Effect of the non-toxic Ag2S quantum dots size on their optical properties for environment-friendly applications

In this work, different sizes of Ag2S nanoparticles as a non-toxic semiconductor are prepared onto TiO2 (Titania) electrodes using successive ionic layer adsorption and reaction (SILAR) method for environmental-friendly applications. The surface morphology of the prepared Ag2S quantum dots (QDs) has been investigated using a scanning electron microscope (SEM). The structural properties of the prepared Ag2S photoanodes are studied using an energy dispersive X-ray spectrometer and X-ray diffractometer. The XRD measurements show the formation of the crystalline monoclinic acanthite phase of Ag2S (alpha-Ag2S). The optical properties of the prepared photoanodes were measured using a UV-visible spectrophotometer. The deduced energy band gap of the Ag2S photoanodes decreases from 3.20 eV to 1.31 eV as the number of SILAR deposition cycles increases from 1 to 9 cycles. This result is mainly attributed to the increase in the size of Ag2S QDs. The prepared Ag2S QDs photoanodes were utilized to fabricate Ag2S QDs sensitized solar cells (QDSSCs). The photovoltaic performance of the assembled QDSSCs is studied under AM1.5 conditions (100 mW/cm(2)). The optimal photovoltaic performance is achieved for six SILAR deposition cycles. This result is mainly attributed to the increase in the absorption of the incident solar power. Ag2S QDSSCs show good reproducibility with rapid sensitivity undercutting ON-OFF illumination.