Topics

Polycrystalline silicon thin-film solar cells on glass

Liquid-phase crystallized silicon on glass (LPCSG) prepared by either electron-beam crystallization (EBC) or laser crystallization (LC) resembles wafer-based multicrystalline Si. This material features the potential to combine the advantages of both thin-film technologies (low cost) and wafer-based Si photovoltaics (high efficiencies) and consequently to overcome the limitations of the established Si thin-film technologies.

Overview Silicon based heterostructures

Solar cells based on mono-, poly-, or thin film silicon where the highly doped layers at the front and the back sides are deposited from the gas phase at low temperatures. The hetero contact is formed by the Si-absorber and a material with higher energy band gap (TCO, a-Si:H, SiC). The work aims in particular at the development of an "interface engineered" transition region between the Si-absorber and the heteroemitter.

Hybrid structures from inorganic and organic materials

Combining two materials often creates a multitude of unexpected properties and functionalities. In the framework of hybrid structure research we follow this approach and join organic and inorganic materials (e.g. semiconductors). High cross-sections for light absorption and large electric dipoles are key features of organic molecules which can be varied over a wide range. On the other hand, inorganic semiconductors benefit from a crystalline structure and typically show enhanced charge transport. Combining the advantages of both, inorganic and organic materials, while compensating their drawbacks is the central challenge of hybrid structure research.

Electron paramagnetic resonance (EPR)

Electron paramagnetic resonance (EPR) is a spectroscopic tool for the study of materials containing unpaired electron spins (e.g. organic radicals, free charge carriers, semiconductor defect states or transition metal ions). In our lab EPR is employed to study structure-function relationships of paramagnetic states in materials relevant for energy production and conversion, in particular photovoltaic (PV) devices. For this purpose dedicated multi-frequency and multi-resonance EPR instrumentation from GHz to THz frequencies is available in our lab. For in operando studies of spin-dependent charge transport processes in fully processed devices we design and employ novel indirect (optical and/or electrical) detection schemes.