Photonics / Fotonik
Permanent URI for this collectionhttps://hdl.handle.net/11147/2590
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Article The Effect of Imide Substituents on the Excited State Properties of Perylene Diimide Derivatives(Fırat Üniversitesi, 2022) Aksoy, Erkan; Danos, Andrew; Li, Chunyong; Monkman, Andrew; Varlıklı, CananSolid state optical properties of fluorescent materials are important for many photonic devices such as organic light emitting diodes, frequency down-converters or luminescent solar concentrators. Perylene diimides (PDIs) represent one of the most popular organic semiconductors which find application in such photonic device applications. In this study, photophysical properties of two dibrominated PDI (DiBrPDIs), one of which contains a branched alkyl chain (2-ethylhexyl, 2-EH) and the other with an aromatic substituent (diisopropylphenyl, DIA) at the imide positions are comparatively studied. We report their absorption and photoluminescence, lifetime and photoluminescence quantum yield (PLQY), as well as photoinduced absorption properties (PIA) examined by fs-transient absorption spectroscopy. Having the same ? conjugated system, DiBrPDIDIA and DiBrPDI-2EH exhibited identical absorption and photoluminescence (PL) spectra in chloroform (?abs:527 nm and ?PL:552 nm). However, in film phase, DiBrPDI-DIA (?PL-DIA:596 nm; PLQY:73.4%) presented a shorter PL wavelength with a higher PLQY than that of DiBrPDI-2EH (?PL-2EH:649 nm; PLQY:36.7%). Bond lengths and core bending angles of PDI derivatives were calculated using Chem3D pro software. It was determined that the 2,6-diisopropylphenyl group in DiBrPDI(DIA) extends a distance of about 6.8 Å out from the imide positions, providing more effective steric protection from aggregation than the smaller 2EH group.Article Citation - WoS: 6Citation - Scopus: 7Perylene Based Solution Processed Single Layer Woled With Adjustable Cct and Cri(MDPI, 2021) Bozkuş, Volkan; Aksoy, Erkan; Varlıklı, CananIn solution processed single layer white organic light emitting diode (WOLED) applications, the choice of host matrix and optimization of dopant levels represent two crucial parameters to consider. In this work, poly(N-vinylcarbazole) (PVK): 2-(4-Biphenylyl)-5-phenyl-1,3,4-oxadiazole (PBD) and PVK:1,3-bis[(4-tert-butylphenyl)-1,3,4-oxadiazolyl] phenylene (OXD-7) matrices are used as hosts for perylene based devices. PVK:PBD presented better compatibility and lower turn-on voltages compared to PVK:OXD-7. Benefiting from the exciplex emission observed at 630 nm, a color rendering index (CRI) value of 90 is reached with the device containing PVK:PBD as the host and 0.1 wt.% of an orange emitting perylene derivative, i.e., PDI. Introduction of the perylene based green emitter, i.e., PTE, in this emitting layer not only caused a fading in the exciplex emission, but also resulted in disappearance of the electroplex peak at 535 nm, which is detected between PVK:PBD and PTE in bare PTE containing devices. Full visible range coverage is achieved by optimizing the PDI:PTE ratio. WOLED containing PVK:PBD:0.06 wt.% PDI:0.03 wt.% PTE presented high CRI (>= 95) and adjustable correlated color temperatures (CCT, 3800 K-5100 K).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.Conference Object Citation - WoS: 9Citation - Scopus: 11White Led Light Production Using Dibromoperylene Derivatives in Down Conversion of Energy(Canadian Science Publishing, 2018) Aksoy, Erkan; Demir, Nuriye; Varlıklı, CananPerylene derivatives of N,N′-bis(2,6-diisopropylphenyl)-1,6(7)-dibromoperylene-3,4,9,10-tetracarboxylic diimide (DBrPDI) and 1,7-dibromo perylene-3,4,9,10-tetracarboxylic acid butyl ester (DBrPTE) were synthesized, and their structural and optical characterizations were explored. Both DBrPDI and DBrPTE, which were utilized as wavelength converters on a GaN/InGaN based blue LED, were singlet sensitizers and had molar absorptivity constants around 104 Lmol-1cm-1. The blue LED that was used had Commission internationale de l'eclairage (CIE) coordinates of x, y = 0.13, 0.06; power and luminous efficiencies of 2.7 lm/W and 6.6 cd/A @5 mA, respectively. Because the fluorescence quantum yield of DBrPDI was much higher than that of DBrPTE, a meaningful white light efficiency was obtained with the diimide derivative. The use of DBrPDI resulted in white light with CIE coordinates of x, y = 0.34, 0.29 and luminous efficiency of 6.35 cd/A @5 mA, respectively. Using DBrPDI in a resin matrix resulted in more than three orders of magnitude increase in the luminous efficiency value (23.0 cd/A @5 mA) while the CIE coordinates remained the same. Whenever the applied current reached 20 mA, a CRI value of Ra = 90 was obtained.