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 (In 2 O 3 ), chlorination, chelation, and steaming treatment, was established. Indium trichloride (InCl 3 ) was quantitatively synthesized by the reaction of In 2 O 3 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) 2 Cl 2 ) and spin coated on a glass plate, followed by steaming and heating to obtain ITO films containing 10 wt% tin oxide. In 2 O 3 was crystallized in c-, rh-, and o-In 2 O 3 . This film showed a resistivity of 9.7 Ωcm and a transparency of 86%. Highlights ITO films were prepared from In(etac) 3 and Sn(acac) 2 Cl 2 . Steaming and heating treatments were performed to remove organic ligands. In 2 O 3 was recycled by chlorination, chelation, and heating.