A Facile Solution-Phase Approach to Transparent and Conducting ITO Nanocrystal Assemblies

Abstract

Monodisperse 11 nm indium tin oxide (ITO) nanocrystals (NCs) were synthesized by thermal decomposition of indium acetylacetonate, In(acac)(3), and tin bis(acetylacetonate)dichloride, Sn(acac)(2)Cl(2), at 270 °C in 1-octadecene with oleylamine and oleic acid as surfactants. Dispersed in hexane, these ITO NCs were spin-cast on centimeter-wide glass substrates, forming uniform ITO NC assemblies with root-mean-square roughness of 2.9 nm. The assembly thickness was controlled by ITO NC concentrations in hexane and rotation speeds of the spin coater. Via controlled thermal annealing at 300 °C for 6 h under Ar and 5% H(2), the ITO NC assemblies became conductive and transparent with the 146 nm-thick assembly showing 5.2 × 10(-3) Ω·cm (R(s) = 356 Ω/sq) resistivity and 93% transparency in the visible spectral range--the best values ever reported for ITO NC assemblies prepared from solution phase processes. The stable hexane dispersion of ITO NCs was also readily spin-cast on polyimide (T(g) ~360 °C), and the resultant ITO assembly exhibited a comparable conductivity and transparency to the assembly on a glass substrate. The reported synthesis and assembly provide a promising solution to the fabrication of transparent and conducting ITO NCs on flexible substrates for optoelectronic applications.

Shape Controlled Plasmonic Sn Doped CdO Colloidal Nanocrystals: A Synthetic Route to Maximize the Figure of Merit of Transparent Conducting Oxide

“…Resistivity (ρ), Hall mobility (µ), carrier density (N), thickness of films (t), FOM (T/R s ) of different NCs assembly (the best one from each set) are summarized in Table 1. The FOM values of all the best conducting films are of the order of 10 −1 Ω −1 much higher than previous reported solution processed ITO thin film [53] and Sn doped Zn-Cd-O system. [19] The obtained FOM value meets the industrial criteria for transparent electrode in LCD pixels and touch panels.…”

Synthesis of N-Type Plasmonic Oxide Nanocrystals and the Optical and Electrical Characterization of their Transparent Conducting Films

“…ITO samples showed similar, lower resistivity at doping >5%, due to mobilities 10−100 times smaller (∼0.01 cm 2 V −1 s −1 ) than those with a CdO host (∼1 cm 2 V −1 s −1 ) or previous reports of ITO NCs annealed under reducing conditions. 11 Oxidative annealing conditions eliminate oxygen vacancies and lower the free electron concentration in ITO thin films to the order of 10 19 cm −3 , below the expected values based on the colloidal solution-phase LSPR feature but with the average slightly increasing with dopant concentration determined by elemental analysis. The average estimated carrier density in ICO also increased slightly with doping concentration.…”

Effect of ambient combinations of argon, oxygen, and hydrogen on the properties of DC magnetron sputtered indium tin oxide films

“…7 The electrical, optical, infrared reflectance, hardness and chemical stability material properties of ITO are well characterized. [8][9][10] ITO can be fabricated by DC and RF magnetron sputtering, 1,5 electron beam evaporation, 9 thermal evaporation, 11 spray pyrolysis, 12 chemical solution deposition, 13 and the sol gel method. 14 Among the various methods, magnetron sputtering is most often used by industry to fabricate commercial optoelectronic devices.…”