Quantum Dots as Material for Efficient Energy Harvesting

The essence of the photovoltaic effect is the generation of electric current with the help of light. Absorption of a quantum of the energy of light (photon) generates the appearance of an electron in the conduction band and holes in the valence band. The illumination of the material, in general, is not uniform, which leads to the appearance of spatially inhomogeneous charge in the band valence and conductivity. Besides, electrons and holes generally diffuse with different velocities, which leads to the creation of a separated space charge and generation of an electric field (sometimes called the Dember field). This field inhibits further separation of cargo. The reverse processes also take place in the system, i.e. electron recombination and holes. These processes are destructive from the point of view of photovoltaics and should be minimized, which is achieved; thanks to the spatial separation of electrons and holes. The point is that electrons and holes were carried away from the area where they formed as quickly as possible, yes to prevent their spontaneous recombination. The use of semiconductor quantum dots introduced into the photoelectric material is currently a very important and effective way to increase the efficiency of photoelectric devices and photovoltaic cells. This is due to the fact that in semiconductor photoelectric materials with no quantum dots, there is always some upper limit of the wavelength λgrgr≃1,24/EgeV for absorbed light, above which the light is not absorbed

IIIrd Generation Solar Cell

Light harvesting for generation of electric energy is one of the most important research topics in applied sciences. First, for an efficient harvesting one needs a material with a broad light absorption window having a strong overlap with the sunlight spectrum. Second, one needs an efficient conversion of photoexcited carriers into produced current or voltage which can be used for applied purposes. The maximum light conversion coefficient in semiconductor systems is designated by so called Shockley-Queisser law, which is around 32% for an optimal bandgap value of 1,2–1,3 eV. However the efficiency may be increased using a solutions based on semiconductor nano materials such as quantum dots. Solar cells based on such a structures are included in the group of 3rd generation solar sell. 3rd generation solar cell encompasses multiple materials as a base of cell, such as: perovskite, organic, polymers and biomimetics. The most promising and in the same time most discussed are quantum dots and perovskite. Both material has a potential to revolutionize the solar cell industry due to their wide absorption range and high conversion coefficient. Nonetheless before the most common used material in photovoltaic namely silicon is replace one must overcome few major issues such as: stability and lifetime for at least 5 to 10 years or more, manufacturing process for a large surfaces and low production cost as well as recycling after the time of optimal use

Solar chargers based on new dye-based photovoltaic modules and new supercapacitors

Electricity storage is one of the best-known methods of balancing the energy supply and demand at a given moment. The article presents an innovative solution for the construction of an electric energy storage device obtained from an innovative photovoltaic panel made of new dye-based photovoltaic modules and newly developed supercapacitors – which can be used as an emergency power source. In the paper, for the first time, we focused on the successful paring of new dye-sensitized solar cell (DSSC) with novel supercapacitors. In the first step, a microprocessor stand was constructed using Artificial Intelligence algorithms to control the parameters of the environment, as well as the solar charger composed of six DSSC cells with the dimensions of 100_100 mm and 126 CR2032 coin cells with a total capacitance of 60 F containing redox-active aqueous electrolyte. It was proven that the solar charger store enough energy to power, i.e. SOS transmitter or igniters, using a 5 V signal

Efficiency boost in dye-sensitized solar cells by post- annealing UV-ozone treatment of TiO2TiO_{2} mesoporous layer

The organic residues on titanium(IV) oxide may be a significant factor that decreases the efficiency of dye-sensitized solar cells (DSSC). Here, we suggest the UV-ozone cleaning process to remove impurities from the surface of $TiO_{2}$ nanoparticles before dye-sensitizing. Data obtained from scanning electron microscopy, Kelvin probe, Fourier-transform infrared spectroscopy, and Raman spectroscopy showed that the amounts of organic contamination were successfully reduced. Additionally, the UV-VIS spectrophotometry, spectrofluorometry, and secondary ion mass spectrometry proved that after ozonization, the dyeing process was relevantly enhanced. Due to the removal of organics, the power conversion efficiency (PCE) of the prepared DSSC devices was boosted from 4.59% to 5.89%, which was mostly caused by the increment of short circuit current (Jsc) and slight improvement of the open circuit voltage (Voc)

Photovoltaic road and rail noise barriers at different environmental and soil conditions, including mining terrains

Regulations and standards concerning noise road and rail barriers are presented together with an actual state-of-the-art in Europe. Application of photovoltaics to such infrastructure are considered. The targets of international CEFRABID research project, realised within ERA-SOLAR.NET European program, and concerning photovoltaic road and rail noise barriers for Austria, Cyprus, Poland and Spain, at different environmental and soil conditions, including mining terrains are shortly presented

