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.
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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.
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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
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DOI: https://doi.org/10.1557/mrc.2011.9