A review of fused-ring carbazole derivatives as emitter and/or host materials in organic light emitting diode (OLED) applications

This review focuses on fused-ring carbazole derivatives, their molecular design, electronic and photophysical properties, and in particular their applications as the emitter and/or the host material in the emitting layer of organic light emitting diodes (OLEDs), with emphasis on recent developments. This review is timely because of the rapidly expanding research into fused-ring carbazoles, predominantly indolocarbazole, indenocarbazole, benzofurocarbazole, benzothienocarbazole and diindolocarbazole derivatives. To our knowledge this class of materials has not been reviewed previously. The appeal of fused-ring carbazoles is their extended π-electron systems with good thermal stability, tunable frontier orbital energies that enable a wide gamut (red, green, blue and white) emission colour, high photoluminescence quantum yields, and versatility for chemical functionalisation at different sites, leading to outstanding OLED efficiencies. This review is divided into sections according to the molecules’ role in OLEDs: namely, as conventional luminescent emitters – especially in the deep-blue region; as state-of-the-art hosts for phosphorescent iridium-based emitters; as thermally activated delayed fluorescence (TADF) emitters with high external quantum efficiency; and as multiresonance (MR) emitters with unprecedented high colour purity. We conclude by highlighting the challenges and the great opportunities for fused-ring carbazole derivatives in OLEDs and other optoelectronic applications

Tetraphenylsilane group containing carbazoles as high triplet energy host materials for solution-processable PhOLEDs

WOS: 000362850500002A series of solution processable, wide band-gap host materials composed of carbazole and tetraphenylsilane groups were designed and synthesized. Their thermal, electrochemical, and photophysical properties were fully investigated. The introduction of bulky tetraphenylsilane and tert-butyl groups around the carbazole led to high glass transition temperatures (T-g) between 120 and 204 degrees C. The triplet energies (E-T) of the synthesized materials were examined by low temperature (77 K) photoluminescence studies and determined as E-T > 2.6 for all compounds. Phosphorescent organic light-emitting devices with the ITO/PEDOT:PSS/EML/TPBi/Cs2CO3/Al device structure were fabricated by using synthesized materials as the host and two kinds of phosphorescent emitters, FIrpic and Ir(ppy)(3), as the guests. The highest luminous and power efficiency values obtained by using FIrpic were 3.6 cd A(-1) and 1.48 lm W-1, respectively, with commission International de I'Eclairage (CIE) coordinates of (0.17, 0.36), whereas these values were 7.8 cd A(-1) and 2.9 lm W-1 for the device structure when Ir(ppy)(3) was used as the guest [CIE (0.28, 0.62)].Scientific and Technological Research Council of Turkey (TUBiTAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [113Z253]This work was supported by the Scientific and Technological Research Council of Turkey (TUBiTAK) (Project #: 113Z253). The authors would like to thank Dr Armagan Kmal for productive discussions on the numerical calculations, which were performed at TUBITAK ULAKBIM, High Performance and Grid Computing Center (TRUBA Resources)

Highly efficient supercapacitor using single-walled carbon nanotube electrodes and ionic liquid incorporated solid gel electrolyte

2nd International Conference on Science and Engineering of Materials (ICSEM) -- JAN 06-08, 2018 -- Sharda Univ, Greater Noida, INDIAWOS: 000445227400010Gel polymer electrolyte (GPE) comprising a low viscosity ionic liquid, that is, 1-propyl-3-methyl imidazolium bis(trifluoromethyl sulfonyl)imide (PMI-TFSI, viscosity 38 cP at 20 degrees C) and a polymer, that is, polyvinyl alcohol (PVA) have been prepared using solution cast technique and characterized by impedance spectroscopy, X-ray diffraction, differential scanning calorimetry, optical microscopy, and Fourier transform infrared spectroscopy. Blending PMI-TFSI with PVA matrix hindered the crystallinity of polymer matrix and presented remarkable enhancement in electrical conductivity with a conductivity maxima at 250 wt% PMI-TFSI. The prepared electric double-layer capacitor using single-walled carbon nanotube as symmetric electrodes and PVA:250 wt% PMI-TFSI as GPE presented a capacitance value of about 28 F g(-1).TUBITAK fellowship, Government of TurkeyThe author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by TUBITAK fellowship, Government of Turkey

