The application of single-layer graphene modified with solution-processed TiOx and PEDOT:PSS as a transparent conductive anode in organic light-emitting diodes

• Published in: Organic electronics Vol. 14; no. 12; pp. 3348 - 3354
• Main Authors: Zhu, Xiao-Zhao, Han, Yuan-Yuan, Liu, Yuan, Ruan, Kai-Qun, Xu, Mei-Feng, Wang, Zhao-Kui, Jie, Jian-Sheng, Liao, Liang-Sheng
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.12.2013; Elsevier
• Subjects: Applied sciences; Circuit properties; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electric, optical and optoelectronic circuits; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronics; Exact sciences and technology; Graphene; Hydrophobic surface; Integrated optoelectronics. Optoelectronic circuits; OLED; Optical and optoelectronic circuits; Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Optoelectronic devices; PEDOT:PSS; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Surface double layers, schottky barriers, and work functions; TiOx; Work function; TiOx; OLED; Work function; Graphene; PEDOT:PSS; Hydrophobic surface; Interfacial layer; Performance evaluation; Interlayers; Conducting material; Anode; Doping; Methyl methacrylate polymer; Coverage rate; Tin addition; Sheet resistivity; Thiophene derivative polymer; Optoelectronic device; Titanium; TiO; Growth from solution; Organic electronics; Optoelectronics; Polymer blends; Doped materials; Absorption coefficient; Transmittance; Indium oxide; Transfer processing; Short circuit; Flexible structure; Residual impurity; Styrenesulfonic acid polymer; Organic light emitting diodes; Styrenesulfonate polymer; Zero band gap semiconductors; Titanium oxide; Transparent material
• ISSN: 1566-1199; 1878-5530
• DOI: 10.1016/j.orgel.2013.10.003

[Display omitted] •A single layer graphene was modified with TiOx and PEDOT:PSS.•The sheet resistance of the modified graphene was reduced by 86% from 628Ω/sq to 86Ω/sq.•The work function of the modified graphene was increased by 0.82eV from 4.30eV to 5.12eV.•Enhanced charge injection and transport were achieved from the modified graphene. There are many challenges for a direct application of graphene as the electrodes in organic electronics due to its hydrophobic surfaces, low work function (WF) and poor conductance. The authors demonstrate a modified single-layer graphene (SLG) as the anode in organic light-emitting diodes (OLEDs). The SLG, doped with the solution-processed titanium suboxide (TiOx) and poly(3,4-ethylenedio-xythiophene)/poly(styrene sulfonic acid) (PEDOT:PSS), exhibits excellent optoelectronic characteristics with reduced sheet resistance (Rsq), increased work function, as well as over 92% transmittance in the visible region. It is notable that the Rsq of graphene decreased by ∼86% from 628Ω/sq to 86Ω/sq and the WF of graphene increased about 0.82eV from 4.30eV to 5.12eV after a modification by using the TiOx–PEDOT:PSS double interlayers. In addition, the existence of additional TiOx and PEDOT:PSS layers offers a good coverage to the PMMA residuals on SLG, which are often introduced during graphene transfer processes. As a result, the electrical shorting due to the PMMA residues in the device can be effectively suppressed. By using the modified SLG as a bottom anode in OLEDs, the device exhibited comparable current efficiency and power efficiency to those of the ITO based reference OLEDs. The approach demonstrated in this work could potentially provide a viable way to fabricate highly efficient and flexible OLEDs based on graphene anode.