Development of silicon heterojunction solar cells. Energy, Solar Technology

Silicon solar cells account for over 90% of an enormous worldwide market, and silicons fundamental properties means it is likely to be a major technology for many years to come. The traditional approach to fabricating a silicon solar cell involves at least one high temperature (>800 degrees Celsius) diffusion step to form a p-n junction. Such high temperature processes are relatively expensive and can result in process contamination. An alternative approach is to use a heterojunction architecture, which involves depositing materials with different bandgaps on the substrate. This can result in solar cells with higher efficiencies than conventional diffusion-based solar cells. Depositions can also be performed at relatively low temperatures and hence this may result in a lower fabrication cost.

This PhD project aims to perform underpinning work necessary to develop a new area of research for the UK. We aim to develop low cost processing routes to fabricate silicon heterojunction cells. Novel deposition processes will be investigated and novel materials for the transparent conducting electrodes will be explored. Test cell structures will be characterised using a suite of techniques available in Warwick, including quasi-steady-state photo conductance, photoluminescence imaging, and capacitance-voltage measurements. Processing will be optimised to minimise interface trap densities and to produce carrier-selective contacts. Fundamental knowledge will be gained on the recombination of carriers at interfaces, and the physics of carrier-selective contacts. The long-term aim of the research area is to produce a higher efficiency lower cost silicon-based solar cell than at present. It is expected that such a structure, once successfully optimised, may find a future use as a base cell for a silicon-based tandem cell, perhaps in combination with a perovskite top cell.

This project aligns to EPSRC's Energy theme and the priority areas of Materials Technologies, Materials Characterisation, and Solar. The student will work closely with team members funded under the EPSRC SuperSilicon PV project (EP/M024911/1) and will use equipment already funded by EPSRC under grant EP/J01768X/2. The student will become part of the UKs PV community via the Supergen Solar Hub.