Employment of CuI on Sb₂S₃ Extremely Thin Absorber Solar Cell: N719 Molecules as a Dual Role of a Recombination Blocking Agent and an Efficient Hole Shuttle

摘要

FTO/TiO2/Sb2S3/CuI/Pt-FTO solar cell which utilizes Sb2S3 as an extremely thin light absorbing layerand CuI as a hole conducting material is an example for novel extremely thin solar cells. The solar cellshows very poor performance of lower open-circuit voltage of 0.256 V, a short-circuit current density-2 of 9.50 mA cm and a fill factor of 0.387 under 1 sun illumination for a cell with active surface area of-2 0.25 cm . This is due to the recombination of photo-generated electrons with the holes of the highlyconducting CuI. This recombination can be overcome to a certain degree by applying a blocking layeron the Sb2S3 layer to cover the voids in the Sb2S3 layer. The application of N719 dye on the Sb2S3layer as a recombination blocking layer enhances the conversion efficiency of the solar cell by a factorof 2.5 due to the enhancement of all the solar cell parameters to result in an open ircuit voltage of-2 0.37, short-circuit1 current density of 13.4 mA cm , and a fill factor of 0.503. IPCE, dark current andtransmittance spectra measurements reveal that the main role of the dye on the Sb2S3 layer is thesuppression of recombination the electrons with the holes in CuI. Interactions of the NSC groups in theN719 dye with CuI are facilitating the transfer of the photo-generated holes in Sb2S3 to the CuI layerfor efficient transport towards the counter electrode.