A Study on the Initial Stage of 2,5-Diiodothiophene Monomer Deposition for OLED Display

摘要

Polythiophenes, oligothiophene, and their other derivatives have been paid attention to for organic display applications or bio-sensing device applications since they show very interesting electrical and optical properties as well as excellent environmental stabilities. However, they are very expensive, and hence instead of directly depositing them, 2,5-diiodothiophene monomer has been alternatively deposited and polymerized to polythiophenes during device processes for applications. In this study, gold substrate was deposited with 2,5-diiodothiophene, and Temperature Programmed Desorption was carried out increasing temperature from the liquid nitrogen temperature to 800K to characterize its chemical desorption reactions on the substrate. 2,5-diiodothiophene was characterized by its 82, 83,127, 164, 209 and 210 atomic mass unit(amu) during desorption, and in this study, 82 amu was especially paid attention to because of showing typical characteristics of 2,5-diiodothiophene. 82 amu developed two desorption peaks at 220K and 260K competitively. 260K peak increased as Langmuir increased, while 220K peak showed an incubation period of Langmuir amount to start to appear as Langmuir increased. Hence it was concluded that 260K peak was related to the adsorption of 2,5-diiodothiophene on pure gold surface, and that dose for depositing one monolayer of 2,5-diiodothiophene was greater than 0.5 Langmuir.