Aqueous Deposition of Ultraviolet Luminescent Columnar Tin‐Doped Indium Hydroxide Films

Abstract

Indium tin oxide (ITO) has attracted intense interest as the most important transparent conducting oxide (TCO) that sees wide use in many opto‐electronic and photo‐chemical devices. The goal of this study is to explore the possibility of depositing ITO thin films using a bioinspired aqueous deposition route as an alternative. On the surface of sulfonated‐self assembled monolayers, Sn‐doped indium hydroxide films are obtained via a hydrogen peroxide‐assisted method. As a result, the as‐deposited indium tin hydroxide films possess a single hexagonal phase of In(OH)3· xH2O (0 ≤ x ≤ 1) with Sn doping percentage of (1.7 ± 0.2) at % and a column‐like hierachical microstructure. Structural, compositional and property studies, including electron microscopy, X‐ray diffraction, photoelectron spectroscopy, optical transmittance, photoluminescence and four‐probe conductivity measurements, are conducted. The possible mechanism based on oriented attachment is discussed for the film growth. Strong room temperature photoluminescence within the near UV range is observed in the case of Sn‐doped, but not in the one of the pure In(OH)3· xH2O films. Annealing of the indium tin hydroxide films above 200 °C gives nanocrystalline Sn:In2O3 films with higher UV and visible transparency and electrical conductivity compared with those of pure In2O3 films. The influence of annealing atmosphere is investigated.

Assembly of mesoporous indium tin oxide electrodes from nano-hydroxide building blocks

“…The crystalline structure of the nanoparticles, however, neither corresponds to cubic ITO, nor can it be assigned to any known indium hydroxide, indium oxohydroxide or hydrated tin oxide phases. On the other hand, the observed diffraction pattern is very similar to that described by Qiu et al 24 for tin-doped indium hydroxide films obtained by a hydrogen peroxide-assisted method, which they assigned to an as-yet unknown hexagonal tin-doped indium hydroxide phase with lattice parameters a and c equaling 10.89 and 3.99 A, respectively. We compared the positions of the diffraction maxima calculated for this phase with those obtained for our particles (see Table S1 and Figs.…”

“…S1 and S2 in the Supplementary Information †). Although the correct crystal lattice could not be determined with complete certainty due to the significant broadening and overlapping of diffraction lines, the results indicate that the crystalline phase of as-prepared indium tin hydroxide is structurally closely related to the hexagonal phase proposed by Qui et al 24 (see Experimental Part in the Supplementary information for details †). The line broadening (FWHM) values (Table S1 †), estimated from the results of individual profile fitting, show that the diffraction lines at 2Q equaling 22.3 and 45.5 are much narrower than the other lines.…”

“…The volume-averaged domain size (D hkl ) in the hkl direction corresponding to those two lines (direction 00l in the hexagonal lattice in ref. 24) was roughly estimated using the Scherrer equation to be about 8 nm. Crystallite sizes in the perpendicular hkl directions are two to three times smaller (about 3 nm).…”

“…19,[21][22][23] The utility of this approach for the formation of conducting tin-doped indium oxide nanostructures is much less explored, but several reports already demonstrate their great potential as primary units for nanostructure formation. Qiu et al 24 described the formation of indium tin hydroxide films with tunable rod-like morphology by deposition of in situ formed hydroxide units. Kovtyukhova et al 25,26 applied electrochemically initiated hydrolysis for preparing indium tin hydroxide nanostructures, which could subsequently be transformed into ITO films without a significant change in morphology.…”

Highly sensitive room-temperature CO gas sensors: Pt and Pd nanoparticle-decorated In2O3 flower-like nanobundles

“…34,35 When In(OH) 3 nanochains come close to each other, a condensation reaction could occur between the -OH groups on the surfaces to build chemical bonds, oxo (-O-) bridges, for the oriented attachment. 34,36 By high-temperature heat treatments, the flower-like shape of the In(OH) 3 NBs was maintained as shown in Fig. 2a nature of the polycrystalline structure.…”