Light induced electrical metastability in photovoltaic materials and devices
Tidsperiod: 2012-01-01 till 2015-12-31
Projektledare: Charlotte Platzer Björkman
Budget: 3 200 000 SEK
The aim of my project is to study light-induced metastable effects in semiconductor materials used in thin film solar cells. These materials are far from perfect single crystals where solid theoretical understanding exists. Still, device efficiency of 20% has been shown which is comparable to that of multicrystalline silicon solar cells. Development of device models for thin film solar cells by verification using in-house experimental data is an important part of this project.Controlled variation of material parameters can be made in several cases as for example band gap of Cu(In,Ga)Se2 p-type layer and ZnO-based n-type layer through alloying. Opto-electrical characterisation includes current voltage, spectral response, resistivity and Hall measurements. The evolution of electrical properties under wavelength dependant illumination will be used for both devices and single materials. By comparative studies of device structures with different material combinations, the origin of light induced effects will be traced. This will be supported by device modelling using input from electrical characterization of individual layers as well as interface characterization and compared to theory. The project will add to the general understanding of defects and opto-electrical properties of polycrystalline semiconductor devices.