Highly Efficient Polymer Light-Emitting Diodes Using Graphene Oxide as a Hole Transport Layer

Abstract

We present an investigation of polymer light-emitting diodes (PLEDs) with a solution-processable graphene oxide (GO) interlayer. The GO layer with a wide band gap blocks electron transport from an emissive polymer to an ITO anode while reducing the exciton quenching between the GO and the active layer in place of poly(styrenesulfonate)-doped poly(3,4-ethylenedioxythiophene) (PEDOT:PSS). This GO interlayer maximizes hole-electron recombinations within the emissive layer, finally enhancing device performance and efficiency levels in PLEDs. It was found that the thickness of the GO layer is an important factor in device performance. PLEDs with a 4.3 nm thick GO interlayer are superior to both those with PEDOT:PSS layers as well as those with rGO, showing maximum luminance of 39 000 Cd/m(2), maximum luminous efficiencies of 19.1 Cd/A (at 6.8 V), and maximum power efficiency as high as 11.0 lm/W (at 4.4 V). This indicates that PLEDs with a GO layer show a 220% increase in their luminous efficiency and 280% increase in their power conversion efficiency compared to PLEDs with PEDOT:PSS.

Highly Efficient Inverted Organic Solar Cells Through Material and Interfacial Engineering of Indacenodithieno[3,2‐b]thiophene‐Based Polymers and Devices

“…However, a thin GO fi lm did not bring the signifi cant enhancement of the results due to its limited electron-blocking ability. [ 35 ] To further improve the anode contact, a hybrid bilayer interfacial material based on GO/MoO 3 was developed. Interestingly, there is a synergistic effect in BHJ solar cells when the GO and MoO 3 are sequentially spin-coated and deposited on top of the BHJ.…”

Improved efficiency of indium-tin-oxide-free organic light-emitting devices using PEDOT:PSS/graphene oxide composite anode

“…The functional groups, in this case the epoxy and hydroxyl groups, disrupt the sp 2 conjugation of the hexagonal graphene lattice in the basal plane. Thus, GO behaves as an insulator with a large band gap of around 3.6 eV [20,21,26,27]. This implies that the ratio of GO in PEDOT:PSS-GO composite anode should not be heavy, for avoiding excessive GO leading to low conductivity of the anode.…”

“…For this purpose, a thin film of graphene oxide (GO) was recently reported as an efficient hole transport layer for high-performance OLEDs and organic photovoltaic devices (OPVs) [20,21]. However, the cell performance is highly sensitive to the film thickness of the GO due to its insulating property.…”

Enhanced polymer light-emitting diode property using fluorescent conducting polymer-reduced graphene oxide nanocomposite as active emissive layer

“…Recent reports also indicate that replacing conventional transparent electrode (ITO) and hole transporting layer (PEDOT:PSS) with Fig. 1 Comparative Raman spectra of reduced graphene oxides obtained at different oxidation-reduction stages (rGO2 and rGO1) using 320 nm laser large band gap (*3.6 eV) negatively charged GO (behaves like an insulator) maximizes hole-electron recombination within emissive layer, enhancing PLEDS device performance and efficiency Han et al 2012;Lee et al 2012;Zhong et al 2011).…”

“…Graphene Graphene by CVD technique Flexible LED using graphene in place of transparent ITO anode Han et al (2012) 2. Graphene oxide (GO) and reduced graphene oxide (rGO) GO and rGO by chemical route GO and rGO in place of hole injecting layer Lee et al (2012) 3. Reduced graphene oxide Thermally reduced graphene oxide PEDOT:PSS/Graphene Nanocomposite as hole injecting layer Lin et al (2012) 4.…”