High Mobility in Nanocrystal-Based Transparent Conducting Oxide Thin Films

Abstract

Charge carrier mobility in transparent conducting oxide (TCO) films is mainly limited by impurity scattering, grain boundary scattering, and a hopping transport mechanism. We enhanced the mobility in nanocrystal (NC)-based TCO films, exceeding even typical values found in sputtered thin films, by addressing each of these scattering factors. Impurity scattering is diminished by incorporating cerium as a dopant in indium oxide NCs instead of the more typical dopant, tin. Grain boundary scattering is reduced by using large NCs with a size of 21 nm, which nonetheless were sufficiently small to avoid haze due to light scattering. In-filling of the precursor solution followed by annealing results in a NC-based composite film which conducts electrons through metal-like transport at room temperature, readily distinguished by the positive temperature coefficient of resistance. Cerium-doped indium oxide (Ce:InO) NC-based composite films achieve a high mobility of 56.0 cm/V·s, and a low resistivity of 1.25 × 10 Ω·cm. The films are transparent to a broad range of visible and near-infrared light from 400 nm to at least 2500 nm wavelength. On the basis of the high conductivity and high transparency of the Ce:InO NC-based composite films, the films are successfully applied as transparent electrodes within an electrochromic device.

Radio-frequency and optically transparent radome de-icing materials: fluorine-doped tin oxide

“…In TCO thin lms including FTO, the Hall mobility is usually limited by two major scattering mechanisms: grain boundary scattering and ionized impurity scattering. 21,22 The main scattering mechanism can be deduced from a comparison between the mean free path and the grain size. When the mean free path of free carriers is comparable to the grain size in the lms, grain boundary scattering is the dominant scattering.…”

“…When the mean free path is considerably shorter than the grain size of the lms, the Hall mobility is limited by the ionized impurity scattering rather than the grain boundary scattering. The mean free path l is calculated according to the following equation: 21,23 l…”

Ethanolamine-assisted low-temperature crystallization of hydroxide nanoparticle ink into transparent and conductive ITO layers

“…The use of the dispersing agent creates unwanted gaps between NCs, which impede the electron transport and decrease electrical conductivity. In recent work by Kim et al, 14 the gaps between adjacent nanoparticles were lled with precursors composed of nitrate, and the improvement of carrier mobility in the case of Ce-doped ITO layers was observed. However, the postdeposition annealing temperature was as high as 500 C.…”

Ultrasonic Spray Pyrolysis of Antimony‐Doped Tin Oxide Transparent Conductive Coatings

“…[8,9] Although excellent results have been recently achieved for ITO films deposited via solution-based methods, therefore avoiding the use of costly vacuum depositions, the presence of indium still poses serious concerns for the future widespread development of many optoelectronic devices. [10][11][12] Tin dioxide, and especially fluorine-doped tin oxide (FTO) is another competitor for the TCO market, due to its excellent optoelectronic properties (band gap energy ≈ 3.6 eV, electrical conductivity greater than 10 3 S cm −1 ), great chemical and temperature resistance, and use of more abundant and less expensive materials. [13] In addition, its compatibility with the float glass manufacturing process makes it rather inexpensive to produce.…”