Quantum Dot-Polyfluorene Composites for White-Light-Emitting Quantum Dot-Based LEDs.

Mariya Zvaigzne,Dmitriy Il’Gach,Pavel Samokhvalov,Alexander Yakimansky,Igor Nabiev,Irina Domanina

doi:10.3390/nano10122487

Abstract

Colloidal quantum dots (QDs) are a promising luminescent material for the development of next generation hybrid light-emitting diodes (QDLEDs). In particular, QDs are of great interest in terms of the development of solid-state light sources with an emission spectrum that mimics daylight. In this study, we used CdSe(core)/ZnS/CdS/ZnS(shell) QDs with organic ligands mimicking polyfluorene and its modified derivatives to obtain QD–polymer composites emitting white light. We found that the emission of the composites obtained by spin-coating, being strongly dependent on the chemical structure of the polymer matrix and the QD-to-polymer mass ratio, can be accurately controlled and adjusted to bring its emission spectrum close to the spectrum of daylight (CIE coordinates: 1931 0.307; 0.376). Moreover, the light emission of these composites has been found to be temporally stable, which is due to the minimal structural instability and volume-uniform charge and energy transfer properties. Thus, the use of the synthesized polyfluorene-based organic ligands with controllable chemical structures adaptable to the structure of the polymer matrix can significantly increase the stability of white light emission from QD composites, which can be considered promising electroluminescent materials for fabrication of white QDLEDs.

Highlights

Colloidal quantum dots (QDs) are luminescent nanocrystals that have great potential for use in many applications
We systematically investigated the optical properties of QD–polymer composites and developed composites based on CdSe(core)/ZnS/CdS/ZnS(shell) QDs and polyfluorene-based ligands emitting white light
We found that all of the studied polymers can be used to fabricate QD–polymer composites with a white emission spectrum, their temporal stability and predictability of the spectral coordinates strongly depend on the exact mass ratio between the QDs and polymer matrix and on the type of organic ligands used for the QD stabilization

Summary

Introduction

Colloidal quantum dots (QDs) are luminescent nanocrystals that have great potential for use in many applications Their unique physical and chemical properties determine a variety of new QD-based trends in biomedicine, laser physics, and optoelectronics [1,2,3,4,5]. The major advantage of QDs is the possibility to control their optical properties, i.e., the luminescence maximum wavelength and absorption spectral range, by varying their physical size. Another important particularity of QD properties is the possibility of obtaining colloidal solutions of QDs that can be used as fluorescent inks, which makes it possible to fabricate functional QD films using relatively cheap methods, such as spin-coating or applying QDs by inkjet printing [6,7,8]. QDs are of particular interest in the development of solid-state light sources with an emission spectrum that mimics daylight

Methods

Results

Conclusion