett. 29, 177403-1/ 177403-4 (2004). Also selected for the Issue 18. V. 10 of the Virtual Journal of Nanoscale Science and Technology. http://www.vjnano.org

• R. Lopez, R. F. Haglund, Jr., L. C. Feldman, T. E. Haynes, L. A. Boatner, Optical nonlinearities in VO2 nanoparticles and thin films, Appl. Phys. Lett. 85, 5191-5193 (2004). Also selected for the January 2005 Issue of the Virtual Journal of Ultrafast Science. http://www.vjultrafast.org

• R. Lopez, T. E. Haynes, L. A. Boatner, L. C. Feldman and R. F. Haglund Jr. Switchable reflectivity on Silicon from composite VO2-SiO2 protecting layer. Appl. Phys. Lett. 85, 1410-1412 (2004)

• J. Y. Suh, R. Lopez, L. C. Feldman, R. F. Haglund, Jr. Semiconductor to metal phase transition in the nucleation and growth of VO2 nanoparticles and thin films, J. Appl. Phys. 96, 1209-1213 (2004).

• L. C. Feldman, G. Lupke, N. H. Tolk, R. Lopez, R. F. Haglund Jr., T. E. Haynes, L. A. Boatner, Particle-solid interactions and 21st century materials science. Nucl. Inst. and Met. Phys. Research B. 212, 1-7 (2003).

• R. Lopez, L. A. Boatner, T. E. Haynes, L. C. Feldman and R. F. Haglund Jr., Synthesis and characterization of size-controlled vanadium dioxide nanocrystal in a fused silica matrix. J. Appl. Phys. 92, 4031-4036 (2002).

• R. Lopez, T. E. Haynes, L. A. Boatner, L. C. Feldman and R. F. Haglund Jr., Temperature-controlled surface plasmon resonance in VO2 nanorods. Optics lett. 27, 1327-1330 (2002).

• R. Lopez, T. E. Haynes, L. A. Boatner, L. C. Feldman and R. F. Haglund Jr., Size effects in the structural phase transition of VO2 nanoparticles. Phys. Rev. B. 65, 224113-1/224113-5 (2002).

• R. Lopez, R. Ruiz, R.F. Haglund Jr., L.C. Feldman, Pulsed laser deposition of conductive metallo-dielectric optical filters. Appl. Phys. A 74, 307-310 (2002).

• R. Lopez, L. A. Boatner, T. E. Haynes, R. F. Haglund Jr. and L. C. Feldman, Enhanced hysteresis in the semiconductor-to-metal phase transition of VO2 precipitates formed in SiO2 by ion implantation. Appl. Phys. Lett. 79, 3161-3163 (2001).

REFEREED ARTICLES IN PROCEEDINGS

• Rudresh Ghosh, M. Kyle Brennaman, Javier J. Concepcion, Kenneth Hanson, Amar S. Kumbhar, Thomas J. Meyer, and René Lopez, “Efficient high surface area vertically aligned metal oxide nanostructures for dye-sensitized photoanodes by pulsed laser deposition”, Proc. SPIE 8109, 81090U (2011); doi:10.1117/12.893073

• J. R. Tumbleston, D.-H. Ko, E. T. Samulski, and R. Lopez, “Electro-Optical Model of Photonic Crystal Bulk Heterojunction Organic Solar Cells”, Proc. of the 2009 joint annual conference of the national society of black physicst and national society of Hispanic physicists. AIP Conference Proceedings 1280, 121-129, ISBN 978-0-7354-0830-2,(2010)

• John R. Tumbleston, Doo-Hyun Ko, Rene Lopez, and Edward T. Samulski, Characterizing enhanced performance of nanopatterned bulk heterojunction organic photovoltaics Proc. SPIE, Vol. 7047, 70470S (2008); DOI:10.1117/12.794823

• Rene Lopez, Richard F. Haglund, Jr., Leonard C. Feldman, Lynn A. Boatner, and Tony E. Haynes Optical nonlinearities and the ultrafast phase transition of VO2 nanoparticles and thin films. Proceedings SPIE Vol. 6118, 61180O-1/61180O-8 (2006)

• Matthew D. McMahon, Christopher T. Bowie, René Lopez, Leonard C. Feldman, and Richard F. Haglund Jr. Second harmonic generation from centrosymmetric arrays of gold nanoparticles. Proceedings SPIE Vol. 6106, 61061N-1/61061N-6 (2006)

• R. Lopez , L. C. Feldman, R. F. Haglund, Jr Fabricating arrays of vanadium dioxide nanodisks by FIB lithography and PLD Proceedings of SPIE – The International Society for Optical Engineering – Photon Processing in Microelectronics and Photonics III, 5339, 601-610 (2004).

• M. Rini, A. Cavalleri, R. Lopez, L. A. Boatner, R. F. Haglund jr. T. E. Haynes, L. C. Feldman, R. W. Schoenlein. Photoinduced Ultrafast control of a surface plasmon resonance via the insulator to metal phase transition in VO2 nanoparticles. Proceedings of 14th International Conference on ultrafast phenomena, 792-794 (2004)

• R. Lopez , R. F. Haglund, Jr. Ion beam lithography and fabrication ordered arrays of VO2 nanoparticles, Mat. Res. Soc. Symp. Proc. 820, R1.5.1-1/ R1.5.1-6 (2004)

• A.B. Hmelo, M.D. McMahon, R. Lopez, R.H. Magruder III, R.A. Weller, R.F. Haglund Jr. and L.C. Feldman, “Fabrication of Metallic Nanocrystal Arrays for Nanoscale Nonlinear Optics”, Ceramic Nanomaterials and Nanotechnology II, Ceramic Transactions V. 148, American Ceramic Society, 61-68, (2003).

• M. D. MacMahon, A. B. Hmelo, R. Lopez, W. T. Ryle, Allen T. Newton, Richard F. Haglund, L. C. Feldman, R. A. Weller, R. H. Magruder III. Fabrication of ordered Metallic nanocluster arrays using focused ion beam. Mat. Res. Soc. Symp. Proc. 739, 53-57 (2003).

• García-Llamas R, Gaspar-Armenta JA, Ramos-Mendieta F, López R., Haglund Jr. RF and Ruiz R: Injection of light into a planar dielectric wave guide of metallic walls. Proceedings of SPIE. 4439: 88-94 (2001)