Researchers at the University of Kentucky, US, have developed two novel device configurations for thin-film CdS-CdTe solar cells, where the traditional CdS window layer is replaced by nanowires of CdS embedded in an aluminum oxide matrix or free standing, as shown in the figure above.

A 26.8% improvement in power-conversion efficiency over the traditional device structure is expected to result from (i) enhanced spectral transmission of sunlight through the window layer and (ii) a reduction in the junction area/optical area ratio, which reduces the total number of interface states at the heterojunction, thus yielding higher Voc.

In initial experiments, the team fabricated nanostructured devices based on the two designs and obtained Voc, Jsc, FF and efficiency values of 705 mV, 25.3 mA/cm2, 36.4% and 6.5%. Process optimizations for higher performance are in progress.

Full details can be found in the journal Nanotechnology.