Role of Ethanolamine on the Stability of a Sol–Gel ZnO Ink

This work presents a detailed structural and chemical characterization of the system formed by zinc acetate dihydrate (ZAD) and ethanolamine (EA) with methoxyethanol (ME), in order to describe its stability. The origin of the mixture degradation during storage at room conditions is analyzed. Complementary computational (or theoretical) DFT calculations on the precursor formed in this reaction in ME and those of EA (free or in the same solvent) and in the presence or absence of CO2, light, or both simultaneously are also reported in order to clarify the relative weight of these factors in the degradation process. In all cases, the models were tested as potential energy minimum, and their photoabsorption spectra were simulated. The calculations show that the monomeric species formed in this process tend to assemble into dimers, which are more photosensitive and reactive than the monomer. Our results explain the experimental observations and provide a better understanding of the role played by EA, ME, and CO2 in the formation of ZnO and, consequently, allow for the optimization of the technological processes used to prepare these films.