Electronic and optical properties modification of complex oxide epitaxial films and superlattices for efficient light harvesting
EMSL Project ID
47862
Abstract
We propose an aggressive program of epitaxial film synthesis, detailed and definitive materials characterization, optical and electronic properties measurements and ab initio simulations with the goal of preparing complex oxide multilayers that could be very useful for advanced solar energy applications. The overall goal of this proposal is to test the hypothesis that the photoconductive properties of complex oxides of the form LaMO3, where M = Cr, Fe and Mn, can be tailored for efficient solar light harvesting by Sr doping on the A site, mixing and matching the transition metal cations (M) on the B site, and N doping the anion site. More specifically, we seek to answer the following questions: (i) Is the mechanism of conductivity in epitaxial films different from that in polycrystalline samples? (ii) Can the tetragonal distortion resulting from imperfect lattice matching be used to tune functional properties? (iii) Can carrier lifetimes be enhanced by chemical ordering on the A and B sites? (iv) Can the electronic structure of the internal interfaces resulting from chemical ordering be tailored to enhance photo-induced transport? We will use MBE to prepare compositionally and structurally well-defined crystalline films in four forms: (i) random solid solutions of SrxLa1-xMO3, (ii) digital superlattices of the form (LaMO3)n/(SrMO3)m, (iii) solid solutions of LaM1-yM'yO3, where M and M' are different transition metals, and, (iv) digital superlattices of the form (LaMO3)n/(LaM´O3)m. We will use the EMSL characterization tools STEM/EELS, RBS, XRD, APT and AFM to determine volume averaged and local structural parameters as well as composition, and draw meaningful correlations with data from optical absorption, photoconductivity, and electrical transport data. We will also carry out first-principles calculations of the band structures and optical absorption spectra for these various structures, in order to more quantitatively understand our experimental data. The impact of this work is that it could give us a new set of sustainable materials for photovoltaic energy generation and photoelectrochemical organic waste destruction with all the attendant benefits for both clean energy and green chemistry. The identified EMSL resources are needed to: (i) facilitate the synthesis and adequate characterization of materials that are inherently complex and difficult to make by virtue of their detailed atomistic structures, (ii) measure the optical, electronic and photochemical properties of these materials, and, (iii) accurately calculate from first principles the structural and electronic properties of these materials in order to understand them in detail, and guide future experimental efforts.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2013-10-01
End Date
2014-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Chambers SA. 2014. "Probing perovskite interfaces and superlattices with x-ray photoemission spectroscopy." In Hard X-ray Photoelectron Spectroscopy, ed. J. Woicik. No publisher listed. [In Press]
Choquette AK, R Colby, EJ Moon, CM Schleputz, MD Scafetta, DJ Keavney, and SJ May. 2015. "Synthesis, Structure, and Spectroscopy of Epitaxial EuFeO3 Thin Films." Crystal Growth & Design. doi:10.1021/cg501403m
Comes RB, P Sushko, SM Heald, RJ Colby, ME Bowden, and SA Chambers. 2014. "Band-Gap Reduction and Dopant Interaction in Epitaxial La,Cr Co-doped SrTiO3 Thin Films." Chemistry of Materials 26(24):7073-7082. doi:10.1021/cm503541u
Devaraj A, M Gu, RJ Colby, P Yan, CM Wang, J Zheng, J Xiao, A Genc, J Zhang, I Belharouak, D Wang, K Amine, and S Thevuthasan. 2015. "Visualizing Nanoscale 3D Compositional Fluctuation of Lithium in Advanced Lithium-Ion Battery Cathodes." Nature Communications 6:Article No. 8014. doi:10.1038/ncomms9014
Du Y, M Gu, T Varga, C Wang, ME Bowden, and SA Chambers. 2014. "Strain Accommodation by Facile WO6 Octahedral Distortion and Tilting During WO3 Heteroepitaxy on SrTiO3(001)." ACS Applied Materials & Interfaces. doi:10.1021/am5035686
Li G, T Varga, P Yan, Z Wang, CM Wang, SA Chambers, and Y Du. 2015. "Crystallographic Dependence Of Photocatalytic Activity For WO3 Thin Films Prepared By Molecular Beam Epitaxy." PNNL-SA-108744, Pacific Northwest National Laboratory, Richland, WA. [Unpublished]
Smith CR, AC Lang, V Shutthanandan, ML Taheri, and SJ May. 2015. "Effects of cation stoichiometry on electronic and structural properties of LaNiO3." Journal of Vacuum Science & Technology A 34:5. doi:10.1116/1.4922346
Wang Y, RB Comes, S Kittiwatanakul, SA Wolf, and J Lu. 2015. "Epitaxial niobium dioxide thin films by reactive-biased target ion beam deposition." Journal of Vacuum Science and Technology A--Vacuum, Surfaces and Films 33(2):021516. doi:10.1116/1.4906143