Indium Gallium Oxide Emitters for High-Efficiency CdTe-Based Solar Cells

There are limited choices for front-surface, electron-selective contacts (emitters) for CdTe solar cells, thus hindering scientific and technical development. Here we investigate the photovoltaic performance of devices fabricated with (InxGa1-x)(2)O-3 (IGO) emitters with varying In-to-Ga ratios prepared by cosputtering. In agreement with predictions, an IGO emitter with a 4.03 eV bandgap (x = 0.36) allowed fabrication of devices with efficiencies of 16%. Increasing the performance to higher values will be enabled by increasing the transmission through the IGO-coated substrate and decreasing the bulk and back interface recombination. These findings demonstrate IGO materials as effective emitters in high-efficiency CdTe-based solar cells.