Electronic Two-Transition-Induced Enhancement of Emission Efficiency in Polymer Light-Emitting Diodes.

Ren-Ai Chen,Sheng Li,Thomas George,Cong Wang

doi:10.3390/ma6030886

Abstract

With the development of experimental techniques, effective injection and transportation of electrons is proven as a way to obtain polymer light-emitting diodes (PLEDs) with high quantum efficiency. This paper reveals a valid mechanism for the enhancement of quantum efficiency in PLEDs. When an external electric field is applied, the interaction between a negative polaron and triplet exciton leads to an electronic two-transition process, which induces the exciton to emit light and thus improve the emission efficiency of PLEDs.

Highlights

Because of the potential advantagesof organic light-emitting diodes (OLEDs) or polymer light-emitting diodes (PLEDs) as optoelectronic devices [1,2,3], they have become “hot” research topics during the last several decades
PLEDs/OLEDs is limited to 25%, which is due to the ratio of the radiative singlet exciton to the non-radiative triplet exciton being 1:3
In order to improve the quantum efficiency, a hole injection layer (HIL) and electron injection layer (EIL) are embedded in the the poor transport of an electron injection layer leads to an imbalance between the hole and electron currents, lowering the device performance

Summary

Introduction

Of organic light-emitting diodes (OLEDs) or polymer light-emitting diodes (PLEDs) as optoelectronic devices [1,2,3], they have become “hot” research topics during the last several decades. The simplest structure of OLEDs/PLEDs is, generally, like a sandwich—an emitting layer between an anode and cathode. In order to improve the quantum efficiency, a hole injection layer (HIL) and electron injection layer (EIL) are embedded in the OLEDs/PLEDs. the poor transport of an electron injection layer leads to an imbalance between the hole and electron currents, lowering the device performance. As low-work-function metal cathodes for electron injection, such as Li, Ca and Mg, are not stable in air, it becomes necessary to rigorously encapsulate the devices. Emissive polymeric materials tend to be based on hole injection and transport [4,5,6]

Methods

Results

Conclusion