Charge trapping

Through a combination of experimental methods and theoretical predictive modelling CEEM researchers are providing atomic level insights into how these traps reduce the flow of energy in thin film materials used in the sustainable energy industry.

A titanium dioxide based material, commonly used in the manufacture of solar panels, was electrochemically doped with hydrogen to see how this would impact both on the number and the depth of the traps in the nanomaterial.

Our modelling predicted that the doping would change the transport characteristics of the material with the hydrogen filling the gaps where the charge could become trapped. Indeed, CEEM’s research revealed that this doping effect produced a 50% reduction in the number of traps within the material.

More significant, perhaps, we also found that there was a seven-fold improvement in the photocurrent enhancement factor.

This more than compensates for the negative impact the hydrogen had through the creation of deeper traps.

We are now working with two leading private sector partners, Dyesol and Cristal, on an £800,000 EPSRC funded project that will investigate ways to eliminate these traps by chemically modifying the surfaces of nanoparticles prior to sintering into a film.

CEEM will combine the predictive power of first principles theoretical modelling with structural, spectroscopic and photophysical materials characterisation to quantify the factors responsible for charge trapping at surface and interfaces at an atomistic level.

Once validated and refined on unmodified films, we will use predictive modelling to assess modification strategies to reduce charge trapping. This ability to theoretically screen various possible modification routes is a key advantage to the CEEM approach.