Theoretical studies on electronic structures and photophysical properties of anthracene derivatives as hole-transporting materials for OLEDs

• Electronic structures and photophysical properties of HTM were theoretically investigated.
• Structural modification of HTMs affects luminescent properties of device.
• The excellent charge mobility enhances luminescent properties.
• Triphenylamine is a promising donor group for HTM.
• The studied compounds are suitable as HTM in electroluminescent device.

The electronic structures and photophysical properties of anthracene derivatives as hole-transporting materials (HTM) in OLEDs have been studied by DFT and TD-DFT methods. Thiophene and triphenylamine (TPA) moieties are used as substituents in anthracene based HTMs providing FATn and FAPn compounds (n = 1–2), respectively. The calculated electronic levels by B3LYP show proper energy matching of FAPn and hole-injecting layer (HIL), indicating that the hole-transports of the FAPn compounds are better than the FATn compounds. The photophysical properties calculated by TD-B3LYP elucidate that TPA in FAPn compounds acts as electron donating group and induces charge transfer character in the absorptions. Furthermore, the calculated ionization potential (IP), electron affinity (EA) and reorganization energies also revealed that the extended FAP2 compound has the highest charge-transporting ability among the studied compounds. The calculated results are consistent to our experimental observations showing that FAP2 exhibits bright fluorescence with highest quantum yield in electroluminescent devices. Understanding of these properties is useful for further design of new HTMs of desired properties, such as high efficiency and stability.

TOC. A schematic of OLED energy diagrams that show the position of the boundary orbital energy levels in each layer forming the device.Figure optionsDownload as PowerPoint slide