Two types of photovoltaic materials are investigated: perovskites and CIGS (Cu-In-Ga-Se). In this lab the material properties are improved and the interfaces and the different layers in the thin film solar cell structure are studied and optimised. The size of solar cells can range from a few mm size (for the basic research) up to 35 cm x 35 cm thin film modules (to test applications). The thin film PV research is also embedded in the collaboration consortium Solliance*.
Lieve De Doncker
There are two main R&D topics on CIGS studied:
- Passivation of CIGS absorber layers to achieve a thinner and simplified CIGS absorber material. The cost and reliability of CIGS solar cells can be improved substantially with this approach as has been shown already for silicon solar cells. The end goal is to realise high efficient CIGS solar cells with low cost and long reliability.
- New absorber materials are developed for future applications. For tandem cells, a high band gap version (above 1.6 eV) of CIGS with pure sulphur (Cu-In-Ga-S) or CGS (Cu-Ga-Se) is under development to be used as the cell on top of silicon bottom cell. Also, CIS (Cu-In-Se) is investigated as a potential for a bottom cell, when using e.g. a high band gap perovskite as the top cell. The CIS an also be used for applications whereby IR absorption is important. Besides CIGS compounds, also other sulphide and selenide compounds are possible to realise and study.
The lab has the capabilities to selenise and sulfurise precursor layers with elemental Se and S, as well as with H2Se and H2S gas. It allows to exploit the full potential of chemical reactions to create any sulphide or selenide compound and do in-depth investigations of the phase creation. The lab is equipped to finalise a complete solar cell device. All physical and optical-electrical analysis equipment for fast and advanced characterisation is present.
Over a relatively short development period, the initial efficiency of perovskite solar cells (PSCs) has rocketed from 3.8% in 2009 up to a certified record efficiency of 22.7% in 2017. So far these efficient PSCs are of small-scale (typically ≤1cm2). Despite this impressive initial performance, critical issues remain which hamper the industrial application of this material. Besides the instability, upscaling is another bottleneck for this PV technology. This upscaling is one of the key activities in the perovskite PV developments here.
The new assembly line allows to process full modules up to 35x35cm². A slot die coater can deposit solution-based materials while a vacuum thermal evaporation and sputtering system makes a combination of oxide and metallic coatings accessible for both passivation and electrode layers. Co-deposition of up to 4 materials is available, even to create quaternary photo-active layers like CIGS. In addition, a versatile 3-wavelength picosecond laser system is available for the creation of very narrow interconnections between adjacent cells in the modules. Dispenser and curing stations are available to complete the module packaging. All of these tools are integrated in or connected to controlled atmosphere gloveboxes.
The line allows versatility of carrier materials to be used, ranging from glass, plastic to metal sheets. This enables to create opaque or semi-transparent modules, either rigid or flexible. Variable interconnection schemes can be developed with the laser system to fabricate customised modules.
- CIGS solar modules
- Tandem solar cells
- Solar cells with sulphide or selenide absorber layers
- Customised solar modules
- opaque or semi-transparent modules, either rigid or flexible
- Tandem solar cells
- IoT up to BIPV
Deposition and processing tools available (from 5cm x 5cm up to 35cm x 35cm)
- Atmospheric anneal furnaces
- Vacuum selenisation furnace with H2Se and H2S
- S and Se elemental reactor furnace
- CdS chemical bath deposition
- Spin, blade and slot die coating
- Vacuum thermal co-evaporation
- Linear sputtering
- Mechanical scribing
- 3-wavelength picosecond laser patterning
- UV-curing press, robot and dispenser
- Class A IV set-up
- Indoor IV set-up
- Atmosphere, temperature and light controlled climatic chambers
- Carrier recombination life time meter (< 100ps)
- 4-point probe
- Laser scanning microscope