A Cu${}_x$S/GO composite hole transport layer for photovoltaic performance enhancement on CuInS${}_2$ quantum dot-sensitized solar cells

In this work, a Cu${}_x$S/GO composite hole transport layer is prepared on the surface of TiO${}_2$/CuInS${}_2$ photo-electrodes to modulate the charge transfer efficiency of quantum dot-sensitized solar cells. The normalized PL intensity of TiO${}_2$/CuInS${}_2$ photo-electrodes had been obviously quenched with the as-prepared Cu${}_x$S/GO composite hole transport layer, which had exhibited excellent charge separation properties of the solar cells. Due to the reduce of charge recombination traps under Cu${}_x$S/GO composite hole transport layer, the charge transfer efficiency of the solar cells had been effectively improved. As a result, the higher V${}_{oc}$, FF and J${}_{sc}$ value can be obtained for TiO${}_2$/CuInS${}_2$ quantum dot sensitized solar cells with this Cu${}_x$S/GO composite hole transport layer, which had exhibited the photovoltaic conversion efficiency enhancement from 4.85% to 6.07%.