Electroluminescence in unconjugated polymers based on poly(arylene phthalide) films

Abstract

We discuss the results of measurements of the optical characteristics of thin organic films of unconjugated poly(arylene ether ketone) polymer. We have observed persistent electroluminescence for this polymer. We have established an interrelationship between the polarity of the voltage applied to the experimental structure and the electroluminescence spectrum.Quests for organic light-emitting materials having electrophysical properties that are stable over time and also having an electroluminescence (EL) emission spectrum close to the ultraviolet range are still timely today. This is especially connected with the problem of designing "blue" organic light-emitting diodes (OLEDs) capable of continuously operating for time intervals equal to those for "red" and "yellow" OLEDs.Moreover, recently there has been a steady trend toward seeking hybrid organic structures whose optical emitter properties might be controlled by alternative methods, such as by an external magnetic field or a change in polarity.Accordingly, in this work we investigated the electroluminescent properties of polymers having a wide bandgap, connected with the possibility of a blue shift of the emission region. Furthermore, in organic materials with a bandgap width of about 4 eV, the probability is significantly higher for realizing transport levels having a complex electron energy spectrum.As the objects of investigation, we chose polymers from the poly(arylene phthalide) class: poly(arylene ether ketone) copolymers. A feature of these polymers is the lack of conjugation of p electrons in the skeletal portion of the molecule. Therefore the bulk conductivity of these polymers is extremely small. However, we know that in thin layers of such polymers, conditions can be realized for which high conductivity arises in them [1]. Furthermore, study of charge carrier transport in such systems has shown [2] the presence of two types of intrinsic charge carriers with close mobilities and concentrations. We also 50 0040-5760/09/4501-0050

Achievements in polycondensation and condensation polymers

“…It was found that the chem ical structures of (co)polymers influence their mor phology, thermal stability, and luminescent and optical properties [125][126][127][128][129][130][131][132][133][134][135][136][137][138][139][140].…”

NMR study of phthalide‐type poly(phenylene)s. Symmetry and additivity

“…Currently, there are various kinds of bridged polyphenyl materials, including poly(arylenphthalides) that contain solubilizing phthalide groups, for light‐emitting and other optoelectronic devices . Their properties can be controlled by changing the structure of the bridged phenyl fragments . Homo‐poly(arylenphthalide), containing diphenyl, diphenyl oxide, diphenyl sulfide and fluorene fragments, as well as regularly alternating and sequentially ordered poly(arylenphthalide) periodic structures with terphenyl and diphenyl oxide fragments in the main chain were studied earlier with NMR techniques.…”

Stereospecific effects in the radical polymerization of 3-methylidene phthalide

“…13 Specific features of polymerization of cyclic compounds bearing the exocyclic double bond were reviewed. 14 Unique electrophysical properties (electrolumines cence, electric current switching over under the action of ex ternal effects, and electrical conductivity of thin films 15, 16 ) were found in poly(diphenylene phthalide) synthesized by polycondensation, which resulted in enhanced interest in cardopolymers containing the phthalide substituent. This work is devoted to one of such polymers: poly 3 methyl idene phthalide (PMP) in which the phthalide cycles are separated by methylene bridges.…”