Exploring nanostructured light absorbers: from optoelectronics to innovative photovoltaics

Dr Thomas Macdonald
Research Fellowship 2019

Dr Thomas Macdonald
Imperial College London

Over 50 % of the electricity in the United Kingdom is generated through non-sustainable fossil fuels. This reliance on fossil fuels is leading to supply risks and is contributing strongly to carbon dioxide emissions, which is one of the primary causes of global warming. Tackling climate change by decoupling from carbon is essential in order to prevent pervasive and long-lasting damage to the earth’s climate and ecosystems.

Sunlight is our largest energy source and it delivers more energy to the earth in one hour than humanity consumes in a year. Harvesting sunlight can be achieved using photovoltaics where it is converted to electricity which can be used to power our homes, workplaces, and cities. In addition, solar power can also be stored (e.g. batteries) and used as and when required. Currently, the most effective way to convert sunlight into electricity is achieved through silicon photovoltaics (PVs), an established technology which has almost reached its maximum theoretical efficiency.

 

“Sunlight delivers more energy to the earth in one hour than humanity consumes in a year."

However, the fabrication of silicon PVs is non-trivial, and the end product is brittle and lacks electronic tunability. Perovskites are an emerging class of light absorber material for PVs and have the potential to achieve higher efficiency than silicon PVs. Moreover, they can be fabricated at low temperatures on flexible substrates and is therefore compatible with low cost and scalable roll-to-roll production methods. Despite this potential, the coexistence of both an efficient and stable perovskite solar cell remains elusive. In order to simultaneously maintain high efficiency and stability, both the chemistry of the perovskite materials along with interfacial engineering must be fully understood.

My project will investigate a variety of perovskite device architectures with an emphasis on understanding their surface chemistry as well as the interfacial interaction between the light absorbing materials and counter electrode upon exposure to light, oxygen and humidity. In particular, novel experimental techniques that will facilitate the measurement of charge carrier dynamics at both the surface of the materials, as well as at the interface, will be studied for the first time. This project will provide new design rules to guide the development of efficient and stable devices.