Micro-sized thin-film solar cells via area-selective electrochemical deposition for concentrator photovoltaics application.

Micro-concentrator solar cells enable higher power conversion efficiencies and material savings when compared to large-area non-concentrated solar cells. In this study, we use materials-efficient area-selective electrodeposition of the metallic elements, coupled with selenium reactive annealing, to form Cu(In,Ga)Se semiconductor absorber layers in patterned microelectrode arrays. This process achieves significant material savings of the low-abundance elements.

Chemical instability at chalcogenide surfaces impacts chalcopyrite devices well beyond the surface.

The electrical and optoelectronic properties of materials are determined by the chemical potentials of their constituents. The relative density of point defects is thus controlled, allowing to craft microstructure, trap densities and doping levels. Here, we show that the chemical potentials of chalcogenide materials near the edge of their existence region are not only determined during growth but also at room temperature by post-processing.

The hunt for the third acceptor in CuInSe and Cu(In,Ga)Se absorber layers.

The model for intrinsic defects in Cu(In,Ga)Se semiconductor layers is still under debate for the full range between CuInSe and CuGaSe. It is commonly agreed by theory and experiment, that there are at least one shallow donor and two shallow acceptors. Spatially resolved photoluminescence on CuGaSe previously revealed a third acceptor.

Time-resolved photoluminescence on double graded Cu(In,Ga)Se - Impact of front surface recombination and its temperature dependence.

Time-resolved photoluminescence (TRPL) is applied to determine an effective lifetime of minority charge carriers in semiconductors. Such effective lifetimes include recombination channels in the bulk as well as at the surfaces and interfaces of the device. In the case of Cu(In,Ga)Se absorbers used for solar cell applications, trapping of minority carriers has also been reported to impact the effective minority carrier lifetime.