Nano-ribbon solar fuel devices

Energy generated from environmentally friendly, cost-effective solar cells offers a sustainable solution to meet the increasing global energy demand. Hence, researchers are focused on the development of thin-film solar cells using highly efficient, environmentally friendly, earth-abundant absorber materials like metal sulfides and selenides. Compared to other emerging compounds, antimony selenide (Sb2Se3) has gained tremendous interest as a promising photoactive material in photovoltaics due to its advantages of simplified phase chemistry, high physiochemical stability, suitable bandgap, high carrier mobility, and high absorption coefficient.

Different physio-chemical methods are used to generate Sb2Se3 thin films, which include rapid thermal evaporation (RTE), magnetron sputtering, close-spaced sublimation, electrodeposition, atomic layer deposition, etc. When the Sb2Se3 thin films are deposited onto a substrate, the (Sb4Se6)n ribbons exhibit different growth orientations (lateral and vertical growth modes) which are difficult to control due to their complex microstructures. In the (Sb4Se6)n 1D chain structure, the atoms are covalently bonded, whereas ribbons are interconnected by van der Waals forces. This results in faster migration of carriers along (Sb4Se6)n ribbons than between ribbons. In order to provide improved charge transport and to reduce the charge recombination throughout the Sb2Se3 layer, the ribbons should oriented perpendicular to the substrate. Therefore, it is crucial to regulate the ratio of lateral and vertical growth of (Sb4Se6)n ribbons in Sb2Se3 thin films to ensure efficient carrier transport. Thus, this study focuses to explore novel growth conditions for optimal Sb2Se3 nanoribbon orientation for efficient solar cells.

In order to analyze the preferred orientation of 1D nanoribbons, the Sb2Se3 will be deposited onto the fluorine-doped tin oxide (FTO) substrates with the use of RTE. To understand the growth mechanism and carrier transport behavior of Sb2Se3 thin films, the structure, and properties of Sb2Se3 thin films will be systematically characterized and analyzed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, surface profilometer, and Kelvin probe force microscopy.

Moreover, Sb2Se3 thin films on solar cell performance will be investigated. Herein the thin-film solar cells devices are configured in superstrate configuration where the thin film is coated with a buffer layer and then ends with the deposition of metallic back-contact (i.e., Au). The buffer used in this study to form a p-n heterojunction with an absorber layer is n-type TiO2. The photo-generated electrons then move from Sb2Se3 (p-type) to TiO2 (n-type) due to the creation of a built-in electric field at the p-n heterojunction between the Sb2Se3/TiO2 interface. On the other hand, the photo-generated holes are attracted by the p-type hole-transport layer and collected by the Au which will reduce the recombination at the back contact. Finally, the effect of the modified thin films will be used to fabricate efficient water splitting devices.

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.