The Optical Properties Of Zn-N Co-doped TiO₂ Thin Films By Sol-Gel Spin-coating Method

Titanium Dioxide?abbreviated as TiO₂?,which consists of anatase phase,rutile phase and plate-titanium phase,has been widely used in sunscreen emulsions,pigments,capacitors and solar cells due to its cheap,non-toxic,stable physical and chemical properties.However,TiO₂ is a broad-band semiconductor that can only absorb a small portion of the solar spectrum and is not active in visible light,which greatly limits its application in solar energy and other fields,so reducing the optical band gap of TiO₂ has become a hot issue of particular concern to researchers.In this paper,we selected intrinsically characterized TiO₂ films,Zn single-doped TiO₂ films and Zn-N co-doped TiO₂ films on glass and silicon substrates by sol-gel spin coating method,respectively,to explore the influence of different calcination temperature and doping amount on the structure and optical properties TiO₂ the films.The optimum parameters for TiO₂ films were determined by review of literature and experimental inquiry:pH 2-3,sol-gel concentration of 0.5mol/L,spin coating number of 3 layers,pre-annealing temperature of 70?,and large annealing temperature of 600?.In this paper,the effect of Zn doping on TiO₂ films was investigated.The doping of Zn resulted in enhanced diffraction peak strength of TiO₂?101?,reduced grain size,flatter and denser surface,red shifted absorption edge and reduced optical band gap value.When the Zn doping is 2.Oat%,the film has relatively better structural properties,a denser and smoother surface,more homogeneous grain,and a greater red shift and light response range on the absorbing side,with a corresponding smaller optical band gap value of 3.419 eV.In this paper,the effect of different N doping amounts on Zn-N co-doped TiO₂ films was investigated.It was found that the intensity of the?101?crystalline diffraction peaks of the remaining samples after co-doping was reduced and the crystalline spacing generally increased,except for the doping amount of 8.Oat%.However,a more pronounced red shift of the absorbing edge overall occurred in all samples,and the width of forbidden band was significantly reduced.When the N doping is 8.Oat%,the sample has the strongest?101?peak intensity the sharpest peak type,the best meritocratic orientation,the greatest red shift of the absorption spectrum,the lowest optical band gap value of 3.356 eV,and the highest utilization rate for visible light.