Published online by Cambridge University Press: 15 March 2011
We report on recent progress in fabricating an inorganic solid state solar cell based on a nano-structured substrate with an extremely thin absorber, the so-called eta-cell. The cell uses HgCdTe as an absorber layer and TiO2 as a substrate. By adjusting the Hg/Cd ratio the conduction band edges in these two materials can be brought into alignment. This tuning provides an ideal tool to optimize the optical and electrical properties of the cell. In qualitative agreement with earlier work we find a band offset of 0.25 eV to give maximum transfer rates across the interface. The optimized cell has a short circuit current of 15 mA/cm2 and an open-circuit voltage of 0.6 V. We discuss the optical and electrical properties of the cell, and outline ideas to further improve the performance.