Photoelectrochemical and Corrosion Study of n‐Type SnSSe

Abstract

Single crystals of n-type SnS~Se2_x (x = 1.04) obtained both by transport and Bridgman methods exhibit an energy gap of 1.53 eV. The flatband potential is pH dependent, and its values in acidic and alkaline solutions are, respectively, 0.06 and -0.6V (SCE). In the dark, SnSSe is stable in acidic medium, but the stability decreases as pH increases. It is also unstable in acidic solutions containing the oxidizing form of a redox reagent with a sufficiently positive redox potential (ca. more positive than 0.8V/SCE). The presence of an oxidizing form of a redox couple in alkaline medium enhances the already existing corrosion reaction. The corrosion reaction is accompanied with an anodic current. The corrosion rate as well as the magnitude of the anodic current depends on pH and the concentration of the oxidizing state of the couple. Light-driven reactions in both acidic and alkaline media are corrosion reactions. However, decomposition may be avoided in acidic solution containing potassium iodide.The solid solution SnSxSe2_x can be prepared over the entire composition range from SnS2 to SnSe2. Compounds obtained are layered semiconductor with CdI.,-type structure. Optical properties of the mixed series SnSxSe2 x (where 0 < x < 2) have already been studied (1). Indirect energy gaps obtained vary linearly between SnSe2 (1.09 eV) and SnS,.sSe0.5 (1.75 eV). A deviation from linearity is observed between SnS1.sSe0.5 and SnS~ (2.22 eV). Photoelectrochemical properties of SnS2 have already been studied (2), and it seems interesting to consider the ternary compound.Although this ternary compound could present a particular interest in solar energy conversion because of its adjustable energy gap, it has not yet received attention in photoelectrochemistry. SnSSe, whose reported energy gap is 1.52 eV (1), which is an optimum value for solar spectrum, could be an interesting candidate for solar energy conversion into electrical or chemical energy. ExperimentalSnSxSe2_x single crystals were obtained both by transport and Bridgman methods. In both cases, stoichiometric amounts of purified tin sulfur and selenium were used. In the transport method, iodine and bromine were the transporting agents. The charge zone was at 630~ and the transport zone at 580~ Single crystals of SnS~Se2 x (3 • 3 • 0.1 ram) were obtained within a week. In the Bridgman method, the transport zone was fixed at 780~ and the temperature gradient was 70~ Ingots of 10 cm length with 1 cm diam were obtained. Microprobe analysis indicated that the composition of the samples prepared by tranport was x = 1.04. For those prepared by Bridgman technique, the same composition was found for the higher part of the tube (x = 1.05). The composition for the lower and the central parts of the tube was approximately x = 1.2. Hall measurements gave a carrier concentration of 6 • 10 '7 cm -~3 and a resistivity of 0.36 ~-cm at room temperature for samples prepared by transport method, and a carrier concentration of 2 • 10 '" cm -:~ and a resistivity of 200 ~-cm for those prepared...

Stacked 2D nanoflake-structured thin films of chalcogenide SnSxSe(y−x) grown by spray pyrolysis: structural, optical and electrical properties

“…The drop in the carrier concentration in the films that were deposited at 425 °C and 450 °C might be attributed to the appearance of the second phase. The carrier concentration for the SnSSe deposited at 400 °C was two orders of magnitude higher than the one obtained by Perluzzo et al and compared favorably with the results of Fotouhi and Patel et al [11,32,34]. Hall and Seebeck coefficients of these materials showed that electron is the majority charge carrier; however, some fluctuations were observed in the films deposited at 425 °C and 450 °C.…”

High-performance ultra-violet phototransistors based on CVT-grown high quality SnS2flakes

“…19 Bulk SnS 2 crystals (usually representing a bandgap of 2.1-2.31 eV) have long been explored for possible applications in photovoltaics and photoelectrochemistry. 20,21 In addition, recent evidence has already pointed out the fascinating progress in applying 2D SnS 2 structures in lithium ion batteries, 22 eld-effect devices 23 and photodetectors, 24 benetting from the simple exfoliation from bulk crystals and the controlled bottom-up synthesis. 25,26 In particular, due to a considerable absorption coefficient (10 6 cm À1 ), 27 light sensors using 2D SnS 2 structures (most are obtained by CVD) exhibit superior UV-vis sensing performance such as high responsivity and good stability.…”

BilayerSnS2: Tunable stacking sequence by charging and loading pressure

“…As a member of this family, tin disulfide (SnS 2 ) was previously investigated in the bulk form for various applications. [28][29][30][31][32][33][34] After the emergence of novel 2D materials and improved production methods such as chemical vapor deposition, chemical and mechanical exfoliation, thinner structures of SnS 2 were synthesized for different applications. For example, a few nanometer-thick hexagonal SnS 2 was used for lithium storage in battery applications.…”