Our research program focuses on innovative device concepts for, amongst others, energy harvesting, data storage and actuation, as well as in the fundamental electronic processes underlying these functions. Together with collaboration partners we develop, investigate and model the novel molecular materials and device architectures that are needed to bring these device concepts to live. Specific research topics include organic solar cells, molecular ferro- and piezoelectrics, organic thermoelectrics and ratchets.
Organic Solar Cells
For organic solar cells, our interest focuses on non-equilibrium phenomena that distinguish these devices from their inorganic counterparts. In contrast to essentially all other (inorganic) photovoltaic systems, the thermalization of photocreated charges in organic semiconductors is a slow process. Much of our work focuses on unraveling how this affects device performance.
Ferro- and Piezoelectrics
Apart from being physically rich systems, ferroelectric materials are relevant for a wide variety of applications like data storage (e.g. FeRAM), actuation, transduction and actuation, and energy harvesting. The unique feature of organic ferroelectrics is the possibility to change, improve and add functionality through modification of the molecular structure. As an example, we were the first to demonstrate that ferroelectric polarization can couple to the bulk charge carrier mobility, giving rise to a fundamentally new resistive switching effect.
On paper, ‘heat’ is an extremely abundant source of energy, being available as waste product and as part of the solar spectrum. Unfortunately, converting heat to useful electrical power is far from trivial. We pursue doped hybrid and organic materials for use as low-cost, eco-friendly active layers in printable thermoelectric generators. Through experiments and modeling we try to exploit the inherently low thermal conductivity of organic (semi)conductors while boosting the electrical conductivity and thermopower.
The ratchet as a ‘scientific device’ was conceived about a century ago as a thought experiment to test the 2nd law of thermodynamics. While ratchets are most easily visualized as marbles on a washboard, we investigate electronic ratchets defined by lithographic or molecular patterns. Specifically, we aim to ultimately use ratchets to convert (long wavelength) light and heat into electrical power; being inherently nonequilibrium devices, ratchet performance is not fundamentally limited by equilibrium thermodynamics.