Plasmonic Effect in Photoelectrochemical Cells

Two types of third-generation photovoltaic (PV) cells are sensitized by dyes and quantum dots (QDs), the former being dye-sensitized solar cell abbreviated as DSSC. The second is the quantum dot-sensitized solar cell or QDSSC. There are three main components in DSSC and QDSSC. The photoanode is the component where the light is being absorbed either by molecules of the dye or by the quantum dots (QDs). The sensitizers are attached on the semiconductor (normally TiO2) surface. The conduction band (CB) of the semiconducting material should be at a level lower than the lowest unoccupied molecular orbital (LUMO) of the dye molecules or CB of QDs for fast electron transfer. Incorporation of plasmonic materials into the photoanode can increase light absorption efficiency by surface plasmon effect and thus improve the efficiency of the DSSCs and QDSSCs. Plasmonic materials that have been employed include gold (Au), silver (Ag) and aluminum (Al) nanoparticles (NPs). Different NPs exhibit different effects on the cell parameters. Covering the NPs with a thin wide bandgap semiconducting film is necessary to protect the plasmonic NP materials from the corrosive nature of the electrolyte

Third-Generation-Sensitized Solar Cells

The need to produce renewable energy with low production cost is indispensable in making the dream of avoiding undue reliance on non-renewable energy a reality. The emergence of a third-generation photovoltaic technology that is still in the infant stage gives hope for such a dream. Solar cells sensitized by dyes, quantum dots and perovskites are considered to be third-generation technological devices. This research focuses on the development of suitable and reliable sensitizers to widen electromagnetic (EM) wave absorption and to ensure stability of the photovoltaic system. This article discusses the basic principles and the progress in sensitized photovoltaics

Improvement of dye sensitized solar cells efficiency utilizing diethyl carbonate in PVA based gel polymer electrolytes

Low conductivity of gel polymer electrolytes (GPEs) containing double iodide salts is critical for efficiency in dye-sensitized solar cells (DSSCs). The presence of diethyl carbonate (DEC) plasticizer affects the amorphousness and ionic conductivity of polyvinyl alcohol (PVA)-based GPEs and DSSCs performance. In this work, PVA-based GPEs containing a variation of DEC have been produced, characterized, and applied in the DSSCs fabrication. The structural properties of GPEs were analyzed using X-ray diffraction (XRD). The ionic conductivity was determined from electrical impedance spectroscopy (EIS). Based on XRD, GPEs for all prepared compositions have been identified as an amorphous phase. From the EIS measurement, it was found that GPE with the composition of 5.46 PVA - 8.19 EC - 10.92 PC - 60.06 DMSO - 5.73 TPAI - 5.73 KI - 1.34 I2 - 2.57 DEC (in wt. %) having highest conductivity of 11.19 ± 0.20 mS cm-1 with activation energy, Ea of 0.09 eV. The graph of conductivity versus temperature following the Arrhenius rule has been plotted. The GPEs dominate the highest conductive with 2.57% of DEC and showed the DSSCs efficiency of 6.42%. Common DSSCs parameters resulted in short-circuit current density (Jsc) of 17.58 mA cm-2, fill factor (ff) of 0.63, and open-circuit voltage (Voc) of 0.58 V. In conclusion, DEC improves the ionic conductivity as well as amorphous properties of the GPE, and therefore enhance the DSSCs' efficiency

Polyacrylonitrile gel polymer electrolyte based dye sensitized solar cells for a prototype solar panel

Polyacrylonitrile (PAN) based gel polymer electrolytes (GPE) were prepared using lithium iodide (LiI), 1-butyl-3-methylimidazolium iodide (BMII) and tetrapropyl ammonium iodide (TPAI). The LiI mass fraction in the electrolyte was varied while keeping the masses of other components constant in order to enhance the solar cell performance. The addition of 4.61 wt.% LiI in the GPE increased the electrolyte room temperature ionic conductivity from (2.32 ± 0.02) to (3.91 ± 0.04) mS cm−1. The increase in conductivity with the addition of LiI salts was attributed to the increase in diffusion coefficient, mobility and number density of charge carriers as determined from Nyquist plot fitting. The incorporation of LiI salts in PAN-based GPE has enhanced the efficiency of the DSSC as expected. The best cell performance was obtained with an electrolyte containing 4.61 wt.% LiI sandwiched between a single mesoporous layer of TiO2 soaked in N3 dye sensitizer and a platinum counter electrode, which showed a power conversion efficiency (PCE) of (5.4 ± 0.1) % with a short circuit current density (Jsc) of (21.0 ± 1.1) mA cm−2, an open circuit voltage (Voc) of (0.48 ± 0.02) V and a fill factor (FF) of (53.4 ± 0.9) %. The DSSCs with 4.61 wt.% of LiI have been used to fabricate prototype solar panels for operating small devices. The panels were assembled using a number of cells, each having an area of 2 cm × 2 cm, connected in series and parallel. The panel, consisting of a set of eight cells in series which was connected in parallel with another set of eight cells in series, produces an average power conversion efficiency of (3.7 ± 0.2)% with a maximum output power of (17.1 ± 0.9) mW

Ionic conductivity and related studies on chitosan-based electrolytes with application in solar cells / Mohd Hamdi Ali@Buraidah

