Gold nanoparticle-PVP based coating for efficiency enhancement of solar cells

In this work we report on the optimization of a simple-spin coating technique using solution based Au colloidal nanoparticles and polyvinylpyrrolidone (PVP) and evaluate the potential for improving the efficiency of thin-base (<1 micron) conventional p/n GaAs and InP/InAsP multi quantum well (MQW) p-i-n solar cells. Optical properties of the coatings are analyzed by reflectance spectroscopy and spectroscopic ellipsometry. It is experimentally demonstrated that the approach yields to a remarkable improvement of the performance of studied devices. Quantum efficiency and reflectance analysis show an increase of the near-band edge and below bandgap (MQW) conversion efficiencies as well as a decrease of overall reflection losses. The proposed process is shown to be reversible (possibility of non-intrusive solvent based coating removal) and capable of improving device current outputs and fill factors. Significant AM0 efficiency increases for the conventional GaAs p/n and InP p-MQW-n devices are recorded both for samples coated with AuNP-PVP and PVP. However analysis indicate that the main improvement in IV characteristics is to be associated with a PVP related antireflect-coating effect.