Low cost nanostructured antimony selenide for embedded energy systems

Increasingly, small portable/remote systems, from biosensors in medical applications to "internet
of things" in urban environments, require sustainable high yield off-grid energy autonomy. Design
flexibility and low cost materials need to be an integral part for consideration in such embedded
energy systems. Photons offer a suitable and widely available source of energy, which can be
efficiently 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 in
ribbon-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 can
be envisaged that by forming a self-assembled nanostructure array, a photonic crystal, such as
using zinc oxide nanorods, light can be efficiently distributed towards a conformal extremely thin
absorber with the benefit of increased collection area and reduced requirement on the electron
diffusion length.
At Northumbria University, planar PV devices based on Sb2Se3 materials are routinely fabricated
by thermal evaporation with ~2.8% conversion efficiency, forming a baseline device. In this
project, an alternative low cost fabrication process will be developed based on hydrothermal or
alternative solution based processes, to produce nanostructured materials (i.e. nanoparticles,
nanowires or nanotubes). This method will ensure decoupling of the absorber materials
fabrication from its conformal deposition onto non-planar substrates (e.g. pre-formed photonic
crystals onto optical waveguide). Surface carrier recombination reduction will be studied through
interface engineering via the deposition of monolayer oxides by ALD (e.g. TiO2 or Al2O3). To
ensure high density of photons are reaching the absorber material, suitable optics and optical
waveguides system will be designed. A comparison in performance will be made in a range of
embedded energy system, between theoretical (e.g. COMSOL) and experimental designed
prototypes.

ReNU's enhanced doctoral training programme delivered by three uniquely co-located major UK universities, Northumbria (UNN), Durham (DU) and Newcastle (NU), addresses clear skills needs in small-to-medium scale renewable energy (RE) and sustainable distributed energy (DE). It was co-designed by a range of companies and is supported by a balanced portfolio of 27 industrial partners (e.g. Airbus, Siemens and Shell) of which 12 are small or medium size enterprises (SMEs) (e.g. Enocell, Equiwatt and Power Roll). A further 9 partners include Government, not-for-profit and key network organisations. Together these provide a powerful, direct and integrated pathway to a range of impacts that span whole energy systems.

Industrial partners will interact with ReNU in three main ways: (1) through the Strategic Advisory Board; (2) by providing external input to individual doctoral candidate's projects; and (3) by setting Industrial Challenge Mini-Projects. These interactions will directly benefit companies by enabling them to focus ReNU's training programme on particular needs, allowing transfer of best practice in training and state-of-the-art techniques, solution approaches to R&D challenges and generation of intellectual property. Access to ReNU for new industrial partners that may wish to benefit from ReNU is enabled by the involvement of key networks and organisations such as the North East Automotive Alliance, the Engineering Employer Federation, and Knowledge Transfer Network (Energy).

In addition to industrial partners, ReNU includes Government organisations and not for-profit-organisations. These partners provide pathways to create impact via policy and public engagement. Similarly, significant academic impact will be achieved through collaborations with project partners in Singapore, Canada and China. This impact will result in research excellence disseminated through prestigious academic journals and international conferences to the benefit of the global community working on advanced energy materials.