Defect states in hybrid solar cells consisting of Sb_2S_3 quantum dots and TiO_2 nanoparticles

摘要

We have studied defect states in an organic-inorganic hybrid solar cell containing Sb_2S_3 quantum dots (QDs) and TiO_2 nanoparticles (NPs) by using deep level transient spectroscopy (DLTS). An Au electrode was deposited as a Schottky contact on the sample, where the Sb_2S_3 QDs were distributed on the surface of TiO_2 NPs by chemical synthesis. The activation energy and capture-cross section of an interface state between the Sb_2S_3 QDs and the TiO_2 NPs were found to be about 0.78 eV and 2.21 x 10~(-9)cm~(-2), respectively. Also, the densities of this interface trap under a measurement voltage of -IV were approximately 2.5 × 10~(17)cm~(-3). Based on these results, the interface trap was positioned around E_c - 1.03 eV below the conduction band edge of Sb_2S_3 QD. Thus, the external quantum efficiency of the solar cell was affected because of its role as a recombination center for carriers generated from Sb_2S_3 QDs.