Preparation And Properties Research Of Al/La Co-doped ZnO Transparent Conductive Film

Transparent conductive film has been widely applied in solar cells and liquid crystal display etc. field. Currently, ITO film, which raw material cost and equipment cost are very high, have occupied a large proportion of the market, so, the low-cost ZnO-TCO film has attracted much interest recently. In this thesis, Sol-Gel process was used to prepare Al/La co-doped ZnO transparent conductive film on Na2O-CaO-SiO2 glasses substrate. The influence of Sol concentration, Al3+/La3+ doping concentration, Sol aging days, coating layers and thermal treatment temperature on film's conductive performance were investigated, the conclusions are as follow:(1) The Sols were synthesized via Sol-Gel process, zinc acetate dihydrate (C4H6O4Zn·2H2O) was used as the precursor, ethanol was used as the solvent, monoethanolamine (C2H7NO) was used as the stabilizer, aluminium chloride hexahydrate (AICl3·6H2O) was used as doping to mixed a complex sol, transparent conductive films were prepared on Na2O-CaO-SiO2 glasses substrate by dip-draw process. When n(Zn2+)=1.1mol/L, n(Al3+)=0.8mol/L, sols sealed aging l day, coated 8 layers with 6cm/min speed, thermal treat 5mins on 400℃after each draw and final 60mins on 500℃. The optimum sheet resistance of the ZnO:Al transparent conductive film was 2.39KΩ/□.(2) Other conditions are same as conclusion (1), change doping from aluminium chloride hexahydrate to Lanthanum(III) nitrate hydrate, and adjust n(La3+)=0.05mol/L. The optimum sheet resistance of the ZnO:La transparent conductive film was 2.87KΩ/□.(3) Zinc acetate dihydrate (C4H6O4Zn·2H2O) was used as the precursor, ethanol was used as the solvent, monoethanolamine (C2H7NO) was used as the stabilizer, aluminium chloride hexahydrate (AICl3·6H2O) and Lanthanum(Ⅲ) nitrate hydrate were used as doping to mixed a complex sol(Lanthanum(Ⅲ) nitrate hydrate was added into the sols earlier than aluminium chloride hexahydrate), transparent conductive films were prepared on Na2O-CaO-SiO2 glasses substrate by dip-draw process. When n(Zn2+)=1.1mol/L, n(Al3+)=0.8mol/L, n(La3+)=0.05mol/L, sols sealed aging 1 day, coated 8 layers with 6cm/min speed, thermal treat 5mins on 400℃after each draw and final 60mins on 500℃. The optimum sheet resistance of the ZnO:(La/Al) transparent conductive film was 320Ω/□.The transmittance of the film can reach up to 85% and the crystal size were around 300nm, the adhesion level between the film and substrate was 5B.