Advent calendar - December 20th - Tim Faber

In the Zernike Institute Advent Calendar, we are presenting 24 short spotlights in December. In these specials, we highlight PhD students, postdocs, support staff and technicians of our research groups and team - providing a glimpse in their typical day at work. In Episode 20 meet Tim Faber, PhD student in the Physics of Novel Semiconductors and Devices group of Prof. Jan Anton Koster.

Hello there! I'm Tim and I work as a phd in the group of Prof. Koster on hot carrier solar cells. Our motivation for our work is simple: The efficiency of today's standard solar cell is fundamentally limited by the Shockley Queisser limit, which is around 23 %. This is not bad, however imagine if you could somehow overcome this limit. The way in which solar cells could be used in the energy transition would be transformative.

In order to do this one must think outside the box, as the current box is controlled by Shockley and Queisser. The most elegant solution proposed is the so-called hot carrier solar cell. A hot carrier solar cell device tries to extract the, by sunlight excited, carriers as fast as possible. This minimizes the loss of energy via heat. By doing so, a hot carrier solar cell could achieve efficiencies up to 50%!! For a successful hot carrier solar cell you need very special type of material as an active layer. This is where we come in. We use theory and simulations in order to fundamentally understand how a material should look, and what qualities it should possess, in order for it to be used in a hot carrier solar cell.

A typical day involves a lot of interaction between me and my computer. As simulations often take long, there is plenty of time for coffee, having (scientific) discussions with my supervisor, and engaging with fellow experimental phds (Primarily, my roommate Federico Ferrari, for whom I'm rooting to secure his spot on this calendar, as it symbolizes excellence and success in life.). As a theoretician, I used to consider it a privilege not having to work in the lab, staying comfortable, rested and warm. However, with the current heating policy in our building I sometimes find myself reevaluating my position. Our code models the carrier dynamics inside a solar cell. As we are the rulers of our simulations, we can look at each physical interaction separately, and identify how it impacts the carrier dynamics exactly. In this way we come closer and closer in designing a material that would be the ultimate hot carrier solar cell absorber.

Merry Christmas!