Tunable Photoelectrochemical Properties of Chalcopyrite AgInS2 Nanoparticles Size-Controlled with a Photoetching Technique

• Published in: Journal of physical chemistry. C Vol. 116; no. 41; pp. 21895 - 21902
• Main Authors: Torimoto, Tsukasa, Tada, Masaki, Dai, Meilin, Kameyama, Tatsuya, Suzuki, Shushi, Kuwabata, Susumu
• Format: Journal Article
• Language: English
• Published: Columbus, OH American Chemical Society 18.10.2012
• Subjects: Chemical synthesis methods; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in multilayers, nanoscale materials and structures; Exact sciences and technology; Materials science; Methods of nanofabrication; Nanocrystalline materials; Nanopowders; Nanoscale materials and structures: fabrication and characterization; Physics; Photoelectrochemical effect; Particle size; Thermal decomposition; Photoetching; Quantum size effect; Nanoparticles; Chalcopyrite; Aqueous solutions; Silver Indium Sulfides Mixed; n type semiconductor; Illumination; Photoconductivity; Nanomaterial synthesis; Crystal structure
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp307305q

Size-selective photoetching enabled precise size control of chalcopyrite AgInS2 nanoparticles in a basic aqueous solution containing ammonia by selecting the wavelength of monochromatic irradiation light in the range between 650 and 520 nm. The energy gap of the photoetched particles was enlarged from 1.8 to 2.4 eV with a decrease in particle size from 5.1 to 2.7 nm due to the quantum size effect, while the crystal structure and chemical composition of the particles were unchanged after the photoetching processes. AgInS2 nanoparticle-immobilized electrodes exhibited an anodic photocurrent similar to that of n-type semiconductors, the onset potential of which was negatively shifted with a decrease in particle size. Potentials of the conduction band edge (E CB) and the valence band edge (E VB) of AgInS2 nanoparticles were estimated from their photoelectrochemical measurements, and they exhibited remarkable size dependence: with a decrease in particle size from 5.1 to 2.7 nm, E CB was shifted negatively from −0.6 to −1.0 V vs Ag/AgCl, accompanied by a positive shift of E VB from 1.3 to 1.7 V vs Ag/AgCl.