Electroluminescence and optical properties of poly(phenylenevinylene)/J-aggregate composites

Abstract A composite material of poly(phenylenevinylene) (PPV) doped by dye aggregates was prepared. A very efficient and temperature activated energy transfer (ET) from the PPV to the dye aggregates was attributed to F . orster ET accompanied by exciton diffusion. A clear complementary relation between the photoluminescence (PL) and electroluminscence (EL) images was observed for thin (15 nm) PPV-based OLEDs. So-called ''black spots'' in EL become bright ones when the photoluminescence of the same area was excited. This effect was attributed to the presence of an insulating layer between the polymer and aluminium.

Degradation of organic light-emitting diodes based on different-ligand complexes of terbium (III) salicylate and 2-phenoxybenzoate

International audienceDegradation (D) of organic light-emitting diodes (OLEDs) based on new different-ligand complexes of terbium salicylate (Tb(Sal)3(TPPO)2) and 2-phenoxybenzoate (Tb(pobz)3(TPPO)2) with triphenyl phosphinoxide (TPPO) was studied. Initial reversible D is associated with charge carrier trap filling. A temperature increase, applied stress relief, and short-term irradiation with UV light lead to trapped charge carrier release and electroluminescence (EL) intensity recovery. During strong heating, irreversible D is observed after the recovery; this D requires in addition an electric field (EF). Intense UV light causes D without EF. The use of ac bias voltage eliminates reversible D, and sealing retards irreversible long-term D

Photo- and electroluminescent properties of zinc(II) complexes with tetradentate Schiff bases, derivatives of salicylic aldehyde

International audienceIt is studied how the introduction of various substituents into the composition of organic ligands affects the photoluminescence spectra of new zinc(II) complexes with tetradentate Schiff bases H2L (derivatives of salicylic aldehyde (H2SAL1, H2SAL2) and o-vanillin (H2MO1, H2MO2) with ethylenediamine and o-phenylenediamine) in the form of bulk solids and thin films. It is demonstrated that the emission spectra of bulk solid complexes without o-phenylenediamine bridges (ZnSAL1 and ZnMO1) contain additional long-wavelength bands compared to the spectra of corresponding thin films. In the case of films obtained from [ZnSAL1]2 dimer complexes, the long-wavelength band is dominant. At the same time, the photoluminescence spectra of ZnSAL2 and ZnMO2 complexes with o-phenylenediamine bridges are similar in the case of solid samples and thin films. The electroluminescent properties of organic light-emitting diodes (OLEDs) with the ITO/α-NPD/ZnL/Ca:Al structure are studied. The bathochromic shift of the electroluminescence peaks of OLEDs with respect to the photoluminescence spectra of bulk solid samples and thin films is probably related to the formation of exciplexes at the α-NPD/ZnL interface. The electroluminescence spectra of OLEDs based on [ZnSAL1]2 show a hypsochromic shift of the emission maximum, which can be caused by a shift of the recombination region into the α-NPD layer

OLED thin film fabrication from poorly soluble terbium o-phenoxybenzoate through soluble mixed-ligand complexes

Features and advantages of the approach of the luminescent thin film deposition of non-volatile and non-soluble lanthanide aromatic carboxylates were exemplified by thin film deposition of terbium o-phenoxybenzoate Tb(pobz)3(H2O)2 (I) with quantum yield measured to be 96%. This approach is based on the formation and decomposition of mixed-ligand complexes, and thus mixed-ligand complex Tb(pobz)3(MG)(H2O)2 (II) (MG - monoglyme) was synthesized, characterized and used as a precursor for I thin films. Electroluminescent (EL) properties of high quality thin films of I and those with suitable host material were studied in a series of OLED devices