Low-temperature preparation of high electrical conductivity amorphous compact Zn-doped TiO2 thin films via vacuum ultraviolet for high efficient solar cells

Vacuum ultraviolet (VUV) with a wavelength of 172 nm was employed to prepare amorphous Zn-doped TiO₂ (ZTO) thin films using titanium tetraisopropoxide as a precursor to form TiO₂ and zinc(II) dibutyldithiocarbamate as a Zn doping source. During the VUV irradiation on the precursor films, the incorporation of zinc and the departure of nitrogen and sulfur enhance the conductivity and electron mobility of the thin films. The prepared ZTO thin films were used as the electron transport layer to fabricate mesoporous perovskite solar cells (PSCs). The optimal doping molar ratio of zinc was determined to be 2 % according to the photoelectric performance of PSCs based on the ZTO thin films. The improved interfacial contact between the ZTO electron transport layer and the electrode substrate reduces the interfacial charge transfer resistance. The synergistic effect of ZTO electron transport layer enhances the power conversion efficiency (PCE) of PSCs from 18.28 % to 21.21 %. In addition, the ZTO thin film was used as the compact layer in quantum dot-sensitized solar cells, significantly improving their performance. Therefore, the VUV irradiation technique is a general method to prepare the doping metal oxide thin films for fabricating high efficiency solar cells with the compact thin film structure.