ZnO Nanorod Arrays as Electron Injection Layers for Efficient Organic Light Emitting Diodes

Faria, Jorge C. D.; Campbell, Alasdair J.; McLachlan, Martyn A.

doi:10.1002/adfm.201501411

Cited by 26 publications

(23 citation statements)

References 54 publications

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“…13 Indeed one or all of these defect species may contribute to the enhanced conductivity of ZnO post anneal. 31 further highlighting the applicability of these materials beyond TCO applications.…”

Section: Introductionmentioning

confidence: 99%

Probing the doping mechanisms and electrical properties of Al, Ga and In doped ZnO prepared by spray pyrolysis

et al. 2016

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© 2016 The Royal Society of Chemistry.The measured structural, optical and electrical properties of Al, Ga and In doped ZnO films deposited using spray pyrolysis are reported over the doping range 0.1-3 at%. Over the entire doping series highly transparent, polycrystalline thin films are prepared. Using AC Hall as a measurement technique we probe the electronic properties of our doped films, deconvoluting the impact of doping on the measured charge carrier concentrations and Hall mobility. We focus on the low doping range i.e. 0.1-1 at%, where we observe unexpected variations in charge carrier concentration and mobility and propose a mechanism to explain our observations. In this doping range highly resistive films are formed hence we highlight AC Hall as a reliable and highly reproducible technique for analysing electrical properties and subsequently elucidate the doping mechanisms. The implementation of a simple, post-deposition heat treatment demonstrated on our AZO results in typical films with charge carrier concentrations exceeding >1019 cm-3, and electron mobilities >10 cm2 V-1 s-1 and stability exceeding 180 days. We describe in detail the nature of the defect chemistry and the role of intrinsic defects and show, that despite significant variations in dopant species and grain boundary concentrations, that the defect chemistry dominates the electrical characteristics

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Section: Introductionmentioning

confidence: 99%

Probing the doping mechanisms and electrical properties of Al, Ga and In doped ZnO prepared by spray pyrolysis

et al. 2016

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“…Fluorene-triarylamine copolymers are specifi cally designed to be amorphous, with high glass transition temperatures, for use as interlayer and hole transport layer materials in polymer light emitting diodes. [31][32][33][34][35][36][37] They have also been used, along with the homopolymer poly(triarylamine), as p-type semiconductors in OFETs, allowing highly uniform charge transport over large-area substrates, an important requirement for applications such as display backplanes. [ 38 ] Their charge transport has been extensively studied in bulk diodes using the time-of-fl ight (TOF) and transient SCLC dark injection (DI) techniques, [39][40][41][42] and modeled in the low chargecarrier density regime using the GDM, correlated GDM, and polaronic correlated GDM.…”

Section: Introductionmentioning

confidence: 99%

Charge‐Carrier Density Independent Mobility in Amorphous Fluorene‐Triarylamine Copolymers

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et al. 2016

Adv Funct Materials

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3720 wileyonlinelibrary.com (OPVs), and organic fi eld-effect transistors (OFETs). A crucial parameter in the development of these technologies is the OSC charge-carrier mobility, and how it is related to the different OSC materials, processing, device architectures, and device operating conditions. Many semiconducting polymers and small molecules are amorphous, and such disorder in the physical morphology is expected to refl ect itself in disorder of the energy levels of the hole and electron transport states ( Figure 1 a). Such energetic disorder will directly impact charge transport and mobility. [1][2][3][4][5][6][7][8][9][10][11][12] For such energetically disordered OSCs, one feature predicted by many charge transport models is a charge-carrier density dependent mobility. The original Gaussian disorder model (GDM) developed by Bässler for hopping transport in a Gaussian density of states (DOS) distribution was a single carrier approach, [ 1 ] as were the models based on it which considered both correlated energetic disorder, [ 2 ] with a smoothly varying energy landscape (see Figure 1 a), and the effect of polaronic relaxation. [ 3 ] The percolation model developed by Vissenberg and Matters for transport involving an exponential DOS instead considered multiple carriers, [ 4 ] and this predicted a mobility which has a power-law dependency on the charge-carrier density. The measured transistor mobility falls two to three orders of magnitude below that predicted from the charge-carrier density dependent model, and does not follow the expected power-law relationship. The experimental results for these two amorphous polymers are therefore consistent with a charge-carrier density independent mobility, and this is discussed in terms of polaron-dominated hopping and interchain correlated disorder.

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“…The architecture of inverted light-emitting devices is constructed with the configuration of cathode/ETL/active layer/HTL/metal anode [3, 4]. Many n -type metal oxide materials, including zinc oxide (ZnO), titanium dioxide (TiO 2 ), and tin dioxide have been used as ETL [5–7]. On the other hand, p -type materials such as vanadium oxide, nickel oxide, and tungsten trioxide (WO 3 ) can be utilized as HTL [8–10].…”

Section: Introductionmentioning

confidence: 99%

Solution-Processed Hybrid Light-Emitting Devices Comprising TiO2 Nanorods and WO3 Layers as Carrier-Transporting Layers

2016

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The goal of this research is to prepare inverted light-emitting devices with improved performance by combining titanium dioxide (TiO2) nanorods and tungsten trioxide (WO3) layer. TiO2 nanorods with different lengths were established directly on the fluorine-doped tin oxide (FTO) substrates by the hydrothermal method. The prepared TiO2 nanorods with lengths shorter than 200 nm possess transmittance higher than 80% in the visible range. Inverted light-emitting devices with the configuration of FTO/TiO2 nanorods/ionic PF/MEH-PPV/PEDOT:PSS/WO3/Au were constructed. The best device based on 100-nm-height TiO2 nanorods achieved a max brightness of 4493 cd/m2 and current efficiency of 0.66 cd/A, revealing much higher performance compared with those using TiO2 compact layer or nanorods with longer lengths as electron-transporting layers.

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ZnO Nanorod Arrays as Electron Injection Layers for Efficient Organic Light Emitting Diodes

Cited by 26 publications

References 54 publications

Probing the doping mechanisms and electrical properties of Al, Ga and In doped ZnO prepared by spray pyrolysis

Probing the doping mechanisms and electrical properties of Al, Ga and In doped ZnO prepared by spray pyrolysis

Charge‐Carrier Density Independent Mobility in Amorphous Fluorene‐Triarylamine Copolymers

Solution-Processed Hybrid Light-Emitting Devices Comprising TiO2 Nanorods and WO3 Layers as Carrier-Transporting Layers

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