Epitaxial Electrodeposition of Hole Transport CuSCN Nanorods on Au(111) at the Wafer Scale and Lift-Off to Produce Flexible and Transparent Foils
The wide bandgap p-type metal pseudohalide semiconductor copper(I) thiocyanate (CuSCN) can serve as a transparent hole transport layer in various opto-electronic applications such as perovsksite and organic solar cells and light-emitting diodes. The material deposits as one-dimensional CuSCN nanorod arrays, which are advantageous due to their high surface area and good charge transport properties. However, the growth of high-quality epitaxial CuSCN nanorods has remained a challenge. Here, we introduce a low cost and highly scalable room temperature procedure for producing epitaxial CuSCN nanorods on Au(111) by an electrochemical method. Epitaxial CuSCN grows on Au(111) with a high degree of in-plane as well as out-of-plane order with +0.22% coincidence site lattice mismatch. The phase of CuSCN that deposits is a function of the Cu2+/SCN- ratio in the deposition bath. A pure rhombohedral material deposits at higher SCN- concentrations, whereas a mixture of rhombohedral and hexagonal phases deposits at lower SCN- concentrations. A Au/epitaxial CuSCN/Ag diode has a diode quality factor of 1.4, whereas a diode produced with polycrystalline CuSCN has a diode quality factor of 2.1. A highly ordered foil of CuSCN was produced by epitaxial lift-off following a triiodide etch of the thin Au substrate. The 400 nm-thick CuSCN foil had an average 94% transmittance in the visible range and a 3.85 eV direct bandgap.
B. Luo et al., "Epitaxial Electrodeposition of Hole Transport CuSCN Nanorods on Au(111) at the Wafer Scale and Lift-Off to Produce Flexible and Transparent Foils," Chemistry of Materials, vol. 34, no. 3, pp. 970 - 978, American Chemical Society, Feb 2022.
The definitive version is available at https://doi.org/10.1021/acs.chemmater.1c02694
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08 Feb 2022
U.S. Department of Energy, Grant DE-FG02-08ER46518