Narrow Results

Carbon films have been deposited on quartz and single-crystal silicon substrates by pulsed laser deposition technique. The soot for the target was obtained from burning camphor, a natural source. The effect of nitrogen (N) incorporation in camphoric carbon film is investigated. Optical gap for the undoped film is about 0.95 eV. The optical gap remains unchanged for low N content and decreases to about 0.7 eV. With higher N content, the optical gap increases. The resistivity of the carbon film increases with N content, initially and decreases with higher N content up till the film that is deposited at 30 mTorr. The results indicate successful doping for the film deposited at low nitrogen content. The J–V characteristics of N-incorporated carbon/silicon photovoltaic cells under illumination are observed to improve upon N-incorporation in the carbon layer.

In this study, semi-flexible dye-sensitized solar cell (DSSC) and flexible DSSC are examined comparatively. First, TiO₂ paste with HCl was prepared and flexible photoanodes were produced by coating this paste on the indium tin oxide-coated poly(ethylene terephthalate) (ITO/PET) flexible substrates under the same conditions. These flexible photoanodes have been sensitized with Ruthenizer N719 dye at room temperature for 48h. The Pt was used as the back-electrode. The first back-electrode was fabricated for semi-flexible DSSC by spraying Pt on the fluorine-doped tin oxide (FTO). The second back-electrode was fabricated for flexible DSSC by coating Pt on ITO/PET using the chemical reduction method. The flexible photoanodes and Pt counter-electrodes have been combined. The photovoltaic performance of the semi-flexible DSSC was compared to the flexible DSSC.

Perovskite solar cells have recently been considered to be an auspicious candidate for the advancement of future photovoltaic research. A power conversion efficiency (PCE) as high as 22% has been reported to be reached, which can be obtained through an inexpensive and high-throughput solution process. Modeling and simulation of these cells can provide deep insights into their fundamental mechanism of performance. In this paper, two different perovskite solar cells are designed by using COMSOL Multiphysics to optimize the thickness of each layer and the overall thickness of the cell. Electric potential, electron and hole concentrations, generation rate, open-circuit voltage, short-circuit current and the output power were calculated. Finally, PCEs of 20.7% and 26.1% were predicted. Afterwards, according to the simulation results, the role of the hole transport layer (HTL) was investigated and the optimum thickness of the perovskite was measured to be 200nm for both cells. Therefore, the spin coating settings are selected so that a coating with this thickness for cell 1 is deposited. In order to compare the performance of HTM layer, solar cells with a Spiro-OMeTAD HTM and without the HTM layer in their structure were fabricated. According to the obtained photovoltaic properties, the solar cell made with Spiro-OMeTAD has a more favorable open-circuit voltage ($V_{\mathrm{\text{OC}}}$), short-circuit current density ($J_{\mathrm{\text{SC}}}$), fill factor (FF) and PCE compared to the cell without the HTM layer. Also, hysteresis depends strongly on the perovskite grain size, because large average grain size will lead to an increase in the grain’s contact surface area and a decrease in the density of grain boundaries. Finally, according to the results, it was concluded that, in the presence of a hole transport layer, ion transfer was better and ion accumulation was less intense, and therefore, the hysteresis decreases.

This paper simulated the optimum solar cell power conversion efficiency-based planar solar surface morphology with various solar cell absorber structures. The spectral light intensity, reflected, absorbed, and transmission coefficients versus wavelength band spectrum varied from 300nm to 1300nm through the visible to near-infrared regions. The optimum solar cell performance parameters or key parameters are studied with different solar cell structure designs based on different surface contact and back contact layers. Cumulative generation current, cumulative electron–hole pair generation rate and electron–hole pair generation rate are clarified versus substrate depth for various solar cell structure designs. The absorbed current in substrate is optimized for various solar cell structure designs. Maximum power voltage and current are also optimized for the proposed solar cell structure design. The effective solar cell power efficiency is also demonstrated based on the optimized maximum power current and maximum power voltage.

A novel inorganic/organic nanocomposite film composed of Si nanoparticles (NPs) and poly-(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT–PSS) is obtained from a simple mechanical mixture of Si NPs powder and aqueous PEDOT–PSS solution. Employing this composite film as a counter electrode, dye-sensitized solar cell (DSSC) exhibits an efficiency of 5.7% and a fill factor of 0.51, which are much higher than these of DSSC using pristine PEDOT–PSS electrode (2.9% and 0.25, respectively). The improvements in the photovoltaic performance of the former are primarily derived from improved electrocatalytic performance of the electrode, as evidenced by electrochemical measurements, the composite electrode has lower impedance and higher electrocatalytic activity when in comparison with pristine PEDOT–PSS electrode. These improvements are primarily deriving from the increased electrochemical surface by the addition of Si NPs. The characteristics of Si NPs/PEDOT–PSS composite counter electrode reveal its potential for the use of low-cost and stable Pt-free counter electrode materials. In addition, the results achieved in this work also provide a facile and efficient approach to improve the photovoltaic performance of DSSCs using PEDOT–PSS electrodes.