Engin Özkol

Fabrication of Ag Nanoparticles Embedded in Al:ZnO as Potential Light-Trapping Plasmonic Interface for Thin Film Solar Cells

Incident photon conversion efficiency of the absorbing materials at either side of a thin film solar module can be enhanced by integrating a plasmonic interface. Silver nanoparticles represent a good candidate that can be integrated to a thin film solar cell for efficient light-trapping. The aim of this work is to fabricate plasmonically active interface consisting of Ag nanoparticles embedded in Al:ZnO that has the potential to be used at the front surface and at the back reflector of a thin film solar cell to enhance light-trapping and increase the photoconversion efficiency. We show that Ag can readily dewet the Al:ZnO surface when annealed at temperatures significantly lower than the melting temperature of Ag, which is beneficial for lowering the thermal budget and cost in solar cell fabrication. We find that such an interface fabricated by a simple dewetting technique leads to plasmonic resonance in the visible and near infrared regions of the solar spectrum, which is important in enhancing the conversion efficiency of thin film solar cells.

High haze nature of textured Al:ZnO with Ag nanoparticles for light management in thin film solar cells

We report on fabrication of plasmonic interfaces consisting of Ag nanoparticles on flat and textured Al:ZnO for use at the front surface of thin film solar cells to enhance light trapping and photo-conversion efficiencies. We show that outstandingly high transmittance haze is achieved from single step HCl surface textured Al:ZnO and demonstrate Ag dewetting on textured and flat Al:ZnO surfaces upon annealing at moderate temperatures. Optical response of these plasmonic interfaces clearly display plasmonic resonances in the visible and near infrared, which is crucial for enhancement of photovoltaic conversion efficiency in thin film solar cells.

Structural properties of a-Si films and their effect on aluminum induced crystallization

In this paper, we report the influence of the structural properties of amorphous silicon (a-Si) on its subsequent crystallization behavior via the aluminum induced crystallization (AIC) method. Two distinct a-Si deposition techniques, electron beam evaporation and plasma enhanced chemical vapor deposition (PECVD), are compared for their effect on the overall AIC kinetics as well as the properties of the final poly-crystalline (poly-Si) silicon film. Raman and FTIR spectroscopy results indicate that the PECVD grown a-Si films has higher intermediate-range order, which is enhanced for increased hydrogen dilution during deposition. With increasing intermediate-range order of the a-Si, the rate of AIC is diminished, leading larger poly-Si grain size.