Sharif Digital Repository

In this work, a comparative study of hybrid solar cells based on P3HT and TiO2 nanofibers was accomplished. Electrospinning, a low cost production method for large area nanofibrous films, was employed to fabricate the organic-inorganic hybrid solar cells based on poly (3-hexylthiophene) and TiO2 nanofibers. The performance of the hybrid solar cells was analyzed for four density levels of TiO2 nanofibers which resulted in the average power conversion efficiency of about 0.0134% under AM 1.5 simulated illuminations (100 mWcm-2). It is found that the higher densities of TiO2 lead to more interface area and generating exciton, so the power conversion efficiency will be increased till the active... 

A comparative study has been made of hybrid solar cells based on poly(3-hexylthiophene) (P3HT) and different nano-structures of TiO2. Electrospinning, which is a low cost production method for large area nanofibrous films, was employed to fabricate TiO2 nanofibers and spin coating method was employed to fabricate organic-inorganic hybrid solar cells based on P3HT and TiO2 nanostructures. The performance of the hybrid solar cells was analyzed for four density levels of the TiO2 nanostructure. It was found that higher densities of TiO2 leads to more interface area and generates excitons, so that the power conversion efficiency increases to... 

Three new chromophores based on the triphenylamine (MM, DM, DN) with various novel electron withdrawing anchoring groups have been synthesized for use in dye-sensitized solar cells (DSSCs). The sensitizers were characterized by 1H and 13C NMR, Mass, UV–Vis, and electrochemical analysis. The HOMO and LUMO electron distributions of the sensitizers were calculated using density functional theory on a B3LYP level for geometry optimization. The DSSC device based on DM dye showed the best photovoltaic performance among MM and DN dyes: maximum monochromatic incident photon-to-current conversion efficiency (IPCE) of 98 %, short circuit current (JSC) of 4.58 mA/cm2, open circuit voltage (VOC) of... 

Carbazole is an alternant polycyclic aromatic hydrocarbon consisting of three fused rings with a large, aromatic system, containing nitrogen atom showing extensive electron delocalization. In this work, carbazole applied as π-conjugated bridge to construct electron donor–π–electron acceptor (D–π–A) organic dyes, where barbutiric acid and thiazolidine-2,4-dione as electron acceptor. The effects of these three acceptors and length of alkyl on the performance of the DSSCs were investigated systematically along with their photophysical and photo electrochemical properties. These series of organic dyes include (B-CH, B-C B, DT-CB, DB-CB). Our investigation indicate among dyes containing butyl as... 

In this research, inorganic copper thiocyanate (CuSCN) hole transport layer (HTL) was applied in conventional structure of perovskite solar cells (PSCs). Besides, mixed halides perovskite (Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3) was utilized as the light absorbing layer and deposited on FTO/compact TiO2 substrates through a one-step coating method in ambient condition. The mentioned perovskite is more stable against high temperature, high irradiation and humidity compared to commonly applied MAPbI3 perovskite. Nevertheless, the CuSCN could not be well dissolved in usual dipropyl sulfide solution and should be deposited for several times to achieve suitable thickness, this could reduce the... 

Ion-exchange membrane-based reverse electrodialysis (RED) shows great potential for harvesting osmotic energy from seawater and converting it to electricity. However, their low energy conversion efficiency and huge ionic resistance hinder their application on large scales. The implementation of nanofluidic channels in RED devices can significantly improve the performance of osmotic power generators due to their selective and fast ion transport. However, technical challenges in scalable processing at the nanoscale and ion-selective membranes restrict their development in economically viable generators. Here, we report fibrous-based channels as positively and negatively charged MXene fibers... 

The monolithic catalytic converter still is the main pollution control device for modern vehicles in order to reach the ever-increasing legislative demands for low emission standards. The catalytic converters require a large expansion from the exhaust pipe to the front face of the monolith. Unfortunately, packaging constraints often do not permit the use of long diffusers. Hence, flow separation within the diffuser leads to a non-uniform flow distribution across the monolith. A uniform flow distribution at the inlet monolith face is favorable for the conversion efficiency as well as the durability of the catalytic converter. Therefore the main problem is to optimize the flow distribution at... 

