Diflavonols as single emitters for polymer-based WOLEDs

The spectral peculiarities of polymer/dye solid mixtures on the base of PEPCa polymer (polyepoxypropylcarbazole) as matrix and DFOM (3,7-dihydroxy-2,8-diphenyl-4H,6H-pyrano[3,2-g] chromene-4,6-diones) as emitter were investigated. Peculiarities intramolecular proton transference after the excitation of molecule, incident to this material, allows one to create emitting layer with emission spectrum close to white light and using only one luminophore. Spectral behavior of investigated compounds proves the presence of excitation energy transfer from the PEPCa matrix to the DFOM molecules, which is necessary for effective use of the excitation energy and forming luminescence curve needed. Luminescence of the investigated films demonstrates color characteristics CRI 54 and CIE (0.33, 0.42) which gives a possibility to consider such systems as promising in the context of developing White OLED emitters

Photophysical properties of novel luminescent dyes: difluoroborate complexes of benz[c,d]indole derivates

The fluorescence and absorption spectra of new boron-containing dyes have been studied. Using standard techniques, the quantum yield and fluorescence decay characteristics for these substances in liquid solutions were determined. It has been shown that these dyes in solutions are characterized by high quantum yield. The full interpretation of the absorption and fluorescence spectra has been done using quantum-chemical calculations. It is established that superposition of the fluorescence spectra dyes covers almost the entire visible range of wavelengths. The absorption region can be varied by changing the end groups in these dyes. Dyes with these properties can be used for creation of white OLEDs

Different effect of polymer-incorporated nanoparticles of Au and Ag on hematoporphyrin interaction with graft polymers

One of the ways to improve the efficiency of photodynamic therapy is to enhance the accumulation of the photosensitizer (PS) in the tumor; for this, either polymers or metal nanoparticles (NP) could be used. Here we studied the effect of Au and Ag nanoparticles (AuNPs and AgNPs, respectively) synthesized in situ in solution of non-charged and anionic polymers on spectral properties of PS hematoporphyrin (HP) as well as on ¹O₂ generation by this compound (revealed by ¹O₂ emission at 1275 nm). The star-like copolymer Dextran-graft-Polyacrylamide (D-g-PAA) and its anionic form (D-g-PAAan) were used as polymer matrices for nanosystems preparation. Absorption and fluorescence spectra show that HP molecules bind to D-g-PAA and D-g-PAAan in water that leads to the destruction of HP aggregates; these changes are accompanied by increase of ¹O₂ generation. Meanwhile, in the presence of polymers with incorporated AgNPs (D-g-PAA/Ag and D-g-PAAac/Ag) the mentioned effect is stronger as compared to corresponding polymers without incorporated NPs. Thus AgNPs affect the graft polymers interaction with HP. Contrarily, the presence of both polymers with incorporated AuNPs enhances HP aggregation; besides, in the case of non-charged polymer with gold nanoparticles D-g-PAA/Au, Au nanoparticles induce appearing of different HP form, presumably protonated one. Effect of Ag and Au nanoparticles on fluorescent properties of HP is mainly determined by the effect of these NPs on aggregation of HP (and, in the case of D-g-PAA/Au, by appearing of different HP form). As for HP-sensitized singlet oxygen luminescence, effect of AgNPs is also mainly related to aggregation destruction, while this of Au nanoparticles could have other mechanisms as well

Optical and unique photovoltaic properties of 2-cyano-3-(4-dimethylaminophenyl)-2-propentioamide dye deposited on the gilded substrate

Optical, dark electrical and photoelectrical properties of the organic dye 2-cyano-3-(4- dimethylaminophenyl)-2-propentioamide (solutions in different solvents and films obtained by vacuum deposition of the dye layer on quartz and gilded quartz substrates) were studied. In the case of dye films deposited on the gilded substrate new effects have been noted as compared with solutions and films deposited on glass substrates. It is argued that these effects could be related to the ordering of the dye molecule dimers with possible aggregate formation in films induced by interaction with gilded substrate. The observed effects can be used for development of a new type of solar cell as well as for design of molecular photovoltaic elements for nanoelectronics and nanophotonics.Досліджено оптичні, темпові та фотоелектричні властивості органічного барвника 2-ціано-3-(4-диметиламінофеніл)-2-пропентіоамід (розчини у різних розчинниках та плівки, нанесені методом вакуумного випаровування як на кварцові, так і позолочені кварцові підкладинки). У випадку плівок барвника, нанесеного на позолочену підкладинку, з’являються нові ефекти у порівнянні з розчинами барвника або ж плівками, нанесеними на скло. Припускається, що ці ефекти пов’язані з певним просторовим упорядкуванням димерів молекул барвника і, можливо, утворенням агрегатів, що спричинено взаємодією з позолоченою підкладинкою. Ефект, що спостерігається, може бути використаний як для створення нового типу елементів сонячних батарей, так і для дизайну молекулярних фотовольтаїчних елементів для наноелектроніки та нанофотоніки.Исследованы оптические, темповые и фотоэлектрические свойства органического красителя 2-циано-3-(4-диметиламинофенил)-2-пропентиоамид (растворы в разных растворителях и пленки, нанесенные методом вакуумного испарения как на кварцевые, так и на позолоченные кварцевые подложки). В случае пленок красителя, нанесенного на позолоченную подложку, появляются новые эффекты по сравнению с растворами красителя или пленками, нанесенными на стекло. Предполагается, что эти эффекты связаны с определенным пространственным упорядочением димеров молекул красителя и, возможно, образованием агрегатов, вызванным взаимодействием с позолоченной подложкой. Наблюдаемые эффекты могут быть использованы как для создания нового типа элементов солнечных батарей, так и для дизайна молекулярных фотовольтаических элементов для наноэлектроники и нанофотоники