Formation of metallic indium-tin phase from indium-tin-oxide nanoparticles under reducing conditions and its influence on the electrical properties

Günther, Gerrit; Schierning, Gabi; Theissmann, Ralf; Kruk, Robert; Schmechel, Roland; Baehtz, Carsten; Prodi-Schwab, Anna

doi:10.1063/1.2958323

Cited by 37 publications

(43 citation statements)

References 55 publications

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“…In contrary to the results of Guenther et al [45] the maximum conductance of 65 V À1 cm À1 is achieved at a treatment temperature of 200 8C. The conductance enhancement comes along with a small rise in free charge carrier density from 2.6 to 3.6 Â 10 20 cm À3 , but a substantial improvement of the mobility from 0.15 to 1.1 cm 2 V À1 s À1 (see Fig.…”

Section: Temperature Treatment Under Reducing Conditionscontrasting

confidence: 54%

“…This applies to sol-gel layers [26,30,43] as well as nanoparticle dispersion derived thin films. [30,44,45] In the prevailing opinion the reason is an increase in free charge carrier density due to partial pressure gradient driven oxygen diffusion from regular lattice places out of the material generating oxygen vacancies and two free electrons per vacancy: [3,46,47] …”

Section: Temperature Treatment Under Reducing Conditionsmentioning

confidence: 99%

“…[48,49] Guenther et al even demonstrated reduction to the metallic indium-tin phase. [45] Annealing in vacuum for 30 min at a temperature of 550 8C leads to a conductance of 121 V À1 cm À1 accompanied by an electron density increase to 5.6 Â 10 20 cm À3 and a rise in mobility to 1.4 cm 2 V À1 s À1 (see Fig. 1 and Table 1).…”

Section: Temperature Treatment Under Reducing Conditionsmentioning

confidence: 99%

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Conductance Enhancement Mechanisms of Printable Nanoparticulate Indium Tin Oxide (ITO) Layers for Application in Organic Electronic Devices

et al. 2009

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Indium tin oxide (ITO, In 2 O 3 :SnO 2 ) thin films exhibit a high conductance along with brilliant transparency in the optical range. [1][2][3] In spite of the existence of some other transparent conducting oxide materials and the high material costs, ITO is widely used as transparent electrode material in stateof-the-art optoelectronic devices such as TFT-LCD-s, [4][5] plasma TV-s, and touchscreens. It is also utilized in novel, smart optoelectronic applications including organic solar cells, [6][7] electrochromic devices, [8] and organic light emitting diodes (OLEDs) for displays [9][10][11] or for lighting. [12] Usually ITO thin films are fabricated by physical vapor deposition (PVD) methods including RF-sputtering [13,14] and magnetron sputtering [2,[15][16][17] as well as pulsed laser deposition [18,19] and several other evaporation techniques. [20][21][22][23][24] PVD derived ITO layers are characterized by high conductances of partly more than 10 000 V À1 cm À1 , [19,22] but also by high production costs. Cost drivers are the inevitable vacuum process which hinders continuous production and the requirement of substractively wet chemical patterning steps. [4] Wet deposition techniques are of emerging interest due to their high cost reduction potential based on missing vacuum demand, printing possibility comprising large area fabrication potential, and the feasibility of direct patterning. Beside the several deposition methods, there exist two different principles of wet chemical processing: The sol-gel-technique, characterized by deposition of precursors with subsequent transformation into ITO [25][26][27][28][29][30] and the deposition of a dispersion containing ITO nanoparticles. [30][31][32][33][34] Sol-gel ITO films can possess adequate conductances of >350 V À1 cm À1 , [25,26,35] which can be increased to >1600 V À1 cm À1 by temperature treatment in nitrogen or forming gas. [26,30] Due to the required low precursor to solvent ratio, only thicknesses of about 10-20 nm can be achieved for the sol-gel single layers, [26,30] which leads to high sheet resistances. To avoid this, costly repetitions of the deposition and transformation sequence are necessary.In contrast to sol-gel ITO layers, nanoparticle dispersion derived thin films enable the production of almost every thickness. They can also be produced on flexible polymer substrates, [34] but exhibit comparatively low conductances. The latter is related to a poor electrical contact between the primary particle aggregates and high inter-grain porosity. [30,32,33] Typical conductance after layer deposition is in the order of 10 À2 V À1 cm À1 and rises to several 10 0 V À1 cm À1 after annealing in air at 550 8C. [33,36] In order to overcome this conductance bottleneck, we investigated the impact of various conductance improving techniques on the electrical, optical, and morphological properties of nanoparticulate printed ITO layers. ExperimentalNanoparticulate ITO layers for electrical measurements were made by spin-coating a commercial ethanolic dispersi...

