Enhancement of optoelectronic properties and stability in organic luminescent material for polymer light emitting diodes PLEDs

Abstract

Polymer Light Emitting Diodes (PLEDs) have drawn a huge attention towards the development of low-cost Solid-State Lighting (SSL) devices and flat panel displays, mainly due to their unique advantages including flexibility, large-area scalability and wet processing technology. The performance and lifetime of PLEDs rely on the properties of organic luminescent materials, device architecture and fabrication technology. Though it has been more than three decades, PLEDs lack commercialization because of complex processability, poor environmental stability and low quantum efficiency. Hence this research is focused on developing a heterostructure organic luminescent material for PLED displays with improved efficiency, photostability and color tuning ability. newlineThe objective of this work is to improve the optoelectronic properties and photostability of the Light Emitting Polymer (LEP), poly[2-methoxy-5-(2 -ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). MEH-PPV is an emissive polymer prominently used in PLEDs. It exhibits higher hole mobility and it is unstable in an ambient environment. This leads to electron trapping which has an intense impact on the optoelectronic device characteristics. The presence of traps can alter energy levels and charge transport in LEPs causing non-radiative Shockley-Read-Hall (SRH) recombination which decreases the quantum efficiency and lifetime. A direct way to eliminate trap is purification, which is not 100% successful till date. Alternatively, the traps can be filled or diluted. newline newline newline