Preparation and Photochemical Properties of Highly Luminescent ZnS-AgInS2 Solid Solution Nanoparticles

  • Porf Tsukasa Torimoto, Graduate School of Engineering, Nagoya University, Japan
  • Dr Ken-ichi Okazaki, Graduate School of Engineering, Nagoya University, Japan
  • Mr Tomohiro Adachi, Graduate School of Engineering, Nagoya University, Japan
  • Prof Tamaki Shibayama, Center for Advanced Research of Energy Conversion Materials, Hokkaido University, Japan
  • Prof Bunsho Ohtani, Catalysis Research Center, Hokkaido University, Japan
  • Prof Akihiko Kudo, Faculty of Science, Tokyo University of Science, Japan
  • Prof Susumu Kuwabata, Graduate School of Engineering, Osaka University, Japan

    • Semiconductor nanoparticles, such as CdSe and CdTe, have attracted much attention, because they exhibit the intense band gap emission and the peak wavelength can be adjusted by controlling particle size. In this paper, we report the preparation of novel ZnS-AgInS2 solid solution (ZAIS) nanoparticles and their photochemical properties.
    ZAIS nanoparticles were synthesized by the thermal decomposition of (AgIn)xZn2(1-x)(S2CN(C2H5)2)4 precursors in a hot oleylamine solution (180 oC). The resulting suspension was subjected to centrifugation to remove large particles. ZAIS nanoparticles were separated from the supernatant by addition of methanol.
    TEM observation revealed that spherical nanoparticles having clear lattice fringes were formed regardless of the chemical composition of precursors. The average sizes were determined to be 4.4, 4.4 and 4.1 nm at x=1.0, 0.6 and 0.4, respectively. X-ray powder diffraction analyses revealed that the fraction of ZnS in ZAIS nanoparticles was enlarged with an increase in the content of Zn in the precursors used. The particle surface was covered by oleylamine to prevent the coalescence between nanoparticles. The absorption onset of particles were blue-shifted from ca. 700 to ca. 500 nm with a decrease in x, indicating that the energy gap was enlarged with an increase in the fraction of ZnS in solid solution. The ZAIS nanoparticles exhibited intense photoluminescence at room temperature. The peak wavelength of PL was adjustable between 720 and 540 nm, depending on the composition of precursors used. The highest quantum yield of ca. 24% was obtained for ZAIS nanoparticles prepared with x= 0.86.