Light scattering, porosity, surface area, and morphology of TiO2 working electrode can affect the power conversion efficiency of dye -sensitized solar cells dramatically. Here mesoporous TiO2 microbeads were tested as working electrode in dye-sensitized solar cells based on cobalt tris-bipyridine electrolyte. Power conversion efficiencies up to 6.4% were obtained with D35 dye adsorbed onto the light-scattering microbeads. Electron transport, studied using small light perturbation methods, was found to be significantly faster in the microbead films than in standard mesoporous TiO 2 films. This was attributed to the favorable assembly of nanocrystals in the microbeads, which can increase the... 

Dye-sensitized solar cells (DSCCs) in the form of mixed nanostructures containing TiO2 nanoparticles and nanowires with different weight ratios and phase compositions are reported. X-ray diffraction and field emission scanning electron microscopy analyses revealed that the synthesized TiO 2 nanoparticles had average crystallite size in the range 21-39 nm, whereas TiO2 nanowires showed diameter in the range 20-50 nm. The indirect optical band gap energy of TiO2 nanowires, anatase- and rutile-TiO2 nanoparticles was calculated to be 3.35, 3.28 and 3.17 eV, respectively. The power conversion efficiency of the solar cells changed with nanowire to nanoparticle weight ratio, reaching a maximum at a... 

A new strategy for enhancing the efficiency of TiO2 dye-sensitized solar cells (DSSCs) by design of a new double layer film doped with Cr ions, with various morphologies, is reported. X-ray diffraction and field emission scanning electron microscope (FE-SEM) analyses revealed that the synthesized nanoparticles had uniform and nanometer grains with different phase compositions and average crystallite size in the range of 10-12 nm depending upon Cr atomic percentage. UV-vis absorption showed that Cr introduction enhanced the visible light absorption of TiO2 nanoparticles by shifting the absorption onset to visible light region. Furthermore, the band gap energy of nanoparticles decreased with... 

We introduce a new third generation of solar cell structure which inserts different-sized quantum dots in the active region of a pin structure. Generating an intermediate band in the bandgap of the host material makes a good overlap with a part of solar spectrum. The effect of the recombination mechanisms on efficiency and currentvoltage characteristics of this intermediate band solar cell is calculated. We deduce that the increase in recombination lifetime of the excited carriers can improve the characteristics of this structure. This result can be a route which helps us to take the effect on solar cell characteristics into consideration  

This paper gives the design and analysis approaches for the class-E power amplifier with a shunt inductor under the nominal conditions, i.e., zero-current switching (ZCS) and zero-current derivative switching (ZCDS), with taking into account the MOSFET nonlinear output parasitic capacitance at any duty ratio. Although, the class-E ZCS/ZCDS conditions obtained high-efficiency, but the switch-current waveform affected by the slope of the voltage across the MOSFET nonlinear drain-to-source parasitic capacitance during the switch-off state, which restricted the operating frequency. On the other hand, the duty ratio is an adjustment parameter to obtain high-frequency operation. Therefore, the... 

This paper presents solid-state ligand exchange of spin-coated colloidal lead sulfide quantum dot (PbS QD) films by methylammonium iodide (MAI) and integration of them in depleted heterojunction solar (DHS) devices having an antireflecting (AR) nanocone plastic structure. Time-resolved photoluminescence measurements determine a shorter lifetime of the charge carries on a semiconductor (TiO2) electron transfer layer for the MAI-passivated QD films as compared with those with long-chain aliphatic or short thiol ligands. Consequently, the DHS device yields improved power conversion efficiency (>125%) relative to oleic-acid-passivated PbS QD films. Using anodized aluminum oxide templates, an... 

