Synthesis of indium tin oxide films from ethyl acetoacetonato complexes at low temperatures

A novel recycling system for indium in indium tin oxide (ITO), which comprises the dissolution of indium oxide (In2O3), chlorination, chelation, and steaming treatment, was established. Indium trichloride (InCl3) was quantitatively synthesized by the reaction of In2O3 with hydrochloric acid (HCl) and furnished tris(ethyl acetoacetato)indium (In(etac)3) in a high yield by a subsequent reaction with ethyl acetoacetate (Hetac). In(etac)3 was mixed with bis(acetylacetonato)tin dichloride (Sn(acac)2Cl2) and spin coated on a glass plate, followed by steaming and heating to obtain ITO films containing 10 wt% tin oxide. In2O3 was crystallized in c-, rh-, and o-In2O3. This film showed a resistivity of 9.7 Ωcm and a transparency of 86%.