Anisotropic nonspherical nanomaterials have attracted a special attention in material science because of their unique chemical, physical, and optical properties, which are greatly affected by their shape and size. [1] Thus, many efforts have been made to synthesize nanorods and nanowires. [2] Compared with one-dimensional (1D) structures, 2D nanomaterials such as nanoplates and nanodisks have been relatively little explored and require further investigation. To date the following nanoplates have been prepared: hexagonal [3] (Co(OH) 2 , Cu 2 S, SbTe 3 , Bi 2 Te 3 , etc.), trigonal [4] (Au, Ag, Pd, Bi, Se, LaF 3 , etc.), square [5] (rare earth metals, Bi 2 WO 6 , etc.), and circular [6] (Ag, Co, etc.).
Over the last two decades, the chemical and physical properties of diverse semiconductor nanocrystals have been investigated. [7] Compared to the corresponding conventional bulk materials, semiconductor nanomaterials show unique optical, mechanical, electronic, and catalytic properties which are highly dependent on size and shape. Of the known semiconductor nanomaterials, perhaps the semiconducting metal chalcogenides have been studied most widely. In particular, most studies have focused on II-VI quantum dots (QDs) such as CdS, ZnS, and CdSe. [8] Moreover, I-VI QDs such as Ag 2 S and Cu 2 S have received significant attention. [9] Compared with the semiconductor nanomaterials mentioned above, the optical and electronic properties of metal chalcogenides which have 1:1.5 molar ratio of metal to chalcogenide in their unit cells have received comparatively little attention. These include In 2 S 3 , Bi 2 S 3 , and Sb 2 S 3 nanocrystals. [10] Indium sulfide (In 2 S 3 ) exists in three different crystalline forms: a-In 2 S 3 (defect cubic), b-In 2 S 3 (defect spinel), and g-In 2 S 3 (layered structure). [11] Of these, b-In 2 S 3 is an n-type semiconductor with a band gap of 2.0-2.3 eV and is stable above 420 8C. [12] Moreover, the unique luminescence properties of b-In 2 S 3 have enabled its use as a phosphor in display devices. [13] Furthermore, its photoconductive properties [14] make it a promising candidate for photovoltaic applications such as solar cells. Recently, it was reported that solar cell devices prepared by using b-In 2 S 3 as a buffer layer show 16.4 % conversion efficiency, which is very close to that of the standard CdS buffer layer. [15] Much effort has been made to replace highly toxic cadmium with other metals for environmental reasons. [16] A number of synthetic methods [17] have been developed to prepare b-In 2 S 3 , for example, direct reacting of the elements at high temperature, heating In 2 O 3 in H 2 S, thermal decomposition of organometallic precursors, and metathesis reaction between InCl 3 and Li 2 S. To fabricate thin films of b-In 2 S 3 for solar cell applications, several deposition techniques, such as organometallic chemical deposition, spray pyrolysis, and chemical bath deposition, have been developed. [18] b-In 2 S 3 can also be prepared by a wet chemical approach, [19] that is, by reaction between aqueous InCl 3 and H 2 S, (NH 4 ) 2 S, or NaSH; by laser-induced formation of In 2 S 3 from sodium polysulfide in aqueous solution; by using red light and Na 2 S; by forming colloidal particles in reverse micelles; by injecting H 2 S into In(ClO 4 ) 3 solution; by hydrothermal treatment of an acidic sol of InCl 3 and Na 2 S; or by sonochemical synthesis from InCl 3 and MeCSNH 2 . Recently, 3-nm b-In 2 S 3 nanocrystals were prepared by an arrested-precipitation method using aqueous InCl 3 solution and a thiol stabilizer. [20] However, as far as we are aware, the synthesis of b-In 2 S 3 in organic media