Graphene transparent conductors for tandem photovoltaic cells

Silicon photovoltaics is one of the most exciting and rapidly evolving industries worldwide. Not only can it reduce harmful greenhouse gas emissions from electricity generation, it is the most cost effective solution for electrification of many developing countries. In this project the student will work with a team of dedicated researchers on concepts to increase the performance and lower the cost of solar cells. One of the most exciting areas of research in photovoltaics at present is the development of "tandem cells". This concept uses two or more cells, stacked on each other, to exploit a larger amount of energy contained in the sunlight spectrum. A critical part of such cells is their interconnection via a transparent conducting electrode.

This project aims to demonstrate the control of conductivity in graphene as a result of electrostatic charge with the purpose of making an effective graphene transparent electrode. It involves transfer of CVD graphene onto specially designed dielectric substrates, which have a pre-arranged metal electrode configuration, and can be deposited/embedded with a concentration of static charge. The created devices will be measured to test sheet resistance and hall mobility, as a function of dielectric charge concentration. They will be also be characterised via advanced electron microscopy, scanning Kelvin Probe microscopy, impedance spectroscopy, and photoluminescence, and their properties tailored by controlling the synthesis of interfacial layers adjacent to the graphene. Demonstrating highly conductive graphene as a results of a charged dielectric remains a challenge in the field, and can enable its use as a transparent conductor in flexible electronics and tandem solar cells. The production of such devices is, as of yet, limited by the lack of a suitable transparent electrode. As such, this project falls within the EPSRC Energy and ICT research areas. The project concentrates on developing such ground-breaking concept, and applying it to the field of electronic and interface materials, via advanced methods in chemistry, solid state physics, and device characterization.