In our clean room lab we develop high efficiency thin film solar cells based on the chalcogenide materials Cu(In,Ga)Se2 (abbreviated as CIGS) and Cu2ZnSn(S,Se)4 (abbreviated as CZTS). Both these materials have extraordinary absorption properties and can therefore be made very thin. Less than 1 micrometer is enough to absorb all available sunlight! Our long term goal is to explore and challenge the theoretical limit for efficiency of around 30 % and we are at present at about 20 % solar to electric power conversion efficiency. In related research we also study the use of advanced optical designs – which involve nanoparticle plasmon resonances – to push the thicknesses of solar cell absorber layers much further, even down to a few nanometers.
Synthesizing solar cells are one part of our research, but measurements and understanding how they work and can be improved is just as important. For both, working in a structured way and extensive equipment is needed. We have a large activity working freely over the borders of material science, electronic engineering, chemical engineering, modeling and theory. Below you can follow the links to read more about our different research groups.
CIGS-based thin film solar cells
CIGS is an acronym for Cu(In,Ga)Se2. This semiconductor material is an excellent light absorber and has reached efficiencies of over 20 %. Our research aims to develop CIGS-solar cells with as high efficiency as possible.
CZTS — solar cells from abundant elements
Sometimes solar cells contain rare or expensive elements, for example indium and tellurium. CZTS is an abbreviation of Cu2ZnSn(S,Se)4, a material composed of only abundant and non-toxic elements, which therefore has the advantage of a lower cost and reliable access to material. The purpose with the research is to achieve as high performance as for example solar cells of CIGS and CdTe.
Materials chemistry of CZTS and CIGS absorbers
The many and varied chemical reactions taking place during formation of CZTS or CIGS absorber layers together impart some of the key properties that determine solar cell performance. We investigate reactions occurring in the films and at their surfaces and interfaces during high temperature formation, from both experimental and theoretical standpoints, to develop improved materials and synthetic strategies.
New window layer structures for CIGS/CZTS solar cells
We develop the window layer structure for thin film solar cells based on chalcogenide absorbers like CIGS and CZTS. The effect of changing optical, electrical and structural material properties of the window layer is related to the electrical performance of the solar cell devices.
Plasmon based Ultrathin Photovoltaics
We explore possibilities for effective harvesting of sunlight in layers of only 10 nanometer characteristic thickness. By dramatically reducing the absorber layer thickness to this level, cost and resource savings are enabled along with the possibility for enhanced conversion efficiency of light to electricity. The research thus strives to contribute to the creation of a new class of efficient photovoltaic solar cells based on absorber layers operating near the lower thickness limit, as determined by the governing physics.