Hasselt University, Belgium.
Prof. Koen Vandewal, Hasselt University, Belgium.
Charge transfer (CT) states at the interface between electron-donating and electron-accepting (A) materials in organic thin films are characterized by absorption and emission bands within the optical gap of the interfacing materials. Depending on the used donor and acceptor materials, CT states can be very emissive, or generate free carriers at high yield. The former can result in rather efficient organic light emitting diodes (OLED), via thermally activated delayed fluorescence, while the latter property is exploited in organic photovoltaic (OPV) devices and photodetectors. In this talk, I will discuss the fundamental properties of CT states, with focus on high and low-frequency vibrational modes, and link them to organic solar cell performance. Furthermore, using a new device architecture, we introduce strong light-matter coupling, resulting in redshifted and steepened absorption edges, as well as reduced energy losses in photovoltaic devices.
Biography
Prof. Dr. Koen Vandewal obtained his PhD in Physics at Hasselt University in 2009 on the physics of organic photovoltaics. After that, he has been working for two years as a Postdoctoral Fellow at Linkoping University in Sweden and another two years at Stanford University in the US. From 2014 – 2018, he held an endowed professor position at the Technische Universitaet Dresden in Germany. In 2018, he took up a professor position at Hasselt University, where his is leading a research group which aims to solve fundamental questions in the field of organic and molecular electronics with relevance to applications in opto-electronic devices such as organic light-emitting diodes, organic solar cells and sensors. In the organic electronics community, he is best known for his seminal work on charge-transfer states at organic interfaces and their role in photovoltaic devices.