Promising Hybrid Graphene-Silver Nanowire Composite Electrode for Flexible Organic Light-Emitting Diodes

Abstract

Thanks to its high transparency, high carrier mobility, and thermal conductivity, graphene is often used as transparent conductive electrode (TCE) in optoelectronic devices. However, the low carrier concentration and high resistance caused by vacancy defects, grain boundaries, and superposed folds in typical graphene films limit its application. In this study, we propose a method to increase both the conductivity and carrier concentration in single-layer graphene (SLG) by blending it with silver nanowires (AgNWs). AgNWs provide connections between grain boundaries of graphene to improve charge-carrier transport. The AgNWs in this study can reduce the resistance of SLG from 650 Ω/◻ to 27 Ω/◻ yet still maintain a transmittance of 86.7% (at 550 nm). Flexible organic light-emitting diode, with a maximum 15000 cd m−2 luminance was successfully fabricated using such graphene and AgNWs composite transparent electrodes.

Flexible and Transparent Electrodes of Cu2−XSe with Charge Transport via Direct Tunneling Effect

“…Cu 2−X Se [48][49][50] Optical bandgap ≈ 2.3 eV Sheet resistance ≈ 148 Ω sq −1 Transmittance ≈ 50-60% σ RMS ≈ 11.3 nm Flexibility: yes Synthesis: Chemical Bath Deposition (CBD) Transparent conductive oxides: ITO, FTO, ZnO, InZnO, ZTO, TiO 2 , MoO [1,2,51] Optical bandgap ≈ 3.5 eV Sheet resistance ≈ 20-36 Ω sq −1 Transmittance ≈ 95% σ RMS ≈ 17.2 nm Flexibility: no Synthesis: radiofrequency (RF) sputtering Graphene [52] Optical bandgap ≈ 4. Transmittance ≈ 90% Flexibility: no (rigid glass substrate) Synthesis: DC pulsed (500 W) or RF (120 W) sputtering process on single-layer graphene on a Cu foil and subsequent wet-transfer process to a target substrate Graphene/Ag nanowire [57,58] Optical bandgap ≈ 4.9 eV Sheet resistance ≈ 26.4 Ω sq −1 Transmittance ≈ 91.5% σ RMS ≈ 6.4 nm Flexibility: no (rigid glass substrate) Synthesis: CVD Carbon Nanotubes (CNT) [59] Optical bandgap ≈ 4.1 eV Sheet resistance ≈ 100 Ω sq −1 Transmittance ≈ 90% Flexibility: no (rigid glass substrate) Synthesis: micro-contact printing CNT films with polydimethylsiloxane (PDMS) stamp Single-Wall Carbon Nanotube (SWNT) [60] Optical bandgap ≈ 4.7 eV Sheet resistance ≈ 60 Ω sq −1 Transmittance ≈ 45% Flexibility: no Synthesis: pulsed laser vaporization technique SWNT/PEDOT [61] Optical bandgap ≈ 1.6 eV Sheet resistance ≈ 160 Ω sq −1 Transmittance ≈ 86% Flexibility: yes Synthesis: in situ polymerization of PEDOT on poly(ethylene naftalina)/SWNT Polyethylene Terephthalate/ polyaniline:camphor sulfonic acid (PET/ PANI:CSA) [52] Optical bandgap ≈ 2.5 eV Transmittance > 70% Sheet resistance ≈ 100 Ω sq −1 Flexibility: yesSynthesis: spin-cast film of dissolved in m-cresol PANI:CSA on PET sheet…”

Transparent Supercapacitors: From Optical Theories to Optoelectronics Applications

“…Therefore, these Ag nanowire electrodes often need additional post‐treatment processes, which can improve conductivity of the resulting network electrode by heating, [ 173 ] pressing, [ 123 ] light sintering, [ 175 ] solvent washing, [ 176,177 ] and PEDOT:PSS (or graphene) welding. [ 178,179 ]…”

Solution-processed colored electrodes for ITO-free blue phosphorescent organic light-emitting diodes

“…Globally conducted experimental studies are oriented around organic light-emitting diodes (OLEDs) due to the interesting opportunities they offer for innovative display and lighting applications [1][2][3][4][5]. The progress towards the development and perfection of highly flexible and stretchable devices enhances the need for a new kind of material possessing the qualities of both highly conductive metal/oxide-based conductors and highly flexible plastics [6][7][8]. One of the essential elements of the light-emitting or harvesting optoelectronic devices, including OLEDs, touch screens, organic lightemitting transistors, and organic solar cells, is a material with high transparency along with high conductivity at least for one of the electrodes in the case of one-sided light emission or harvest [7][8][9][10].…”

“…The progress towards the development and perfection of highly flexible and stretchable devices enhances the need for a new kind of material possessing the qualities of both highly conductive metal/oxide-based conductors and highly flexible plastics [6][7][8]. One of the essential elements of the light-emitting or harvesting optoelectronic devices, including OLEDs, touch screens, organic lightemitting transistors, and organic solar cells, is a material with high transparency along with high conductivity at least for one of the electrodes in the case of one-sided light emission or harvest [7][8][9][10]. The most prominently applied transparent electrode material for the present-day devices is highly conductive tin-doped indium oxide (ITO) [3,[7][8][9][10][11].…”

“…One of the essential elements of the light-emitting or harvesting optoelectronic devices, including OLEDs, touch screens, organic lightemitting transistors, and organic solar cells, is a material with high transparency along with high conductivity at least for one of the electrodes in the case of one-sided light emission or harvest [7][8][9][10]. The most prominently applied transparent electrode material for the present-day devices is highly conductive tin-doped indium oxide (ITO) [3,[7][8][9][10][11]. Nevertheless, the increasing prices of ITO due to the decreasing availability of CONTACT Jonghee Lee jonghee.lee@hanbat.ac.kr; Jae-Hyun Lee jhyunlee@hanbat.ac.kr * These authors contributed equally to this work.…”