High luminescent efficiency in light-emitting polymers due to effective exciton confinement

Abstract

Highly efficient light-emitting polymers have become possible by molecular engineering. Photoluminescence (PL) quantum yield above 90% in the solid state is reported for the alternating block copolymer of distyrylbenzene. We conclude that the alternate arrangement of conjugated and nonconjugated segments with surrounding side groups for chromophores effectively confine the excitons for radiative emission. The effectiveness of the exciton confinement is confirmed through the temperature independence of the PL quantum yield. The time-resolved PL decay measurement supports this model through the independence of the PL yield on temperature and emission wavelength. The synthesized copolymers have been employed for the fabrication of electroluminescent (EL) devices, demonstrating high external EL efficiency with low operation threshold.

Quantum Confinement and Crystalline Structure of CdSe Nanocrystalline Films

“…Semiconductor quantum dots play an important role in nanostructure physics and have great potential for valuable technical applications [1,2]. Quantum confinement phenomenon in CdSe is one of the most studied subjects due to the good characteristics of this material for the understanding of the physical properties of nanometer size structures [1].…”

Electro-optical interfacial effects on a graphene/π-conjugated organic semiconductor hybrid system

“…Since molecular packing and ordering influence optical properties of organic semiconductors [7–13], it is important to investigate whether the graphene-induced ordering affected the optical properties of this novel RA SAM structure. Therefore, photoluminescence (PL) studies of RA monolayers and multilayers atop graphite microplates were performed as a function of temperature (Fig.…”

“…Their optical and electronic properties are strongly linked to intermolecular interaction parameters associated with molecular packing and/or ordering [7]. Previous works have demonstrated that intermolecular interactions can dramatically reduce the luminescence quantum yield in solid-state devices [8–13]. In this context, it is important to control the ordering of π-conjugated organic molecules to make their use on optoelectronic devices possible.…”

Bright Light Emission of a Single Polythiophene Nanotube Strand with a Nanometer‐scale Metal Coating

“…The photoluminescence (PL) efficiency of p-conjugated organic molecules and polymer materials can be enhanced by an increase in singlet excitons, a morphological improvement with reduction of trap sites, the confinement effect of excitons, etc. [1][2][3] A triplet-state emission can occur in the light-emitting organic materials with a phosphorescence sensitizer. [4,5] For the fabrication of more efficient OLEDs, the mobility of an electron and a hole should be balanced, because the electron mobility of p-conjugated polymers is 10 2 to 10 3 times lower than the hole mobility.…”