Improved Internal Quantum Efficiency and Light-Extraction Efficiency of Organic Light-Emitting Diodes via Synergistic Doping with Au and Ag Nanoparticles

Changsoon Cho; Hyunbum Kang; Se-Woong Baek; Taesu Kim; Changyeon Lee; Bumjoon J Kim; Jung-Yong Lee

doi:10.1021/acsami.6b07666

Improved Internal Quantum Efficiency and Light-Extraction Efficiency of Organic Light-Emitting Diodes via Synergistic Doping with Au and Ag Nanoparticles

ACS Appl Mater Interfaces. 2016 Oct 19;8(41):27911-27919. doi: 10.1021/acsami.6b07666. Epub 2016 Oct 5.

Authors

Changsoon Cho¹, Hyunbum Kang¹, Se-Woong Baek¹, Taesu Kim¹, Changyeon Lee¹, Bumjoon J Kim¹, Jung-Yong Lee¹

Affiliation

¹ Graduate School of Energy, Environment, Water, and Sustainability (EEWS) and ‡Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea.

PMID: 27669058
DOI: 10.1021/acsami.6b07666

Abstract

This paper reports the distinct roles of Au and Ag nanoparticles (NPs) in organic light-emitting diodes (OLEDs) depending on their sizes. Au and Ag NPs that are 40 and 50 nm in size, respectively, are the most effective for enhancing the performance of green OLEDs. The external quantum efficiencies (EQEs) of green OLEDs doped with Au and Ag NPs (40 and 50 nm, respectively) are improved by 29.5% and 36.1%, respectively, while the power efficiencies (PEs) are enhanced by 47.9% and 37.5%, respectively. Furthermore, combining the Au and Ag NPs produces greater enhancements. The EQE and PE of the codoped OLEDs are improved by 63.9% and 68.8%, respectively, through the synergistic behavior of the different NPs. Finite-difference time-domain simulations confirm that the localized surface-plasmon resonance of the Au NPs near 580 nm improves the radiative recombination rate (k_rad) of green-light emitters locally (<50 nm), while the Ag NPs cause relatively long-range and broadband enhancements in k_rad. The simulations of various domain sizes verify that the light-extraction efficiency (LEE) can be enhanced by more than 4.2% by applying Ag NPs. Thus, size-controlled Au and Ag NPs can synergistically enhance OLEDs by improving both the internal quantum efficiency and LEE.

Keywords: dual metal nanoparticles; internal quantum efficiency; light-extraction efficiency; organic light-emitting diodes; size-controlled metal nanoparticles.