Tin(II) monosulfide (SnS) is a semiconductor material with an intermediate band gap, high absorption coefficient is the visible range, and consists of earth abundant, non-toxic elements. For these reasons, SnS has generated much interest for incorporation into optoelectronic devices, but little is known concerning the charge carrier dynamics, especially as measured by optical techniques. Here, phase-pure colloidal SnS has been synthesized by solution chemistry in the nanometer (SnS small nanoparticles), sub-micron (SnS medium nanosheets) and micron (SnS large sheets) size regimes and evaluated by time-resolved terahertz spectroscopy (TRTS), which is an optical, non-contact probe of the photoconductivity. Dropcast films of the SnS colloids were studied by TRTS both as-deposited and after thermal annealing. The results revealed that the charge carrier mobility of both the dropcast and annealed samples depends strongly on the size of the constituent colloids. The mobility of the SnS nanoparticles was determined to be 0.14 cm2/V-s while that for SnS large was found to be 20.3 cm2/V-s. Improvements in the charge carrier mobility were achieved for each of the three size regimes upon annealing the films with the largest improvement obtained for the SnS small and SnS medium sized samples.
Journal of Physical Chemistry C
Tin(II) monosulfide (SnS), Time-Resolved Terahertz Spectroscopy (TRTS), Charge Carrier Dynamics, Charge Carrier Mobility