Evolution of In2S3 Nanoplates with Time

Indium sulfide is an emerging material for solar cell application and for this reason it has attracted much attention. Herein we report on the growth development of β-indium sulfide nanoparticles with reaction time. The nanostructures were synthesized by a conventional colloidal method and aliquots at 60, 90, 120 and 150 min were taken. The resultant nanostructures were characterized with x-ray diffraction, transmission electron microscopy, UV-Vis and photoluminescence spectroscopy. The variation of the reaction time resulted in particles with a defect tetragonal crystal structure however the morphology changed with time. The shapes evolved from spheres to 2D layered hexagonal nanoplates. 2D layered structures are often associated with the less stable high temperature γ-In2S3 phase, however in this study the γ phase was not observed. Hence the emergence of the layered structure was attributed to the surface strain experience by the particles over time and the possibility of the reaction conditions at 150 min being near the β-In2S3/ γ-In2S3 phase boundary. The optical properties of the OD structures were indicative of nanosized particles as the result of the blue-shifting of the band-edge. The sample synthesized at 150 min was more red-shifted than the other samples signifying larger particle sizes however the blue-shift from bulk was attributed to the thickness of the plates.