Search

The presented paper describes the study of ligand-exchange dependent properties of mercury chalcogenides (HgS, HgTe) colloidal quantum-dot thin films. Thin films of colloidal quantum dots of mercury telluride and mercury sulfide were prepared using a layer-by-layer deposition technique applying dip-coating and spin-coating methods. The impact of the synthetic procedure of quantum dots, solvent and concentration of colloidal solution on the thin films’ properties was analyzed. By using concentrated colloidal solutions in tetrachloroethylene, we succeeded in the preparation of homogeneous thin films with minimal roughness. The surface morphology and thickness of the thin films were determined using AFM. The voltage–current characteristics of photosensitive devices applying various ligand exchanges were investigated.

There is currently an energy crisis that has led to photovoltaic operators maximizing their resources, making soiling a problem to consider in order to ensure project profitability. Energy production costs are strongly affected by the use of scarcely efficient cleaning techniques that are not suitable for a particular type of contaminant, climate, and installation. This paper introduces a technology that is suitable for studying soiling, thus decreasing the number of variables studied and reliable results were obtained. Our attention is focused on deposited material physicochemistry, local geology, and installation effects. Analysis via scanning electron microscopy and pits revealed a similarity between local geological processes and module soiling, with gypsum being responsible for soil and module cementation. Analysis with Atomic Force Microscopy confirms the cementation effect and crust formation on the lower part of the photovoltaic glass, the latter concentrating in the greatest amount of cemented material. Using a solar simulator, the characteristic curves produced by the cemented material were studied, and it was determined that the lower part of the glass produced the greatest losses (27%). Thus, a non-uniformity deposition was generated, creating resistance between the cells. From the data obtained, it was possible to make recommendations regarding making decisions about plant cleaning, instead of only considering the physicochemical analysis of the deposited material.