Thermal stability in oligomeric triphenylamine/tris(8-quinolinolato) aluminum electroluminescent devices

Abstract

Thermal stability of the electroluminescent (EL) devices using various hole-transporting materials based on triphenylamine, and a typical emitting material, tris(8-quinolinolato) aluminum has been systematically studied. The thermal stability of the EL devices is clearly seen to depend on the glass transition temperature (Tg) of the hole-transporting material. The highest thermal stability up to 155 °C is obtained in the device using the pentamer of triphenylamine. It has been found that the linear linkage of triphenylamine is useful to attain high Tg rather than the branch linkage.

The chemistry of electroluminescent organic materials

“…The main characteristics of materials used as ETLs are: (i) they have large electron affinity and high electron mobility for efficient injection and transport of electrons and (ii) they have large exciton energy in order to prevent the energy transfer of the excitons, which are produced by charge recombination within the EML, to the ETL [180]. Besides, they are preferentially amorphous solids in order to have good film-forming ability [181].…”

Real-Time Observation of Temperature Rise and Thermal Breakdown Processes in Organic LEDs Using an IR Imaging and Analysis System

“…Optical systems, [9,10] microanalytical systems, [11] microelectronic devices such as transistors [12±15] and light-emitting diodes, [16] and Bragg reflectors for photo-pumped plastic lasers [17] have been realized with soft lithography. There are several advantages of using soft lithography compared to conventional photolithography: it is less costly, has no optical diffraction limit, allows control of the chemistry of a patterned surface, does not expose the sample to high-energy radiation, and can easily be applied to non-planar surfaces.…”

Simple model-free estimation of orientation order parameters of vacuum-deposited and spin-coated amorphous films used in organic light-emitting diodes

“…Figure 1 shows the chemical structures of the main OLED materials used in this study including -triphenylbiphenyl-4,4A-diamine) (TPT1), and 2,7-bis(9,9-spirobifluoren-2-yl)-9,9-spirobifluorene (TSBF), which have glass transition temperatures (T g ) of 60, 96, 110, 144, and 231°C, respectively. [9][10][11][12] For each material, we fabricated vacuum-deposited films with thicknesses of 20, 50, and 100 nm on fused silica and Si(100) substrates at a deposition rate of 2 Å=s under a vacuum of <1 × 10 −3 Pa. Spin-coated films were also fabricated on the same types of substrates using solutions of each material in chloroform (15 mg=mL) at spin speeds of 1000, 3000, 5000, and 7000 rpm, followed by mild baking under nitrogen atmosphere for 30 min on a hot plate at a temperature lower than T g : 50°C for TPD and 80°C for the other materials. We measured the absorption spectra of all the sample films on fused silica substrates using a spectrophotometer (Shimadzu UV2450).…”