We have studied transport properties (resistivity, Hall effect, thermopower, and thermal conductivity) of Bi2S3 and two new ternary bismuth sulfides, KBi6.33S10 and K2Bi8S13, to explore their potential for thermoelectric applications. While both Bi2S3 and K2Bi8S13 display an essentially metallic conduction, KBi6.33S10 has a distinctly semiconducting character. From the Hall measurements it follows that the dominant carriers in all three compounds are electrons and that the carrier density in K2Bi8S13 is almost 2 orders of magnitude larger than in Bi2S3 and KBi6.33S10 over the whole temperature range from 4 to 300 K. While the room temperature thermopowers of KBi6.33S10 and K2Bi8S13 are comparable (∼−100 μV/K), the thermopower of Bi2S3 is a factor of 3 larger. All three compounds are poor conductors of heat, in particular the thermal conductivity of KBi6.33S10 is some 25% lower than the thermal conductivity of Bi2Te3, the benchmark thermoelectric material. To make these materials useful thermoelectrics, wa...

Transport Properties of Bi2S3 and the Ternary Bismuth Sulfides KBi6.33S10 and K2Bi8S13

To improve the photoelectrochemical activity of WO3, Bi2S3/WO3 heterojunction films were designed by coupling WO3 films with varying amounts of urchin-like Bi2S3 nanospheres. The WO3 films were composed of WO3 nanoprism arrays, which were synthesized using a solvothermal method. After coating a single layer of Bi2S3 on top of the WO3 film, the resulting Bi2S3/WO3 heterojunction film showed enhanced photoelectrochemical activity. At 1.2 V vs. Ag/AgCl, the initial photocurrent density of the Bi2S3/WO3 heterojunction film with one layer of Bi2S3 was 1.33 mA cm−2 in 0.1 M Na2SO4 and 1.19 mA cm−2 in a 0.2 M NaCl mixed water–ethanol solution, which was 40% and 32% higher than the bare WO3 film under the same conditions, respectively. The optimal number of Bi2S3 layers for coupling with the WO3 film was found to be 3 layers, which had the highest photocurrent density and IPCE values. The photoelectrochemical activity of Bi2S3/WO3 heterojunction film was not stable for water oxidation due to photocorrosion in aqueous electrolyte, but it was stable in the NaCl mixed water–ethanol solution and a non-aqueous solution containing iodide/triiodide as a redox couple. The origin of enhanced photoelectrochemical activity of the Bi2S3/WO3 heterojunction film was primarily ascribed to the band potential matching between WO3 and Bi2S3, which is advantageous for charge separation.

Nanostructured Bi2S3/WO3 heterojunction films exhibiting enhanced photoelectrochemical performance

Preparation and characterization of spray deposited photoactive Sb2S3 and Sb2Se3 thin films using aqueous and non-aqueous media

Optoelectronic properties of chemically deposited Bi2S3 thin films and the photovoltaic performance of Bi2S3/P3OT solar cells

A method of preparing Bi2S3 nanoparticles by arrested precipitation is described. It is shown that varying the amount of stabiliser employed in the preparation controls the size of the particles. The as-prepared nanoparticles may be self-assembled on a tin oxide substrate. Photocurrent studies of the Bi2S3 modified electrode indicate that the presence of an oxidisable surface trap at approximately −0.15 V vs. Ag|AgCl|3.0 mol dm−3 NaCl. Photocurrent spectra indicate that the band edge of the Bi2S3 particles is only weakly dependent on particle size, consistent with a high effective mass of electrons in this material.

Jolly Lukose

Papers

Electrical and optical properties of bismuth sulphide [Bi2S3] thin films prepared by reactive evaporation