Evaluating the state of indium–tin oxide gels via estimation of their cohesive energy

Abstract

In the fabrication of metal oxide films by the solution process, it is very important to know the state of a gel. In this report, the type of for indium–tin oxide (ITO) gel was determined according to the cohesive energy for agglutinating a gel. We developed the new method of determining a gel’s state to elucidate the total cohesive energy of an ITO gel film and its components. We employed an optical method based on the Lifshitz–van der Waals theory and a contact angle measurement method based on the van Oss theory to estimate components of cohesive energy. The result showed that the van der Waals interaction was the dominant interaction in the agglutination of the ITO gel. This indicated that the ITO gel is a physical gel. This result coincided well with these obtained by conventional methods such as thermogravimetric–differential thermal analysis and resolvability tests. The new method will be very useful for evaluating the gel state nondestructively.