A facile method is reported which involves blending a conjugated electron-extraction polymer with photoactive materials to simplify the fabrication process.

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We present an investigation of deep-blue fluorescent polymer light-emitting diodes (PLEDs) with a novel functional 1,3,5-triazine core material (HQTZ) sandwiched between poly(3,4-ethylene dioxythiophene):poly(styrene sulfonic acid) layer and poly(vinylcarbazole) layer as a hole injection layer (HIL) without interface intermixing. Ultraviolet photoemission spectroscopy and Kelvin probe measurements were carried out to determine the change of anode work function influenced by the HQTZ modifier. The thin HQTZ layer can efficiently maximize the charge injection from anode to blue emitter and simultaneously enhance the hole mobility of HILs. The deep-blue device performance is remarkably improved with the maximum luminous efficiency of 4.50 cd/A enhanced by 80% and the maximum quantum efficiency of 4.93%, which is 1.8-fold higher than that of the conventional device without HQTZ layer, including a lower turn-on voltage of 3.7 V and comparable Commission Internationale de L'Eclairage coordinates of (0.16, 0.09). It is the highest efficiency ever reported to date for solution-processed deep-blue PLEDs based on the device structure of ITO/HILs/poly(9,9-dialkoxyphenyl-2,7-silafluorene)/CsF/AL. The results indicate that HQTZ based on 1,3,5-triazine core can be a promising candidate of interfacial materials for deep-blue fluorescent PLEDs.

Inspired by the electron-transfer process during oxidation of phenol and its derivatives, a novel hole-transport material (HTM) BHQTZ based on 1,3,5-triazine crosslinked 2,5-dibromohydroquinone is spin coated as the hole-transport layer (HTL) in polymer light-emitting diodes and shows efficient hole-transport properties. This result provides a promising scaffold and concept for the design and feasible synthesis of HTMs and the mechanism is based on the electron transfer during oxidation of BHQTZ, which is different from traditional electron-transport materials based on 1,3,5-triazine.

Two homopolymers of triphenylamine and carbazole grafting silafluorenes (PSF-TPA and PSF-Cz) were synthesized and their electroluminescence properties were investigated in this paper.