Nanoscale Functional Imaging of Emerging Photovoltaic Materials

Event Date
Monday, 30 May 2022 - 2:00pm
Imperial College London

Dr Jae Sung Yun

Lecturer in Advanced Technology Institute, Department of Electrical and Electronic Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK

Hybrid Seminar: Click here to join the Seminar  

Venue: U1203, Uren Level 12 auditorium, WHite City Campus, Imperial College London

Abstract: In a semiconducting material, most forms of topological defects have undesirable electronic properties. Nanoscale defects can introduce localised regions of high charge-carrier recombination rates by introducing the extra energy levels into the band gap, thus reducing the overall minority carrier lifetime of the material. Therefore, it is critical to either eliminate or tune the properties of such nanoscale defects and understand their roles explicitly. This talk discusses the utilisation of cutting-edge scanning probe microscopy techniques such as photo-assisted conductive atomic force microscopy and scanning Kelvin probe force microscopy in emerging photovoltaic materials. I will present a demonstration of these techniques for 3D nanoscale imaging of a sample surface that reveals photovoltaic characteristics of grain boundaries, twins, and ferroic domains. In particular, the beneficial or detrimental role of grain boundaries by tuning chemical composition in halide perovskites and kesterites will be discussed that has an unforeseen impact on the charge transport properties. Also, I will present nano-IR and helium ion microscopy/secondary ion mass microscopy techniques that allow chemical compositional variation across the grain boundaries and ferroelastic domains in halide perovskites. Finally, my presentation will discuss future prospective strategies for tuning the local defect properties that could further boost the device performance.

 Bio: Dr Jae Sung Yun is a Lecturer in Energy Technology at the Advanced Technology Institute, Department of Electrical and Electronic Engineering, University of Surrey, UK. He graduated with a bachelor's degree in Materials Science and Engineering (MSE) at Yonsei University, Korea in 2008 and a Master of philosophy in MSE at the University of New South Wales, Australia in 2010. He was then awarded his PhD in silicon thin film solar cells under the supervision of Professor Martin Green in 2015, followed by a postdoc and a Lecturer at the School of Photovoltaic and Renewable Energy Engineering at the University of New South Wales, Australia. His research involves the development of emerging photovoltaic technologies and investigation of properties of nanoscale topological defects. He utilises scanning probe microscopy techniques to elucidate photovoltaic device performance limiting factors by correlating local topological defects such as grain boundaries to their electrical, chemical, and optoelectronic properties. His work has led to over 50 publications in peer-reviewed journals with citations over 3500.