// Improving functional and interfacial layers to engineer highly efficient CIGS solar cells in the EFFCIS-II project
Researchers are investigating some fundamental questions in physics and chemistry in a joint project called EFFCIS-II, with the aim to make thin-film solar modules featuring Cu(In,Ga)Se2 technology, or CIGS for short, an even more attractive economic proposition. Funded by the German Federal Ministry for Economic Affairs and Energy (BMWi), this research group has experts from science institutes, universities and industry collaborating under the auspices of ZSW to boost CIGS cells’ efficiency by means of novel passivation layers and a modified absorber material.
The researchers involved in EFFCIS-II are building on the results of the first EFFCIS project to pursue new avenues of approach to optimizing CIGS volume properties, increasing CIGS band-gap energy by adding chemical elements, reducing the CIGS layer thickness, and achieving bilateral interface passivation on the front and back of CIGS cells. They expect this combination of new approaches and evolutionary optimizations to boost modules’ efficiency while cutting costs.
Analytical tools with high temporal and spatial resolutions such as tomographic atom probes, cathodoluminescence detectors, X-ray emission spectrometers and transmission electron microscopes serve to characterize absorber layers and associated interfaces. Researchers are also applying innovative methods such as in-situ X-ray diffraction and X-ray fluorescence to monitor the growth of the CIGS layers in real time. And they are using state-of-the-art 3D component simulation techniques and ab-initio modeling to explore the effect of the material parameters for individual components such as absorber, buffer and passivation layers on the performance of the CIGS solar cell.
ZSW is contributing to the EFFCIS-II project by developing indium-based buffer layers deposited by way of sputtering or wet chemical methods, and CIGS cells in which additional gallium increases the band gap.
