Low Temperature Preparation Of Wide Band-Gap Metal Oxide Thin Films With Novel Designed Solution Processes

Abstract

Highly homogeneous crystalline TiO2 thin films were prepared by spin-coating a TiO2 nanoparticle aqueous dispersion at room temperature without further heat treatment. Using these films as electron transporting layers, inverted structure hybrid photovoltaic cells (TiO2/P3HT) and light-emitting diodes (TiO2/F8BT) were demonstrated. The performance of these devices show that a properly designed nanoparticle casting route can help avoid high temperature crystallization or sintering steps for TiO2 thin films, paving the road for their use in conjunction with plastic substrates. Post-annealing of TiO2/F8BT copolymer bilayer could remove the adsorbed hydroxyl groups in the bottom TiO2 while also made the F8BT copolymer diffuse into the TiO2 layer. Bulk heterojunction of electron-transporting TiO2 and light-emitting polymer was formed after post-annealing and the performance of TiO2/F8BT copolymer hybrid LEDs was largely improved. TiO2/F8BT hybrid LEDs show a promising brightness ~ 7000 cd/m2 and an outstanding current efficiency as high as 2 cd/A, which is three times higher than the efficiency of hybrid LEDs without the post-annealing treatment. MOD processed a-IGZO transistors have the basic characteristics of thin film transistors. The performance of a-IGZO TFT with the mobility of 3.4 cm2V-1s-1 shows the newly developed approach promising. The spincoating preparation of a-IGZO film is a rather simple process for transistor fabrication and therefore provides the possibility of low-cost manufacture of transparent TFTs with good performance.