NOTE: THIS SEMINAR WAS HELD ONLINE

Find it here: https://youtu.be/h-yy7oZgLmg

Welcome to the first ICN2 #StayAtHome Seminar!

By Prof. Anders Hagfeldt, Professor in Physical Chemistry at Laboratory of Photomolecular Science, Swiss Federal Institute of Technology Lausanne (EPFL), Switzerland

Abstract: In this talk I will overview the virtue of nanomaterials for solar energy conversion using as examples dye-sensitized (DSSC) and perovskite solar cells (PSC) as well as Cu2O photoelectrodes for hydrogen production.

Some years back my research group at Uppsala University, Sweden, introduced alkoxy functionalized donor groups as a building block in organic dyes as light harvesters for DSSC. This donor group provides a desirable 3-dimensional structure that aids in surface protection of electrons injected into the semiconductor from oxidants in the electrolyte, allowing for record-setting cobalt- and copper-based redox shuttles to be utilized more frequently. With these systems we recently set the world record efficiency for DSSC of 12.25%. DSSCs are ideally suited for ambient light and indoor applications where efficiencies up to 35% have been reached calculated with respect to the fluorescent light source.

In our work on perovskite solar cells (PSC) we have achieved efficiencies above 23% with a mixed composition of iodide/bromide and organic and inorganic cations. With the use of SnO2 compact underlayers as electron acceptor contacts we have constructed planar perovskite solar cells with a hysteresis free efficiency above 22%. Through compositional, engineering larger perovskite grains grown in a monolithic manner are observed and reproducibility and device stability are improved. With regards to lifetime testing, we have shown a promising stability at 85 oC for 500 h under full solar illumination and maximum power point tracking (95% of the initial performance was retained). Our present main directions of developing passivation interface layers and all-inorganic perovskite materials will be discussed in the lecture.

The state-of-the-art Cu2O photocathode employs gold as the back contact which, besides being expensive, can lead to considerable electron-hole recombination. Recently, we presented a Cu2O photocathode with overall improved performance, enabled by using solution-processed CuSCN as hole transport material. Owing to multiple advantages of applying CuSCN as the hole transport layer, a standalone solar water splitting tandem cell was built, delivering a solar-to-hydrogen efficiency of 4.55%..

Hosted by Dr Mónica Lira Cantu Nanostructured Materials for Photovoltaic Energy Group, ICN2