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Section: Temperature Treatment Under Reducing Conditionscontrasting

confidence: 54%

Section: Temperature Treatment Under Reducing Conditionsmentioning

confidence: 99%

Section: Temperature Treatment Under Reducing Conditionsmentioning

confidence: 99%

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Conductance Enhancement Mechanisms of Printable Nanoparticulate Indium Tin Oxide (ITO) Layers for Application in Organic Electronic Devices

et al. 2009

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“…Related phenomena and their dependence on the properties of the grains are critically important for a broad spectrum of applications that involve solid-state electrolytes, sensing devices, and materials employed for printable electronics [39][40][41][42][43][44][45][46][47][48][49][50]. For TiO 2 , a prototype material for defect characterization studies on transition metal oxides, the bulk and surface defect structure depends on the degree of nonstoichiometry [51][52][53][54][55].…”

Section: Stoichiometry Levels Of Oxygen Deficiency and N-type Dopingmentioning

confidence: 99%

Defects in Metal Oxide Nanoparticle Powders

Berger

Diwald

2015

Defects at Oxide Surfaces

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Metal oxides are mainly used in powder or particulate form for their application as functional materials. Insights into functional as well as unwanted properties of different defect types ranging from oxygen vacancies to grain boundaries and pores require an integrated characterization approach and are extremely difficult to establish. After a brief introduction into the complexity of particle systems and related heterogeneities, we discuss examples where for defects and other distinct structural features of MgO or TiO 2 particle systems firm structureproperty relationships have been established. Moreover, we want to point out that processing of particle matters. Related microstructural changes can induce the formation of solid-solid interfaces upon transformation of nanoparticle powders into mesoporous nanoparticle networks. This change in aggregation level and microstructure can substantially modify the electronic, optical and spectroscopic properties of metal oxide nanoparticle ensembles and, for this reason, plays a critical role for the generation of structural and-at the same time-functional defects inside particle ensembles. Introduction Particle Systems and the Hierarchy of DefectsLarge quantities of metal oxide particle powders are widely used in materials science and employed in very diverse areas such as engineering [1] catalysis [2] electronics [3][4][5] and energy technology [6]. The behavior of a metal oxide powder

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“…ITO nanocrystals with low resistance have been obtained by annealing precursor firstly in air and then in N 2 /H 2 [23,24]. Although the presence of hydrogen is beneficial to increase the electrical conductivity of ITO nanocrystals, it will unavoidably introduce metal Sn/In impurities [25], and also bring about some risks because of its combustible property. Annealing in air and then in N 2 can achieve a high performance ITO film [26], and might avoid the formation of In/Sn metal impurities annealing in hydrogen atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Influence of post-annealing on the structure and optical properties of ITO nanocrystals prepared by electrochemical method

Xu¹,

Wang²,

Ding³

et al. 2012

Materials Research Bulletin

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Formation of metallic indium-tin phase from indium-tin-oxide nanoparticles under reducing conditions and its influence on the electrical properties

Cited by 37 publications

References 55 publications

Conductance Enhancement Mechanisms of Printable Nanoparticulate Indium Tin Oxide (ITO) Layers for Application in Organic Electronic Devices

Conductance Enhancement Mechanisms of Printable Nanoparticulate Indium Tin Oxide (ITO) Layers for Application in Organic Electronic Devices

Defects in Metal Oxide Nanoparticle Powders

Influence of post-annealing on the structure and optical properties of ITO nanocrystals prepared by electrochemical method

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