The Preparation Of Nano-gold-doped Titanium Dioxide And Its Surface Enhancement Effect

Titanium dioxide(TiO2)served as the electron transport layer of perovskite solar cells(PSC)has attracted much research interest recently.To improve the electron transport efficiency of TiO2 layer,the structural modification has been successfully utilized as an effective approach.For example,the incorporation of metal nanoparticles into TiO2layers was utilized to largely suppress the fast recombination of electron-hole pairs.One excellent candidate is Au nanoparticles(AuNPs),holding the strong and tunable Localized Surface Plasmon Resonance(LSPR)in the visible and near-infrared spectral regions and showing the improved capability of andgap engineering when incorporated into the TiO2 matrix.[8-10]However,when non-uniformly dispersed in the mesoporous TiO2(w-TiO2)layer,AuNPs may produce short circuit by forming a conducting channel.A planar structure of fluorine-doped tin oxide(FTO)/TiO2 dense layer(d-TiO2)/AuNPs doped TiO2(Au@TiO2)/a-TiO2/CH3 NH3PbI3/spiro/Au photovoltaic device is assembled and measured.Apart from the typical reduction method to prepare AuNPs(cited by r-Au below),the gold chloride solution was added into TiO2 solution directly without the chemical reduction.The photolysis of HAuC1U to Au atoms was completed by daylight irradiation and the nucleation and growth of AuNPs took place randomly within the TiO2 skeleton to avoid the formation of the conducting path which is induced by the aggregation of AuNPs.Moreover,a-TiO2layer was introduced on top of Au@TiO2 layer intentionally to further cut off the leaking channels if have any.The deposition of AuNPs on TiO2 was confirmed by the scanning electron microscopy and X-ray diffraction characterization.The results have shown the AuNPs are identified by the higher contrast and holding regular geometric shapes.The XRD characterization confinns the deposition of Au onto the TiO2 matrix.The UV-vis spectroscopy shown that the incorporation of AuNPs has enhanced the absorption of visible light by generating more localized surface plasmon resonance charge pairs.Electrochemical impedance spectroscopy(EIS)characterized the internal resistance and charge transfer kinetics of the AuNPs-TiO2 based perovskite solar cells,and the interlayer electron transport capability is maximized under the in-situ method in this paper.The result show that Au@Ti02 film with in-situ method showed better performance.The resulting composites with Au nanoparticles holding the Surface Plasmon Resonance scattering can work as the efficient electron transport layer in the perovskite solar cells.With the combination of amorphous TiO2 capping layer,the optimized device shows the enhanced higher short-circuit current density(24.16 mA cm-2)and open circuit voltage(1.07 V),achieving the 16.8%efficiency.