Exciplex‐based organic light‐emitting diodes with deep blue emission

Exciplex are generated at the heterojunction interface of electron donor and acceptor materials. Exciplex strategy can, thus, reduce molecular design difficulties for obtaining near-UV emission by selecting the appropriate electron donors and acceptors. Induced exciplex of Tris(4-carbazoyl-9-ylphenyl)amine (TCTA)/ 2,9-Dimethyl-4,7-diphenyl-1,10- phenanthroline (BCP) were applied to design deep blue organic light emitting diodes (OLEDs). BCP was used as an electron transport material and TCTA as a hole transporting material. The investigations carried out on planar-heterojunction have shown that recombination region was located at the vicinity of TCTA/BCP interface leading to exciplex formation. Furthermore, the thicknesses of BCP and TCTA layers play a key role in the control of the recombination zone and the emission color of the OLEDs. The electroluminescent spectra of planar-heterojunction exciplex-based OLEDs displayed deep blue emission at 423 nm with CIE coordinate of (0.16, 0.11). The emission of bulk-heterojunction exciplex-based OLEDs are also investigated showing that their emission is dominated by electroplex emission. The results demonstrate the feasibility of fabricating the efficient exciplex-based deep-blue OLED.