Proceedings of 13th Conference on Hybrid and Organic Photovoltaics (HOPV21)
Publication date: 11th May 2021
The fabrication of one-dimensional (nanotubes) and three-dimensional (nanotrees) transparent conducting oxides (TCOs) by scalable vacuum and plasma processes implemented in just one chamber is demonstrated in this work. The new method comprises the formation of organic nanowires serving as 1D and 3D soft templates, followed by the deposition of polycrystalline Indium Tin Oxide (ITO) layers by magnetron sputtering, and removal of the template under mild vacuum conditions. The process variables are tuned to control the stoichiometry, morphology, and alignment of the ITO nanotubes and nanotrees. As a result, high quality crystalline, semitransparent and conductive nanostructured layers particularly interesting for optoelectronic, energy harvesting and sensing applications.
Nanoprobe characterization reveals resistivities of individual nanotubes as low as 3.5 ± 0.9 x 10-4 Ω·cm, a value comparable to single-crystalline counterparts. The assessment of diffuse reflectance and transmittance in the UV-VIS range confirms the viability of the supported ITO nanotubes as random optical media working as strong scattering layers. Further ability to form ITO nanotrees opens the path for practical applications as ultra-broadband absorbers in the NIR. The demonstrated low resistivity and optical properties of these ITO nanostructures open the way for their use in optoelectronics, IR shield, energy harvesting, nanosensors, and photoelectrochemical applications. The process is generic and can be used for other TCOs and wide-bandgap semiconductors.
We thank the AEI-MICINN (PID2019-110430GB-C21 and PID2019-109603RA-I0), the Consejería de Economía, Conocimiento, Empresas y Universidad de la Junta de Andalucía (PAIDI-2020 through projects US-1263142, ref. AT17-6079, P18-RT-3480), and the EU through cohesion fund and FEDER 2014–2020 programs for financial support. JS-V thank the University of Seville through the VI PPIT-US and the Ramon y Cajal Spanish National programs. The projects leading to this article have received funding from the EU H2020 program under the grant agreements 851929 (ERC Starting Grant 3DScavengers) and 899352 (FETOPEN-01-2018-2019-2020 - SOUNDofICE).