The Photon Day 2022

Program

9.45 Coffee and buns
10.15 Welcome and introduction
10.20 Håkan Rensmo (UU): Understanding solar cell materials – new possibilities with x-ray based spectroscopies
10.50 Ida Källquist (UU), winner of the 2022 "Uppsala Photon Science Award”: Operando photoelectron spectroscopy for the study of Li-ion batteries
11.30 Sebastian Westenhoff (UU): Understanding the eyes of plants, bacteria and fungi.

Understanding solar cell materials – new possibilities with x-ray based spectroscopies

Generally optoelectronic devices, such as solar cells, are composed of a number of different materials each with specific properties that may be tailored by controlling composition, structure, morphology and dimension. This complexity inevitably requires each individual component to be understood in the bulk limit, as well as in terms of its interaction with the other components, i.e. interfaces become crucial. Ideal tools for such chemical and electronic structure characterization at an atomic level are spectroscopies using X-rays. The presentation will cover new opportunities with x-ray based spectroscopies for investigating solar cell materials ranging from fundamental studies of materials to studies on systems in operando.

Operando photoelectron spectroscopy for the study of Li-ion batteries

Understanding the electrochemical reactions occurring inside a Li-ion battery (LIB) is crucial to further develop this technology and allow for greener and more sustainable energy solutions. In order to do this, there has long been a strive towards developing operando techniques, which allow for probing the battery during operation, and under more realistic conditions compared to post mortem studies (after battery cycling). Operando studies, in theory, allow for studying the reactions of the battery materials as they are happening, and can shed light on the kinetics of the many different reactions occurring at the LIB interfaces. This can in turn give valuable knowledge for how to optimize the battery performance, for example by tuning the interfacial properties. However, performing operando measurements often involve several practical challenges, including designing a suitable cell, developing a working methodology and understanding the effects the method/technique has on the processes one is trying to study. In this regard, performing operando measurements is rarely a straightforward task, and a lot of effort can be necessary in order to setup a working experiment. In this presentation I will highlight and discuss both the possibilities and challenges of performing operando photoelectron spectroscopy studies on LIBs, and in addition give some examples of recent results gained from studies performed at the HIPPIE beamline at MAX IV.

Understanding the eyes of plants, bacteria and fungi

We have eyes to perceive our surroundings. Lower organisms, like plants, bacteria and fungi do not have eyes, but use photoreceptor proteins instead. Phytochromes are red/far-red light photoreceptor proteins, which control a wide variety of functions in these organisms. I will discuss the structure of phytochromes with a special focus on how the proteins archive signaling. The studies shine light on the chemical mechanism of how phyotchromes perceive light for optimal growth, movements, or reproduction in lower organisms.