Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 8Citation - Scopus: 9Tuning the Colour of Solution Processed Perylene Tetraester Based Oleds From Yellowish-Green To Greenish-White: a Molecular Engineering Approach(Elsevier, 2023) Aksoy, Erkan; Bozkuş, Volkan; Varlıklı, CananThree regioisomericaly pure 1,7-di-ethynyl bridged perylene-3,4,9,10-tetracarboxy tetrabutylesters functionalized with triisopropylsilyl-ethynylen (PTE1), phenyl-ethynylen (PTE2) and tetraphenylsilyl-ethynylen (PTE3) groups were synthesized. Photophysical, thermal, electrochemical, and solution processed electroluminescence (EL) behaviours were investigated in comparison with a basic perylene-3,4,9,10-tetracarboxy tetrabutylester (PTEref) structure. Stepwise π conjugation, allowed tuning the absorption and photoluminescence wavelengths of the PTEs without disturbing the photo, thermal and electrochemical stabilities; ≫10h, >250 °C, and >50 cycles, respectively. Electron mobility of PTE2 is measured to be more than 10-fold of the other PTE derivatives. Individual utilization of PTE derivatives as solid-state emitters in poly(N-vinylcarbazole) (PVK): 2-(4-Biphenylyl)-5-phenyl-1,3,4-oxadiazole (PBD) host matrix produced yellowish-green EL. Benefiting from higher electron mobiliy, PTE2 emitter presented the best device efficiency values with an EL maximum of 535 nm. Whereas dual doping of the synthesized PTEs with PTEref resulted in greenish-white light with increased stability. Although the emitting layer contained no red emitting component, optimization of the dual doping ratio of PTEref:PTE3 produced a colour rendering index value of 76 with Commission Internationale d'Eclairage coordinates of (0.29, 0.37).Article Citation - WoS: 19Citation - Scopus: 19Navigating Cie Space for Efficient Tadf Downconversion Woleds(Elsevier Ltd., 2020) Aksoy, Erkan; Danos, Andrew; Varlıklı, Canan; Monkman, Andrew P.High efficiency orange and green emitting perylene dyes have been synthesized and dispersed in an inert polymer host to form an optical downconversion layer. To avoid dye aggregation and allow controlled colour tuning, this layer was deposited in multiple low-concentration spin-coating steps, directly on top of a high performance blue thermally activated delayed fluorescence (TADF) organic light emitting diode (OLED). The orange downconversion layer partially absorbs the blue OLED emission, while emitting a complementary orange to give white light. However, as energy transfer between the TADF and perylene downconverter is based on emission and reabsorption, absorptive filtering of the blue OLED emission band necessitates the inclusion of an additional green-emitting perylene top-layer to achieve optimal white balance. The optimised white OLED fabricated in this way displayed excellent white colour balance (CIE x, y; 0.33, 0.33) with perfect stability, good colour rendering (CRI 80), and a high maximum efficiency (maximum EQE 17.2%) with minimal losses compared to the base blue OLED. This approach is widely applicable for generating white emission from any kind of blue OLED, and is compatible with a wide range of downconverting dyes and host materials.Article Citation - WoS: 30Citation - Scopus: 32Perylene-Embedded Electrospun Ps Fibers for White Light Generation(Elsevier Ltd., 2019) Güner, Tuğrul; Aksoy, Erkan; Demir, Mustafa Muammer; Varlıklı, CananPerylene dyes have been employed in the fabrication of white light due to their superior photophysical properties and relatively easy synthetic methods. However, their molecular aggregation in solid state is one of the main handicaps since it causes deviation in their optical properties and quenches photoluminescence quantum yields (Phi(f)). Investigation of the photophysical properties of a green (PTE), a yellow (PDI) and a new red (DiPhAPDI) emitting perylene derivative in solution, drop-casted films, polystyrene (PS) fibers and PS fibers embedded in poly (dimethyl siloxane) (PDMS) showed that PS:dye fibers prevent aggregation to some extend and allows high Of of dyes. The Of values of PTE, PDI and DiPhAPDI were all higher than 93.0% in solution and 84.8%, 94.3% and 73.6%, respectively in PS:dye fibers. Embedding the fibers in PDMS improved the photostabilities of the dyes two folds compared to their solution phases. The prepared dye containing fibers were combined together into a single PDMS film and utilized as a frequency conversion layer on a blue LED. Fabricated samples were found to show high color rendering index (>= 90), adjustable CCT (7500 K-5000 K), and power efficiency values exceeding 2001m/W depending on the used fiber amount in mass.