Bulk and surface recombination properties in thin film semiconductors with different surface treatments from time-resolved photoluminescence measurements.

The knowledge of minority carrier lifetime of a semiconductor is important for the assessment of its quality and design of electronic devices. Time-resolved photoluminescence (TRPL) measurements offer the possibility to extract effective lifetimes in the nanosecond range. However, it is difficult to discriminate between surface and bulk recombination and consequently the bulk properties of the semiconductor cannot be estimated reliably.

Refractive indices of layers and optical simulations of Cu(In,Ga)Se solar cells.

Cu(In,Ga)Se based solar cells have reached efficiencies close to 23%. Further knowledge-driven improvements require accurate determination of the material properties. Here, we present refractive indices for all layers in Cu(In,Ga)Se solar cells with high efficiency.

Single-graded CIGS with narrow bandgap for tandem solar cells.

Multi-junction solar cells show the highest photovoltaic energy conversion efficiencies, but the current technologies based on wafers and epitaxial growth of multiple layers are very costly. Therefore, there is a high interest in realizing multi-junction tandem devices based on cost-effective thin film technologies. While the efficiency of such devices has been limited so far because of the rather low efficiency of semitransparent wide bandgap top cells, the recent rise of wide bandgap perovskite solar cells has inspired the development of new thin film tandem solar devices.

Voltage dependent admittance spectroscopy for the detection of near interface defect states for thin film solar cells.

Recently recorded efficiencies of Cu(In,Ga)Se based solar cells were mainly achieved by surface treatment of the absorber that modifies the buffer-absorber interface region. However, only little is known about the electronic properties within this region. In this manuscript voltage dependent admittance spectroscopy is applied to low temperature grown Cu(In,Ga)Se based solar cells to detect near interface defect states in the absorber.

Energy Harvesting by Subcutaneous Solar Cells: A Long-Term Study on Achievable Energy Output.

Active electronic implants are powered by primary batteries, which induces the necessity of implant replacement after battery depletion. This causes repeated interventions in a patients' life, which bears the risk of complications and is costly. By using energy harvesting devices to power the implant, device replacements may be avoided and the device size may be reduced dramatically.