Low cost nanostructured antimony selenide for embedded energy systems

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Increasingly, small portable/remote systems, from biosensors in medical applications to "internetof things" in urban environments, require sustainable high yield off-grid energy autonomy. Designflexibility and low cost materials need to be an integral part for consideration in such embeddedenergy systems. Photons offer a suitable and widely available source of energy, which can beefficiently collected, manipulated and guided down to sub-micron scale. Antimony Selenide(Sb2Se3) is an emerging Earth abundant material with very good photovoltaic (PV) characteristics(i.e. high optical absorption coefficient and near optimum band gap). Sb2Se3 crystals grow inribbon-like structures resulting in 1D structures with improved carrier transport along the [001]direction, it is however reported that performance of such PV devices are limited by defects. It canbe envisaged that by forming a self-assembled nanostructure array, a photonic crystal, such asusing zinc oxide nanorods, light can be efficiently distributed towards a conformal extremely thinabsorber with the benefit of increased collection area and reduced requirement on the electrondiffusion length.At Northumbria University, planar PV devices based on Sb2Se3 materials are routinely fabricatedby thermal evaporation with ~2.8% conversion efficiency, forming a baseline device. In thisproject, an alternative low cost fabrication process will be developed based on hydrothermal oralternative solution based processes, to produce nanostructured materials (i.e. nanoparticles,nanowires or nanotubes). This method will ensure decoupling of the absorber materialsfabrication from its conformal deposition onto non-planar substrates (e.g. pre-formed photoniccrystals onto optical waveguide). Surface carrier recombination reduction will be studied throughinterface engineering via the deposition of monolayer oxides by ALD (e.g. TiO2 or Al2O3). Toensure high density of photons are reaching the absorber material, suitable optics and opticalwaveguides system will be designed. A comparison in performance will be made in a range ofembedded energy system, between theoretical (e.g. COMSOL) and experimental designedprototypes.