Enhanced capacitive behaviour of graphene based electrochemical double layer capacitors by etheric substitution on ionic liquids

WOS: 000540455700019In this study, we report the effect of etheric substituents in imidazolium and ammonium based ionic liquids (IL) on the performance of electrochemical double layer capacitors (EDLC) consisted of gel polymer electrolyte (GPE) and reduced graphene oxide (RGO) electrode. GPEs contain poly (vinylidene fluoride-hexafluompropylene) (PVDF-HFP) and the ILs. Ammonium and imidazolium based ionic liquids (ILs) differ by their length of etheric groups and etheric group contents, respectively. According to the cyclic voltammetry, galvanostatic chargedischarge and electrochemical impedance spectroscopy measurements, longer etheric group substituted {N-methyl-2- (2-methoxyethoxy)-N,N-bis [2- (2-methoxyethoxy)ethyl] ethan-1-aminium bis(tri-fluoromethanesulfonyl)imide (AMEt-TFSI) and ether substituted (3-allyl-1-[2-(2-methoxyethoxy)ethyl]-1H-imidazole-3-ium bis(trifluommethanesulfonyeimide (AL3IL-TFSI), tender specific capacitances of 250 Fg(-1) and 238 Fg(-1) and energy density values of 61.36 wh kg(-1) and 61.56 wh kg(-1), respectively.Ministry of Development of TurkeyTurkiye Cumhuriyeti Kalkinma Bakanligi [16 DPT002, 11DPT003]; Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114M508]S.S. and C.V. would like to thank Prof. Dr. Pramod Singh Kumar and Prof. Dr. Yogesh Kumar for their theorical contribution during the evaluation of EDLC results. S.O and C.V. are thankful to Dr. H. Q. Nimal Gunaratne for the productive discussions and contributions related with the synthesis and characterization of the ILs. We would also like to acknowledge the Ministry of Development of Turkey for the project supports for some of the consumables (project #: 16 DPT002) and infrastructure (project #: 11DPT003). H.D. and C.V. thank to the project support of Scientific and Technological Research Council of Turkey (TUBITAK) (Project #: 114M508) for the synthesis and characterizations of graphene derivatives and for the fellowship support for HD. We would also like to thank the Izmir Institute of Technology, the Centre for Materials Research for BET analysis

Pediatric Varicella-related Hospitalization in Turkey Between 2008 and 2018: Impact of Universal Single Dose Varicella Vaccine (VARICOMP Study)

Background: A single-dose varicella vaccine at 12 months of age was introduced to the National Immunization Program in February 2013 in Turkey. This study aimed to evaluate varicella-related hospitalization in children and the impact of a single-dose live attenuated varicella vaccine over the first 5.5 years of introducing a universal varicella vaccination. Methods: We analyzed data collected from the medical records of children 15-year-old groups (P < 0.01 and P < 0.05). The mean age was higher during the post-vaccine period than during the pre-vaccine period (P < 0.001). The absolute number of secondary bacterial infections (P < 0.01), respiratory complications (P < 0.01), and neurological complications (P < 0.001) was significantly lower during the post-vaccine period. The incidence of severe varicella was lower during the post-vaccine period than during the pre-vaccine period (P < 0.001). Conclusions: After 5.5 years of routine single-dose varicella vaccine use, we observed the impact of varicella vaccination on the incidence of varicella-related hospitalizations, especially in the target age group. However, we did not observe herd protection in the other age groups. The implementation of a second dose of the varicella vaccine in the National Immunization Program would help control disease activity