Synthesis of AgInS2 nanocrystal ink and its photoelectrical application.

This paper reports a hot-injection method of preparing AgInS2 nanocrystals with different sizes and morphologies, starting with the capping agents of oleylamine and dodecylthiol, and varying the reaction conditions. The effects of the temperature and time on the growth of AgInS2 nanocrystals are investigated. These parameters have a tremendous impact on the size and morphology of the nanocrystals, allowing the controlled synthesis of shapes including nanoparticles and nanorods. It has been found that the size of the nanoparticles and nanorods can be controlled by changing the time of nanocrystal growth. The evolution from nanoparticles to nanorods can be controlled by the reaction temperature. The possible formation mechanism and growth process of the AgInS2 nanocrystals are discussed based on the experimental results. The AgInS2 nanocrystal ink with a bandgap of 1.90 eV can produce crack-free films. As a proof-of-concept, thin film solar cells made by using such AgInS2 films as absorber layers are tested for their viability as a type of solar cell material and are found to exhibit a measurable photovoltaic response.