Photoactive nanostructure device by electrochemical processing of silicon (original) (raw)
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ECS Transactions, 2007
Oscillatory behaviour of silicon electrodes in fluoride containing solution results in formation of nanoporous oxides. Metal electrodeposition into these pores results in local Schottky junction formation. Metal nanoemitters are contacted with a transparent conductive oxide and aluminum contact fingers for preparation of the first device (Al/ZnO/Pt-SiO 2 /Si/GaIn/Ag). Present solar-toelectrical conversion efficiencies are small and various improvement possibilities are outlined.
Photovoltaic properties enhancement of solar cell based on porous silicon
Optik, 2017
Photoelectrochemical and electrochemical etching of conventional silicon solar cells of various thicknesses was conducted to the synthesis nanostructured solar cell of higher conversion efficiency. It is found that the conversion efficiency of the solar cell synthesized with the help of laser beam is higher that those etched electrochemically. The Atomic Force Microscope & Scanning Electron Microscope images imply that the pore diameter decreases from 40 μmusing 530 nm laser wavelength to 15μm when 405 nmwavelength was employed. The best hydrofluoric acid concentration to produce higher efficiency was 20 %. Image analysis has been carried out to characterize the microstructured surface using computer software.
Efficient photoelectrochemical nanoemitter solar cell
Electrochemistry Communications, 2008
Photoelectrochemical solar cells convert solar energy into electricity as fuels . The operation is based on the contact potential between a semiconductor and a redox electrolyte that results in the separation of photoinduced excess charge carriers. The applicability of photoelectrochemical solar energy conversion, however, is limited by photocorrosion at the reactive interface. Here, a new efficient photoelectrochemical solar cell is reported that avoids contact between semiconductor and electrolyte. The operational principle is based on metallic nanoemitters that form local contacts between the semiconductor absorber and the redox electrolyte while the remaining semiconductor surface is covered by an insulating anodic oxide. The nanoporous oxide, prepared by an oscillatory self-organised electrochemical process, serves as a template for spatially selective metal nanoemitter electrodeposition, resulting in a Si/SiO 2 /Pt nanocomposite structure after Pt deposition. In contact with I À =I À 3 redox electrolyte, a solar conversion efficiency of 11.2% has been obtained with the cell n À Si=SiO 2 =Pt=I À =I À 3 =C. The novel concept is characterized by the scalability of the employed oscillatory process, low-temperature processing, protection of the semiconductor surface from the solution and applicability in monolithically integrated solar fuel generating devices (photoelectrocatalysis) and solid-state solar cells.
Photoelectrochemistry ofn-silicon semiconductor in fluoride media
The effect of adding [-Ru(bpy)3] 2+ complexes during photoelectrochemical etching of n-silicon on the photocurrent generation is studied. Remarkable enhancement of photocurrent is induced due to the presence of the dye redox system. Redox stabilization of silicon via electron transfer process based on remarkable interfacial interaction between reducing species and the photoelectrode is efficiently achieved. Transient photoelectrochemical measurements during anodic dissolution of n-silicon in the presence of the complex redox ~ystem resulted in inhibition of photocurrent oscillations which was observed at high potentials in the absence of dye redox system. Practically, all photogenerated holes reaching the silicon electrode surface will be efficiently reacted with the coordination redox system resident at the electrode surface. A mechanism of current oscillations, based on periodic buildup and decay (hole/electron recombination) of space charge within the superficial oxide layer is proposed.
Electrical Characterisation of Photovoltaic Porous Si
Journal of Porous Materials, 2000
In this study n-type and p-type PV devices have been fabricated by anodising Si wafers with various resistivities in aqueous ethanoic HF solution followed by deposition of semitransparent contacts onto the porous layers. Various methods have been used for the optimisation of problematic contact to nanoporous layers. The measurements of importance are current-voltage (I-V) characteristics, the photovoltaic (PV) decay time spectrum, and the PV response as a function of excitation energy.
Electrochimica Acta, 2010
A novel electrochemical procedure for preparation of the very stable, thin modifying layer onto the n-type Si surface was elaborated. The modification consisted of platinum or/and ruthenium ultrafine particles etched into the porous Si film. A unique sequence of modifications was applied: at first the metal particles were evenly electrodeposited onto a flat silicon surface, and in the next electrochemical step the porous structure was produced. The platinum coverage and mean particle diameter were well controlled by the electrochemical programs. All the attempts and progress in modifications were monitored by scanning electron microscope (SEM) observations. Furthermore, the materials obtained were compared with the non-porous, Pt or/and Ru modified electrodes by testing them as anodes in the photoelectrochemical (PEC) cell with organic Br 2 /2Br − solution.
Photoelectrochemistry of silicon in HF solution
Journal of Solid State Electrochemistry, 2013
Photoelectrochemical, photoelectrocatalytic, and electrochemical processes of silicon anodic oxidation and hydrogen evolution in aqueous HF solution are discussed in terms of thermodynamic stability of Si, oxides SiO, SiO 2 , and Si surface hydrides. It is shown that photoelectrochemical oxidation of n-type low-resistivity silicon to SiO 2 is catalyzed by Si + photo-hole formation, whereas in the case of p-type Si, the feasibility of this reaction is predetermined by p-type conductivity. It is suggested that anodic oxidation of Si goes through the stage of SiO oxide formation and its subsequent oxidation to SiO 2. Such mechanism accounts for chemical inertness of Si phase in HF solutions as well as for selective, anisotropic, and isotropic etching of Si within E ranges from −0.5 to 0.35 V, 0.35 − 0.8 V , and E > 0.8 V, respectively. Hydrogen evolution reaction on Si surface proceeds at very large overpotential (≥ 0.5 V) through the stage of surface Si hydride formation: Si + H 2 O + e − → (SiH) surf + OH − (the rate determining step) and (SiH) surf + H 2 O + e − → Si + H 2 + OH −. Illumination-related effects of surface reactions relevant to selective and anisotropic etching and nano/microstructuring of Si surface are discussed.
International Journal of Electrochemical Science
Two electrochemical cells design (designed single tank cell and double tank cell) with three specific alcoholic solvents at constant anodization time and current density have been utilized to perform anodization in p-type silicon to prepare porous silicon nanostructures. Morphology and pore formation of porous silicon layers were characterized by Atomic Force Microscopy (AFM) and current-voltage (I-V) measurement, photoluminescence emission by ultraviolet-lamp (254-366)nm, three main types of pores could be obtained for both cells; mesopores, mesopore fill of mesopores, and macropore fill of mesopores. Single tank cell has been differentiated from double tank cell in showing stable red-orange ultraviolet photoluminescence emission increases with increasing carbon numbers in the alcohol with an improvement in current-voltage measurement.