The motivation in this work is to ensure that the chitosan biopolymer can be used as a host for ion conduction and used as an electrolyte in dye-sensitized solar cells (DSSCs). The conductivity of the chitosan-NH4I electrolytes was optimized by varying the NH4I concentration, blending chitosan with PVA and PEO and also by incorporating of ionic liquid (IL). The electrolytes were prepared by solution cast technique. FTIR results confirm complexation between polymer, NH4I and IL. Hydrogen bonding between chitosan and PVA and between chitosan and PEO are observed in the respective spectrum. XRD indicates that the amorphousness of pure chitosan, chitosan-PVA and chitosan-PEO films changes with NH4I concentration. The 55 wt.% chitosan-45 wt.% NH4I (Ch9) sample exhibits the highest room temperature conductivity of 3.73 × 10-7 S cm-1. Blending chitosan with PVA and PEO further increased conductivity. The 27.5 wt.% chitosan-27.5 wt.% PVA-45 wt.% NH4I (CV5) sample exhibits the highest conductivity of 1.77 × 10-7 S cm-1 at room temperature and the highest conducting sample in (chitosan-PEO)-NH4I system is 3.66 × 10-6 S cm-1 for sample containing 16.5 wt.% chitosan-38.5 wt.% PEO-45 wt.% NH4I (CEO7) electrolyte. Incorporating 50 wt.% IL into Ch9, the electrolyte CIL5 exhibits the highest room temperature conductivity of 3.43 × 10-5 S cm-1. The activation energy, EA for the highest conducting samples follows the order Ch9 (0.45 eV) < CV5 (0.38 eV) < CEO7 (0.31 eV) < CIL5 (0.25 eV). DSSCs were fabricated using natural dyes extracted from black rice, blueberry and red cabbage. The highest conducting samples from each system have been chosen in the fabrication DSSCs. Some iodine crystals were added to the electrolytes to produce the redox-mediator. Red cabbage DSSCs using CIL5(+I2) gel electrolyte exhibits the highest efficiency of 0.2 % compared to using CEO7(+I2) and CV5(+I2) gel electrolytes

Development on Solid Polymer Electrolytes for Electrochemical Devices

Electrochemical devices, especially energy storage, have been around for many decades. Liquid electrolytes (LEs), which are known for their volatility and flammability, are mostly used in the fabrication of the devices. Dye-sensitized solar cells (DSSCs) and quantum dot sensitized solar cells (QDSSCs) are also using electrochemical reaction to operate. Following the demand for green and safer energy sources to replace fossil energy, this has raised the research interest in solid-state electrochemical devices. Solid polymer electrolytes (SPEs) are among the candidates to replace the LEs. Hence, understanding the mechanism of ions’ transport in SPEs is crucial to achieve similar, if not better, performance to that of LEs. In this paper, the development of SPE from basic construction to electrolyte optimization, which includes polymer blending and adding various types of additives, such as plasticizers and fillers, is discussed

Effect of lithium iodide on the performance of dye sensitized solar cells (DSSC) using poly(ethylene oxide) (PEO)/poly(vinyl alcohol) (PVA) based gel polymer electrolytes

In this work, different concentrations of lithium iodide (LiI) have been added to the gel polymer electrolyte (GPE) containing PEO and PVA in equal ratio, tetrabutylammonium iodide (TBAI), ethylene carbonate (EC), dimethyl sulfoxide (DMSO) and iodine crystals (I2). The effect of introducing lithium iodide (LiI) into PEO-PVA blended GPE system having TBAI has been investigated in terms of optical, electrical, thermal and electrochemical characteristics. Fourier transform infrared (FTIR) spectroscopy has been carried out to study the interaction of LiI with the GPEs. The GPE without LiI showed the highest conductivity of 5.50 mS cm−1 at room temperature. With the incorporation of LiI, decrement in conductivity was observed. Dye-sensitized solar cells (DSSCs) with configuration FTO/TiO2/N3-dye/GPE/Pt/FTO have been fabricated and tested under white light of intensity 100 mW cm−2. The DSSC made of GPE with 1.34 wt% LiI exhibited highest efficiency, η of 6.26%

Studies of solvent effect on the conductivity of 2-mercaptopyridine-doped solid polymer blend electrolytes and its application in dye-sensitized solar cells

Solvents and electrolytes play an important role in the fabrication of dye-sensitized solar cells (DSSCs). We have studied the poly(ethylene oxide)-poly(methyl methacrylate)-KI-I2 (PEO-PMMA-KI-I2) polymer blend electrolytes prepared with different wt % of the 2-mercaptopyridine by solution casting method. The polymer electrolyte films were characterized by the FTIR, X-ray diffraction, electrochemical impedance and dielectric studies. FTIR spectra revealed complex formation between the PEO-PMMA-KI-I2 and 2-mercaptopyrindine. Ionic conductivity data revealed that 30% 2-mercaptopyridine-doped PEO-PMMA-KI-I2 electrolyte can show higher conductivity (1.55 × 10-5 S cm-1) than the other compositions (20, 40, and 50%). The effect of solvent on the conductivity and dielectric of solid polymer electrolytes was studied for the best composition (30% 2-mercaptopyridine-doped PEO-PMMA-KI-I2) electrolyte using various organic solvents such as acetonitrile, N,N-dimethylformamide, 2-butanone, chlorobenzene, dimethylsulfoxide, and isopropanol. We found that ac-conductivity and dielectric constant are higher for the polymer electrolytes processed from N,N-dimethylformamide. This observation revealed that the conductivity of the solid polymer electrolytes is dependent on the solvent used for processing and the dielectric constant of the film. The photo-conversion efficiency of dye-sensitized solar cells fabricated using the optimized polymer electrolytes was 3.0% under an illumination of 100 mW cm-2. The study suggests that N,N-dimethylformamide is a good solvent for the polymer electrolyte processing due to higher ac-conductivity beneficial for the electrochemical device applications