A new poly (acrylonitrile) (PAN)-based gel polymer electrolyte (GPE) is fabricated to study the effect of carbon nanotube (CNT) on dye-sensitized solar cell (DSSC) efficiency. The GPEs are examined using electrochemical impedance spectroscopy (EIS) to analyze ionic conductivity. A maximum of 4.45 mS cm−1 ionic conductivity is achieved at room temperature with incorporation of 11 wt.% CNT. Performance of DSSC is examined with a solar simulator, and the highest energy conversion efficiency of 8.87% is achieved with the addition of 11 wt.% CNT. All GPE samples are found to follow Arrhenius model with temperature-dependent ionic conductivity testing. Structural properties are also characterized... 

This paper reports on the synthesis of ZnO nanowires (NWs), as well asthe compound nanostructures of nanoparticles (NPs) and nanowires (NWs+NPs) with different coating layers of NPs on the top of NWs and their integration in dye-sensitized solar cells (DSSCs). In compound nanostructures, NWs offer direct electrical pathways for fast electron transfer, and the NPs of ZnOdispread and fill the interstices between the NWs of ZnO, offering a huge surface area for enough dye anchoring and promoting light harvesting. A significant photocurrent density of 2.64mA/cm2 and energy conversion efficiency of 1.43% was obtained with NWs-based DSSCs. The total solar-to-electric energy conversion efficiency... 

Inorganic hole-transport materials (HTMs) have been frequently applied in perovskite solar cells (PSCs) and are a promising solution to improve the poor stability of PSCs. In this study, we investigate solution-processed copper indium gallium disulfide (CIGS) nanocrystals (NCs) as a dopant-free inorganic HTM in n-i-p type PSCs. Moreover, Cs0.05(MA0.17-FA0.83)0.95Pb(I0.83Br0.17)3 mixed-halide perovskite with proper crystalline quality and long-time stability was utilized as the light-absorbing layer under ambient conditions. To optimize the cell performance and better charge extraction from the perovskite layer, the Ga concentration in the Cu(In1-XGaX)S2 composition was changed, and the X... 

A new poly (acrylonitrile) (PAN)-based gel polymer electrolyte (GPE) is fabricated to study the effect of carbon nanotube (CNT) on dye-sensitized solar cell (DSSC) efficiency. The GPEs are examined using electrochemical impedance spectroscopy (EIS) to analyze ionic conductivity. A maximum of 4.45 mS cm −1 ionic conductivity is achieved at room temperature with incorporation of 11 wt.% CNT. Performance of DSSC is examined with a solar simulator, and the highest energy conversion efficiency of 8.87% is achieved with the addition of 11 wt.% CNT. All GPE samples are found to follow Arrhenius model with temperature-dependent ionic conductivity testing. Structural properties are also characterized... 

The fabrication of efficient perovskite solar cells (PSCs) using all-vacuum processing is still challenging due to the limitations in the vacuum deposition of the hole transporting layer (HTL). Herein, inverted PSCs using copper (II) phthalocyanine (CuPC) as an ideal alternative HTL for vacuum processing are fabricated. After proper optimization, a PSC with a power conversion efficiency (PCE) of 20.3% is achieved, which is much better than the PCEs (16.8%) of devices with solution-based CuPC. As it takes a long time to dissolve CuPC in the solution-based device, the evaporation approach has better advantage in terms of fast processing. In addition, the device with the evaporated CuPC HTL... 

In terms of manufacturability, there is a high tendency to deposit light-absorbing CuInS2 films by solution processing methods like ink-based depositions. In particular, for nanoparticle inks, the synthesis of highly dispersed and stable inks, with uniformity in the deposition process, is a serious challenge. Here, we demonstrate a novel two-step low-temperature CuInS2 film deposition method in which the In2S3 is deposited first. It then partially is converted into CuInS2 through the infiltration of Cu+ ions in the In2S3 layer in a dip-coating process. The resulting films are highly uniform, with diffraction peaks indicating the formation of pure CuInS2 phase. The proper stoichiometry of...