Energy Materials

At the Laboratory for Energy Materials (LEM)  we are interested in making and testing complex materials necessary for energy conversion and storage using low cost and innovative methods.

Currently our research is focused on the preparation and characterization of p-type semiconductor absorber layers for use in thin film solar cells. Its main scientific goal is to understand how to convert a simple precursor layer into single phase high quality semiconductor material.

  • Precursor layers are synthesized with two techniques (I) electrodeposition and (II) spin coating nano particles.
  • High temperature electrodeposition allows the direct deposition of p-type semiconductors.
  • Precursor layers are converted into semiconductor thin films by the application of energy using either heat or light irradiation. The Laboratory for Energy Materials studies whether annealing is possible within 1 second.
  • A quality assessment of semiconductors using photo-electrochemistry allows the discriminiation of suitable layers for devices.
  • LEM researchers try to understand the growth processes in terms of structural, thermodynamic and kinetic parameters. 

The Laboratory for Energy Materials is headed by Dr Phillip Dale.


  • February 2018 : Article published in Nature Communications

Sodium enhances indium-gallium interdiffusion in copper indium gallium diselenide photovoltaic absorbers

Photovoltaic solar panels convert sunlight into electricity. For this to happen, sunlight must be absorbed by an active component called the absorber. In absorber materials, the incident light is able to excite electrons. One type of absorbers is made of many small grains packed into a thin layer (typically one hundred times thinner than a hair). The grains contain several chemical elements (such as copper, indium gallium and selenium). In the type of absorber investigated here, the depth distribution of these elements is designed to direct the flow of electrons excited by the sunlight, so that the maximum electricity power can be generated.

In simple terms, this work shows that if the absorber is made of only one grain, adding a small amount of sodium helps to homogenize the distribution of the elements. This is very surprising, because more than 20 years of previous research have consistently shown the opposite effect on absorbers made of many grains. Thanks to these results, we can now conclude that sodium has a dual effect: it homogenizes the elements inside each grain but it slows down homogenization from grain to grain.

You can freely download the article here

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