Carrier Selective Layers: Enabling the True Potential of Nanostructured Photovoltaics

I aim to demonstrate light weight, flexible solar cells with high efficiency to cost ratio using compound semiconductors for niche applications like wearable electronics and un-manned, light weight drones.

High power conversion efficiency in solar cells can be achieved by controlling the (i) light absorption and emission characteristics of the absorber and (ii) separation of photo-generated electron-hole pairs, to generate current. Nanotechnology has emerged as a powerful tool to control the light-semiconductor interaction and nanostructured semiconductors with absorption and emission characteristics suitable for high efficiency solar cells have already been demonstrated. Nanostructured semiconductors also reduce the volume of semiconductor material required for high efficiency solar cells, providing a pathway to light weight and flexible devices.

Charge separation and extraction from these nanostructured semiconductors is currently limiting the efficiency of nanostructured solar cells. Conventionally, a p-n junction is used to separate photo-generated electrons and holes in a solar cell. It is, however, very challenging to form good quality p-n junctions in nanostructures. In this project, I propose a novel mechanism for charge extraction from nanostructures that eliminates the need to form p-n junctions, to achieve the high power conversion efficiencies promised by nanostructured solar cells.

This project will benefit research communities worldwide interested in nanostructured photovoltaics or the third-generation photovoltaic technologies and is the first step towards establishing a new research programme on nanostructured compound semiconductor photovoltaics in the UK.

In addition to uncovering fundamental physics at the nanoscale, this project paves the way towards sustainable and green energy generation by addressing the important issue of efficiency to cost ratio of photovoltaics. The technology developed during this project will generate intellectual property related to nanostructured PV. I will work with Cardiff University's commercial development team and Cardiff University's patent holding company, University College Cardiff Consultants Limited (UC3) to protect any IP resulting from this project. I will work with the recently established Institute for Compound Semiconductors (ICS) and Innovate UK's Advanced Materials, High Value Manufacturing and Compound Semiconductor Catapult (CSC) programmes to transfer the research outcomes to industry, creating technological jobs in the energy sector in the UK.

Advancement of fundamental science:
Development in nano-fabrication, characterisation and modelling tools over the last decade is fuelling rapid progress in the field of sustainable energy conversion and usage using nanotechnology. To realise nanostructure based efficient optoelectronic devices, we need to achieve fundamental understanding of the charge carrier dynamics in nanostructures and nanostructure based heterostructures. This project is designed to gain good understanding of the electronic behaviour of heterosturctures formed between semiconductor nanostructures and carrier selective layers. The scientific understanding of these phenomenon, developed during the project will be used to develop the technology for charge-carrier extraction strategies from nanostructures and fabrication of photovoltaic devices with the nanostructures.

Step out and 'game-changing' potential in the context of the current state-of-the-art:
Use of charge selective layers with III-V semiconductor nanostructures to enable efficient photo-generated carrier separation in devices for energy conversion is a dramatic departure from conventional devices currently being used. By exploring fundamental physics of such devices to enable high efficiency solar cells, this project opens a potential pathway for high efficiency devices with added functionalities. This project will develop and use nano-fabrication techniques that are compatible with current optoelectronic industry practices, to enable easy uptake of technology by the industry.

Implementation of new technology:
The concepts and technology developed during this project will be used for developing intellectual property. The technology developed during the project will be commercialised by starting a spin-off company in UK or by collaborating with UK companies like IQE plc. and innovate UK's Advanced materials, high value manufacturing and compound semiconductor catapult programmes.

Pathway towards sustainability and reduced greenhouse gas emissions:
The proposed research addresses the important issue of the efficiency to cost ratio of photovoltaic devices. The device concepts proposed here have the potential to bring down the cost/watt of III-V semiconductor photovoltaics generated electricity significantly and attain functionalities currently not available. The project will pave the way to a more sustainable world by promoting wider uptake of photovoltaics because of light weight and flexible devices that can be integrated into building and wearable products. The concepts for efficient energy generation proposed here will result in huge savings for the environment and the global economy, and eventually promote sustainable growth.

Strengthen intellectual capabilities in energy field in UK:
This project will help me set up a new programme on nanotechnology based photovoltaics at Cardiff University. I will effectively train the next generation of students and thought leaders in optoelectronics/photovoltaics research in UK through this new programme. My programme will position UK researchers among the pioneering groups in nanostructured photovoltaic devices. My research programme will enable more photovoltaic devices with high efficiency to cost ratio.

Economic or social impact:
I expect the results of this project will spur further interests not just in the research communities but also from industry to invest in this area to develop the concepts and technologies demonstrated in the project. New photovoltaic technology will allow the industry to grow, creating high-technology jobs. UK will be well placed to take advantage of this because of its current investment drive in the field of compound semiconductors. In addition, the processing techniques developed in this project will provide a foundation for the development and refinement of the fabrication of nanostructured, flexible devices for the industry.