Enhanced electrodynamic characteristic and tunable band gap formed by the multilayer TixZn oxide film promising as a photoanode for solar cells

As a clean and efficient energy material, the efficiency of solar battery can be greatly promoted by matching suitable photoanode. Among them, TiO2 and ZnO are natural materials with appropriate energy level and excellent carrier concentration, which have enormous application potential. Herein, a multilayer Ti10Zn oxide film with similar band gap of TiO2 (ECB=-0.70 V vs. NHE) and a parallel electrical property of ZnO has been obtained by atomic layer deposition (ALD). The formation mechanism has been analyzed by comparing multilayer TixZn oxide films with different proportions and pure TiO2 (ZnO) film. Firstly, scanning electron microscope (SEM) indicating homogeneous morphology of these films. Then X-ray photoelectron spectroscopy (XPS) along with the X-ray diffraction (XRD) measurements and the thicknesses fitted by ellipsometric spectra reveal that when x > 10, the ZnO substance mainly exist in the form of interstitial atoms and conversely occupies a separate layer of spatial structure when x < 10. While the film shows maximum Zn 2p(3/2) binding energy and preferential growth orientation of spacing in (002) direction with ZnO-like crystal structure when x = 10 (Ti10Zn). The resistivity and Hall measurement confirm Ti10Zn with an excellent electrodynamic property with a parallel Hall mobility of 9.34 cm(2) and carrier density of 1.86 x 10(20) cm(-3) even higher than that of pure ZnO. Transmission spectra along with photo-luminescence measurement demonstrated similar band gap values of TixZn oxide films with TiO2 and high spectral transmittance (solar light utilization rate>70%). This work highlights TiO2/ZnO composite films with great application prospects as solar cell photoanode materials and other optoelectronic application fields.

Automated summary

A multilayer Ti10Zn oxide film with similar properties of TiO2 and ZnO has been obtained by atomic layer deposition, which shows excellent electrodynamic and optical properties with great application potential.