Sn-doped polyhedral In2O3 particles: Synthesis, characterization, and origins of luminous emission in wide visible range
Graphical abstract
With more oxygen vacancies and tin doping. ITO particles can exhibit a better CL performance. Sn donor level near the conduction band edge plays an important role in luminous emission in wide visible range.
Highlights
► Polyhedral ITO particles synthesized by thermal evaporation using SnO as dopant. ► Broad visible luminous emission around 570 nm. ► Sn donor level plays an important role in the visible emission. ► ITO particles with more oxygen vacancies have better CL performance in visible range.
Introduction
As an important and well-known semiconducting oxide (TCO), indium oxide (IO) has been broadly applied to displays [1], [2], organic light-emitting diodes (OLEDs) [3], solar cells [4], [5], functional glass [6], [7], and energy efficient windows [8], [9]. Researchers have synthesized pure octahedronal IO particles and IO pyramids by liquid-phase method or by physical evaporation of indium with or without Au as catalyst [10], [11], [12], [13], [14], [15], [16]. IO octahedrons precipitated on Sn-doped indium oxide substrate were also reported [17]. The Sn-doped indium oxide known as indium tin oxides (ITO) is another kind of promising n-type transparent semiconductor material in screen display techniques [18], [19]. ITO powder of high purity and fine grain size is largely in demand for the preparation of ITO targets [20], [21]. However, few articles were reported on the polyhedral ITO particles.
In this article, we developed a simple thermal evaporation of indium grains to prepare Sn-doped octahedronal and tetrakaidecahedronal In2O3 particles using SnO as dopant without the presence of Au catalyst. Apart from photoluminescence (PL) spectroscopy, cathodoluminescence (CL) spectroscopy was also employed to characterize the luminous emission features of samples. Both samples exhibit broad visible luminous emission peak around 570 nm, which has potential application in screen display techniques.
Section snippets
Synthesis
The synthesis of samples was carried out in a horizontal alumina tube furnace. High purity indium grains (5 N) and a mixture of SnO powder and graphite powder (both are analytic purity) were separately placed in a ceramic boat, which was located in the heating center of alumina tube. A Si substrate was put 25 cm away from the ceramic boat to collect the products. Prior to heating, the alumina tube was sealed and pumped down to a pressure of 10−3 Torr. Argon (Ar) gas was then introduced with a flow
Results and discussion
The morphologies of sample A and sample B are shown in Fig. 1(a) and (b), respectively. Fig. 1(a) reveals the octahedronal particles attached by tiny particles. In Fig. 1(b), the tetrakaidecahedronal particles exhibit six more surfaces than the octahedronal particles in Fig. 1(a). The diameters of two kinds of particles are averagely estimated about 450 nm. The EDS spectra of both samples were obtained under FESEM. It was found that sample A and sample B consist of elemental In, Sn, and O shown
Conclusions
Sn-doped polyhedral In2O3 particles were synthesized by simple thermal evaporation of indium grain using SnO as dopant. The Sn-doped tetrakaidecahedronal In2O3 particle had six more {0 0 1} crystal faces than the octahedronal one. The Sn donor level is important for the luminous emission in visible range. The major part of the broad visible luminous emission originates from indium interstitial and antisite oxygen in our samples. With more singly ionized oxygen vacancies and tin doping, ITO
Acknowledgment
This work was financially supported by the National Natural Science Foundation of China (NSFC, No. 21071039).
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