Abstract
Co3O4-based spinels are a new class of wide-band-gap p-type conductive oxides with high work functions. We examined the structures, conductivities, work functions, and optical spectra of quaternary Zn-Ni-Co-0 thin films across the entire spinel region of the ZnO-NiO-Co3O4 diagram using a high-throughput combinatorial approach. We found that the conductivity of as-deposited films is maximized (100 S/cm) and optical absorption (at 1.8 eV) is minimized in different regions of the diagram, while the work function of annealed films is high and relatively constant (5.8 ± 0.1 eV). These properties made Zn-Ni-Co-O thin films applicable as p-type interlayers in solar cells. As an example, amorphous Zn-Co-0 hole transport layers had good performance in bulk heterojunction organic photovoltaic devices.
Similar content being viewed by others
References
H. Kawazoe, M. Yasukawa, H. Hyodo, M. Kurita, H. Yanagi, and H. Hosono: P-type electrical conduction in transparent thin films of CuAlO2. Nature 389, 939 (1997).
H. Hosono, Y. Ogo, H. Yanagi, and T. Kamiya: Bipolar conduction in SnO thin films. Electrochem. Solid-State Lett. 14, H13 (2011).
H. Sato, T. Minami, S. Takata, and T. Yamada: Transparent conducting p-type NiO thin films prepared by magnetron sputtering. Thin Solid Films 236, 27 (1993).
H. Mizoguchi, M. Hirano, S. Fujitsu, T. Takeuchi, K. Ueda, and H. Hosono: ZnRh2O4: a p-type semiconducting oxide with a valence band composed of a low spin state of Rh3+ in a 4d6 configuration. Appl. Phys. Lett. 80, 1207 (2002).
J.F. Wager, D.A. Keszler, and R.E. Presley: Transparent Electronics Springer, New York, 2008).
J. Tate, P.F. Newhouse, R. Kykyneshi, P.A. Hersh, J. Kinney, D. H. McIntyre, and D.A. Keszler: Chalcogen-based transparent conductors. Thin Solid Films 516, 5795 (2008).
K. Ueda, H. Hiramatsu, M. Hirano, T. Kamiya, and H. Hosono: Wide-gap layered oxychalcogenide semiconductors: materials, electronic structures and optoelectronic properties. Thin Solid Films 496, 8 (2006).
O. Knop, K.I.G. Reid, R. Sutarno, and Y. Nakagawa: Chalkogenides of the transition elements. VI. X-ray, neutron, and magnetic investigation of the spinels CO3O4, NiCo2O4, Co3S4, and NiCo2S4. Can. J. Chem. 46, 3463 (1968).
K. Krezhov and P. Konstantinov: On the cationic distribution in zinc-cobalt oxide spinels. J. Phys: Condens. Matters, 9287 (1993).
R.R. Owings, G.J. Exarhos, C.F. Windisch, P.H. Holloway, and J.G. Wen: Process enhanced polaron conductivity of infrared transparent nickel-cobalt oxide. Thin Solid Films 483, 175 (2005).
M. Dekkers, G. Rijnders, and D.H.A. Blank: Znlr2O4, a p-type transparent oxide semiconductor in the class of spinel zinc-d6-transition metal oxide. Appl. Phys. Lett. 90, 021903 (2007).
S. Kim, J.A. Cianfrone, P. Sadik, K.-W. Kim, M. Mil, and D.P. Norton: Room temperature deposited oxide p-n junction using p-type zinc-cobalt-oxide. J. Appl. Phys. 107, 103538 (2010).
J.D. Perkins, T.R. Paudel, A. Zakutayev, P. Ndione, P.A. Parilla, S. Lany, D.S. Ginley, A. Zunger, N.H. Perry, T.O. Mason, J.S. Bettinger, Y. Shi, and M.F. Toney: Hole doping in ternary oxides: enhancing p-type conductivity in cobalt oxide spinels, unpublished.
J.D. Perkins, J.A. del Cueto, J.L. Alleman, C. Warmsingh, B.M. Keyes, L.M. Gedvilas, P.A. Parilla, B. To, D.W. Reade, and D.S. Ginley: Combinatorial studies of Zn-AI-O and Zn-Sn-O transparent conducting oxide thin films. Thin Solid Films 411, 152 (2002).
A. Zakutayev, T. Paudel, J. Perkins, S. Lany, A. Zunger, and D. Ginley: Cation off-stoichiometry leads to p-type self-doping and enhanced transparency in Co2ZnO4 and Co2NiO4 spinels, unpublished.
K.J. Kim and Y.R. Park: Optical investigation of charge-transfer transitions in spinel Co3O4. Solid State Commun. 127, 25 (2003).
Y. Tang, M.A. Grayson, N.H. Perry, T.O. Mason, P.F. Ndione, A. Zakutayev, J.D. Perkins, and D.S. Ginley, unpublished.
K.X. Steirer, J.P. Chesin, N.E. Widjonarko, J.J. Berry, A. Miedaner, D. S. Ginley, and D.C. Olson: Solution deposited NiO thin-films as hole transport layers in organic photovoltaics. Org. Electron. 11, 1414 (2010).
Acknowledgments
This research was supported as part of two Energy Frontier Research Centers funded by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences: Center for Inverse Design (CID) under Contract No. DE-AC36-08GO28308 to NREL (A.Z., J.D.P., D.S.G.) and Center for Interface Science: Solar-Electric Materials (CIS: SEM) under Award No. DE-SC0001084 (A.K.S., N.E.W., J. J.B.). P.A.P. received support from the US DOE Office of Energy Efficiency and Renewable Energy, Solar Energy Technology Program. A.Z., J.D.P., and D.S.G. would like to thank Tula Paudel, Stephan Lany, and Alex Zunger at NREL for numerous fruitful discussions. A.K.S., N.E.W., and J.J.B. thank Jennifer Leisch for initial work on amorphous ZnCoO.
A.Z. grew and characterized polycrystalline Zn-Ni-Co-O samples and wrote the paper with contributions, suggestions, and comments from J.D.P., P.A.P., N.E.W., A.K.S., J.J.B., and D.S.G. N.E.W., A.K.S., and J.J.B. were responsible for amorphous ZnCoO hole transport layer deposition, characterization, and OPV device fabrication/analysis. J.D.P. and P.A.P. assisted with automation of combinatorial data collection and automation of the analysis.
Author information
Authors and Affiliations
Corresponding author
Supplementary materials
Supplementary materials
For supplementary material for this article, please visit http://dx.doi.org/10.1557/mrc.2011.9
Rights and permissions
About this article
Cite this article
Zakutayev, A., Perkins, J.D., Parilla, P.A. et al. Zn-Ni-Co-O wide-band-gap p-type conductive oxides with high work functions. MRS Communications 1, 23–26 (2011). https://doi.org/10.1557/mrc.2011.9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1557/mrc.2011.9