Alternative method of making electrical connections in the 1st and 3rd generation modules as an effective way to improve module efficiency and reduce production costs

In this work, we propose a new method for manufacturing busbars in photovoltaic modules for different solar cell generations, focusing on 1st and 3rd generations. The method is based on high-pressure spray coating using nanometric metallic powder. Our focus is primarily on optimizing conductive paths for applications involving conductive layers used in 3rd generation solar cells, such as quantum dot solar cell, dye-sensitized solar cell, and silicon-based solar cells on glass-glass architecture for buildingintegrated photovoltaic. The advantages of the proposed method include the possibility of reducing the material quantity in the conductive paths and creating various shapes on the surface, including bent substrates. This paper examines the influence of the proposed high-pressure spraying technique using metallic particles on the morphology of the resulting conductive paths, interface characteristics, and electrical parameters. Conductive paths were created on four different layers commonly used in photovoltaic systems, including transparent conductive oxide, Cu, Ti, and atomic layer deposition processed Al2O3. The use of high-pressure technology enables the production of conductive layers with strong adhesion to the substrate and precise control of the spatial parameters of conductive paths. Furthermore, the temperature recorded during the deposition process does not exceed 385 K, making this technique suitable for various types of substrates, including glass and silicon. Additionally, the produced layers exhibit low resistance, measuring less than 0.3 Ω. Finally, the mechanical resistance, as determined through tearing tests, as well as environmental and time stability, have been confirmed for the produced paths

Determining the Effectiveness of Street Cleaning with the Use of Decision Analysis and Research on the Reduction in Chloride in Waste

Waste from street cleaning is usually of a fine fraction below 10 mm and varies greatly in both quantity and composition. It may be composed of chlorides, especially for that resulting during winter due to the use of street de-icing agents. Chlorides can cause the salinization of surface water and groundwater, and the salinization of soils, which in turn lead to the deterioration of water purity and a decrease in biodiversity of aquatic organisms, changes in microbiological structure, and increases in toxicity of metals. Therefore, it is very important to determine the level of salinity in stored waste and its impact on the environment. The present study was conducted in a city of about 55,000 inhabitants. The highest chloride concentrations were observed after winter in waste from street and sidewalk cleaning around the sewer gullies, amounting to 1468 mg/dm3. The lowest chloride concentration in this waste occurred in summer and amounted to 35 mg/dm3. The multi-criteria analysis indicated that the most beneficial form of street cleaning and, thus, of reductions in chloride concentration in the waste from street cleaning, would be sweeping and daily washing. The objective of this research was to determine the amount of chlorides in sweepings on an annual basis in order to determine the potential risks associated with their impact on select aspects of the environment and to evaluate the frequency of necessary cleaning for city streets, considering the effects. The methodology used was a multi-criteria evaluation, which as a decision analysis, allowed us to determine the frequency of cleaning and washing of streets, in such a way that an ecological effect is achieved with simultaneous economic efficiency

Determining the Effectiveness of Street Cleaning with the Use of Decision Analysis and Research on the Reduction in Chloride in Waste

Waste from street cleaning is usually of a fine fraction below 10 mm and varies greatly in both quantity and composition. It may be composed of chlorides, especially for that resulting during winter due to the use of street de-icing agents. Chlorides can cause the salinization of surface water and groundwater, and the salinization of soils, which in turn lead to the deterioration of water purity and a decrease in biodiversity of aquatic organisms, changes in microbiological structure, and increases in toxicity of metals. Therefore, it is very important to determine the level of salinity in stored waste and its impact on the environment. The present study was conducted in a city of about 55,000 inhabitants. The highest chloride concentrations were observed after winter in waste from street and sidewalk cleaning around the sewer gullies, amounting to 1468 mg/dm3. The lowest chloride concentration in this waste occurred in summer and amounted to 35 mg/dm3. The multi-criteria analysis indicated that the most beneficial form of street cleaning and, thus, of reductions in chloride concentration in the waste from street cleaning, would be sweeping and daily washing. The objective of this research was to determine the amount of chlorides in sweepings on an annual basis in order to determine the potential risks associated with their impact on select aspects of the environment and to evaluate the frequency of necessary cleaning for city streets, considering the effects. The methodology used was a multi-criteria evaluation, which as a decision analysis, allowed us to determine the frequency of cleaning and washing of streets, in such a way that an ecological effect is achieved with simultaneous economic efficiency