Synthesis and characterization of triple-azacrown ethers containing fluorene-cored derivatives: application as electron injection layer for significantly enhanced performance of PLEDs

Abstract

To enhance electroluminescence of polymer light-emitting diodes (PLEDs) using an environmentally stable aluminum cathode, we designed a novel water/alcohol-soluble electron injection material, FTC, composed of a fluorene core and triple azacrown ether terminals. FTC significantly enhances the emission performance of PLEDs [ITO/PEDOT:PSS/EML/EIL/Al] when used as the electron injection layer (EIL), especially in the presence of metal carbonates and metal acetates. The metal carbonate-doped devices showed the best performance due to their higher dissociation rate than metal acetates. In particular, the device using K 2 CO 3 doped-FTC as the electron injection layer (EIL) exhibited significantly enhanced performance compared to the device without an EIL. For the device based on PF-Green-B as the emitting layer, the performance was significantly enhanced to 17 460 cd m À2 , 21.58 cd A À1 , and 12.42 lm W À1 , respectively, from 1220 cd m À2 , 0.72 cd A À1 , and 0.27 lm W À1 for the non-FTC device. Using HY-PPV as the emitting layer, the device performance was also significantly enhanced to 10 990 cd m À2 , 6.93 cd A À1 , and 5.27 lm W À1 , respectively, from 680 cd m À2 , 0.07 cd A À1 , and 0.03 lm W À1 for the non-EIL device. The results indicate that FTC with metal cations is an excellent electron injection candidate for the performance enhancement of PLEDs with a high work function Al cathode. † Electronic supplementary information (ESI) available: Synthesis and characterization of monomers, the 1 H NMR spectra, and thermal, optical, electrochemical and optoelectronic properties of FTC, and the proposed chemical structure of doped-FTC. See

Hydroxyethyl cellulose filled with M2+ chelate complexes with ethylenediaminetetraacetic acid (EDTA) as an effective electron-injection layer for polymer light-emitting diodes

“…The chelation and binding of ions by appropriate chelating agents (chelators) increased the interfacial dipole to facilitate electron injection from the cathode [20,41]. Polar pendant groups in polymers, such as ether, amino, crown or azo-crown ether groups, also demonstrated this characteristic by binding with ions [20,41,44,45]. The application of a stable pseudo-metallic state as an intermediate step for effective electron injection opens an efficient way to enhance polymer light-emitting diodes performance.…”

Nanostructuring with Surfactants: The Self-Assembly of a New Poly(thiophene-phenylene) Conjugated Polymer Bearing Azacrown Ether Pendant Groups

“…The use of CP with pendant crown ether groups shows great potential and opens new technological possibilities since they combine the optoelectronic properties of CP and the sensitivity/selectivity of the crown ether moieties. This approach has been successfully demonstrated for a wide range of applications, such as chemical − and biological , sensors, polymer light-emitting diodes, − thermoresponsive materials for supramolecular gels, and bulk-heterojunction polymer solar cells . The dynamic and reversible properties of CPs make them suitable to monitor minor changes in the system and can be easily followed by optical methods, such as photoinduced electron transfer (PET), aggregation induced emission (AIE), and aggregation caused quenching (ACQ). ,− A multifunctional fluorene-based material containing triple azacrown ether, 2,4,7-tri­[4-(monoaza-15-crown-5)­styryl]-9,9-dihexylfluorene, was synthesized and successfully used as a chemosensor toward Fe 3+ , and also to enhance the electroluminescence of polymer light-emitting diodes (PLEDs) using an environmentally stable aluminum cathode .…”

“…This approach has been successfully demonstrated for a wide range of applications, such as chemical − and biological , sensors, polymer light-emitting diodes, − thermoresponsive materials for supramolecular gels, and bulk-heterojunction polymer solar cells . The dynamic and reversible properties of CPs make them suitable to monitor minor changes in the system and can be easily followed by optical methods, such as photoinduced electron transfer (PET), aggregation induced emission (AIE), and aggregation caused quenching (ACQ). ,− A multifunctional fluorene-based material containing triple azacrown ether, 2,4,7-tri­[4-(monoaza-15-crown-5)­styryl]-9,9-dihexylfluorene, was synthesized and successfully used as a chemosensor toward Fe 3+ , and also to enhance the electroluminescence of polymer light-emitting diodes (PLEDs) using an environmentally stable aluminum cathode . Multilayer PLEDs were constructed with an electron injection layer (EIL) based on a water/alcohol soluble copoly­( p -phenylene) with pendant azacrown ether and ethylene glycol ether groups doped with metal carbonate .…”

Hole‐buffer polymer composed of alternating p‐terphenyl and tetraethylene glycol ether moieties: Synthesis and application in polymer light‐emitting diodes

“…We have been developing new electron‐injection materials to modify high work‐function cathode such as aluminum and hole/electron transporting materials to improve carrier balance and device performance . In this study, we attempted a different approach to improve device performance of PLEDs.…”