Design and preparation of In2O3-based multi-layer functional films

Leveraging the conductivity of In 2 O 3 and the wear resistance and anti-corrosion behaviour of SiO 2 and TiO 2 , In 2 O 3 , In 2 O 3 /SiO 2 and In 2 O 3 /TiO 2 films were prepared via magnetron sputtering to meet the transparency, conductivity, wear resistance and corrosion resistance requirements for external screens of wearable devices. The films exhibited excellent sheet resistance of 13–28 Ω·sq −1 , which fully met the conductivity criteria. Owing to the light interference effect, the average transmittance of the In 2 O 3 film (77%) was higher and lower than those of the In 2 O 3 /TiO 2 (69%) and In 2 O 3 /SiO 2 (83%) films, respectively. After soaking in sweat solutions for 48 h, the In 2 O 3 and In 2 O 3 /SiO 2 films maintained their optical and electrical properties and the In 2 O 3 /TiO 2 film was partially peeled off in the acid solution. The low transmittance and corrosion resistance of the In 2 O 3 /TiO 2 film were due to severe oxygen deficiency in the TiO 2 layer, indicated by the certain amount of Ti 2 O 3 and metal Ti in XPS. The wear failure time of the In 2 O 3 /SiO 2 film (42 h) was greater than those of the In 2 O 3 (30 h) and In 2 O 3 /TiO 2 (24 h) films because of its hard SiO 2 top layer. Based on the ‘parallel sheet resistance principle’, the resistivity of the double-layer films was mainly attributed to the conductive In 2 O 3 layers. The wear and corrosion resistances were ascribed to the top passive transparent layers, in which the SiO 2 layer showed its excellent optical and electrical performance stabilities before and after corrosion and wear resistance functions. With its commonly high transparency and conductivity as well as its high wear and corrosion resistances, the In 2 O 3 /SiO 2 film exhibits application potential for external screens of wearable devices.