Synthesis of n‐type [60]Fullerene Derivatives with Sterically Bulky tert‐Butyl Groups for Vacuum Deposition Processes. Issue 17 (3rd August 2022) - Shibuya, Hiromasa
Abstract: [60]Fullerene derivatives with high thermal stability can be used for vacuum deposition under heating to fabricate thin films for organic electronic devices. Here, we investigated the thermal stability of [60]fullerene derivatives with various bulky substituents for thermal evaporation under vacuum by means of thermogravimetric analysis under reduced and normal pressure. We found sterically bulky groups such as tert ‐butyl groups of [60]fullerene derivatives lowered the vacuum deposition temperature. Also, we performed isothermal thermogravimetric analysis to examine the long‐term thermal stability of the designed compounds under heating conditions. Furthermore, we investigated the UV‐Vis absorption patterns of the deposited films. Absorption in the blue wavelength range, which was attributed to intermolecular HOMO–LUMO transitions among the molecular orbitals of adjacent [60]fullerenes, was dramatically modified. These results were associated with the prevention of aggregation among neighboring [60]fullerene by the sterically bulky groups. This concept could contribute to expanding the use of evaporable [60]fullerene derivatives in organic thin‐film electronics research fields. Abstract : Thermally stable [60]fullerene derivatives with various bulky substituents for thermal evaporation under vacuum were synthesized and investigated with thermogravimetric analysis under reduced and normal pressure. Sterically bulky groups such as tert ‐butyl groups in [60]fullerene derivatives lowered the vacuum deposition temperature and reduced absorption in the blue wavelength range for optical device application.