High T_g Triphenylamine-Based Starburst Hole-Transporting Material for Organic Light-Emitting Devices

Abstract

This paper reports the synthesis of a new starburst molecule, 4,4′,4′′-tris [(2,3,4,5-tetraphenyl)phenyl]phenylamine (TTPPPA) and its application as a hole-transporting material in organic light-emitting devices (OLEDs). Although TTPPPA has almost the same ionization potential as 1,4-bis(1-naphthylphenylamino)biphenyl (NPB), the TTPPPA-based device of ITO/TTPPPA/Alq 3 /LiF/Al yields much better efficiency of 5.3 cd/A and 4.3 lm/W than the standard ITO/NPB/Alq 3 /LiF/Al device (3.0 cd/A and 2.9 lm/W). The remarkable performance enhancement is attributed to a better balance of hole and electron injection in the TTPPPA-based device. Further, TTPPPA has a much higher glass-transition temperature (T g , 202 °C) than NPB (T g , 98 °C), suggesting that TTPPPA can be an alternative material to NPB especially for high-temperature applications of OLEDs and other organic electronic devices.

Synthesis and Investigation of the V‐shaped Tröger′s Base Derivatives as Hole‐transporting Materials

“…Materials depositeds uch way, however, demonstrate lower carrierm obility.T he decrease in mobility is generally attributed to the higher structural disorder that reduces intermolecular p-orbital overlap. Compared with other lowm olecular weight hole-transporting materials, [4,5,8,17,22,23] Trçger'sb ase phenylethenyl derivatives demonstrate comparatively high hole drift mobility.…”

Progress in Modification of Indium-Tin Oxide/Organic Interfaces for Organic Light-Emitting Diodes

“…263 A typical bilayer device with a configuration of ITO/TQTPA (60 nm)/Alq 3 (50 nm)/LiF (0.5 nm)/MgAg yielded a maximum current efficiency of 5.6 cd/A (with Alq 3 emission), which is much better (50% higher) than that of the prototypical NPB-based device (3.8 cd/A) with a similar device structure. 4 , 4 , 4 -tris[ (2 , 3 , 4 , 5 -tetraphenyl)phenyl] phenylamine (TTPPPA) has been applied as a HTM in organic light-emitting devices (OLEDs) 264 although TTPPPA has almost the same ionization potential as 1,4-bis(l-naphthylphenylamino)biphenyl (NPB), the TTPPPA-based device of ITO/TTPPPA/Alq 3 /LiF/Al yields much better efficiency of 5.3 cd/A and 4.3 lm/W than the standard ITO/NPB/Alq 3 /LiF/Al device (3.0 cd/A and 2.9 lm/W).…”

New Carbazole‐Based Hyperbranched Conjugated Polymer with Good Hole‐Transporting Properties

“…Generally, an OLED produces light via the recombination of electrons and holes, which are injected from electrodes on opposite sides of the electron‐emitting film. The performance of the devices is significantly influenced by the charge balance between electrons and holes from the opposite electrodes 6–9. With the efforts to achieve highly efficient and long lifetime devices, the structure of devices has been developed from single‐layer to multilayer, in which hole‐transporting or electron‐transporting layer is usually added to control and achieve the charge balance 10.…”

“…For an excellent hole‐transporting material (HTM), it should possess good thermal and morphological stability in its solid thin films, low energy carrier (to allow ease of charge injection), good optical transparency, and high hole mobility 11–13. Recent researches demonstrate that the adjustment of the structure of HTM from linear to dendritic is an effective approach to achieve good performance, since the highly branched and globular features of dendritic materials can benefit the efficient depression of the possible aggregation and the exciton formation, to improve the thermal stability and solubility, and form good morphologically thin film 9, 14–18. In comparison with dendrimers, hyperbranched polymers possess similar dendritic structure, enjoy the same good properties, moreover, even demonstrate more advantages, especially the convenient preparation in a large scale by one‐pot and single reaction procedure 19.…”