Effect of feeding flow rate on characteristics of CuInSe2 films prepared by flash evaporation

Copper indium selenide CuInSe2 (CISe) is one of the most promising absorber materials in high efficiency heterojunction thin-film solar cells due to its high conversion efficiency and known high stability. This paper describes a simple method for preparing CuInSe2 films from pre-prepared CuInSe2 ingot powder using a flash evaporation method. The primary goal of this work is to investigate the effect of feeding flow rate on CuInSe2 film characteristics. The powder feeding flow rate into the evaporator has been adjusted to control the film growth rate. Structure, composition, morphology, electrical and optical properties have all been studied for films deposited at different feeding flow rates. The results show that varying the feeding flow rate affects film characteristics, and that lower feeding rates yield films with better characteristics, which should be considered in future semiconductor film processing

Effect of under nitrogen annealing on photo-electrochemical characteristics of films deposited from authentic Cu2SnSe3 sources by thermal vacuum under argon gas condensation

This communication describes how annealing under nitrogen affects photo-electrochemical characteristics of films deposited from authentic Cu2SnSe3 sources by vacuum evaporation under argon gas (low flow rate 5 cm3/min) using substrate 300 °C. Annealing lowered the photoresponse of the deposited film, by affecting crystallite structure, morphology, composition and pores in the films. Annealing at temperatures in the range 150–350 °C improved crystallinity of the film but lead to pore formation between adjacent, which lowered photoresponse by increased resistance across the electrode/redox interface. Higher temperature (450 °C) annealing lead to SnO2 formation, as an additional phase, at the expense of Cu2SnS3 decomposition. Porosity and mixed phases with SnO2 presumably increased film internal resistance and resulted in poor charge transfer across the solid/redox couple interface. By affecting film characteristics, annealing lowered photoresponse for the deposited films

SnSe thin film electrodes prepared by vacuum evaporation: enhancement of photoelectrochemical efficiency by argon gas condensation method

The effect of argon gas condensation (AGC) on crystallinity, surface morphology and photoelectrochemical (PEC) characteristics of SnSe thin films, prepared by thermal vacuum deposition onto ITO/glass substrates, has been investigated. The focal theme was to improve growth process of SnSe thin films and consequently enhance their PEC characteristics, by including argon gas during film manufacturing. For comparison purposes, the films grown With- and Without-AGC were characterized using various techniques such as X-ray diffractometry, UV-VIS spectroscopy, and SEM. The results indicate enhancement in film crystallinity and surface morphology by inclusion of argon gas. Such enhancement has been attributed to slower deposition rate due to argon gas presence. Photoelectrochemical property of SnSe thin film electrodes was studied using linear sweep voltammetry in dark and under illumination. The With-AGC electrodes showed higher photoactivity than the Without-AGC counterparts. Enhancement of PEC characteristics of SnSe With-AGC thin film electrodes is consistent with their crystallinity and surface uniformity. Inclusion of AGC in thermal vacuum deposition processes is potentially valuable to prepare enhanced SnSe thin film electrodes even without the need for further treatment such as etching or annealing

New technique for efficiency enhancement of film electrodes deposited by argon gas condensation from metal chalcogenide sources

This work describes a new technique to enhance photoactivity of metal chalcogenide-based semiconductor film electrodes deposited by thermal vacuum evaporation under argon gas flow. The experimental work involves controlling a number of parameters such as type of source material (SM = SnSe, Cu2SnSe3 and Cu2ZnSnSe4), substrate temperature (TS = room temperature RT, 100, 200, 300°C), argon gas flow rates (VA = 5, 10, 15, 25 cm3 /min) and temperature of annealing (TA= 150, 250, 350, 450 °C) under nitrogen atmosphere. The effects of varying each parameter on structural, morphological, compositional, photoresponse and optical properties of the deposited electrode were studied. The film deposited at TS = 100 °C under VA = 25 cm3/min from Cu2ZnSnSe4 (CTZSe) source showed highest photoactivity (p %) value 55.7 % compared to films deposited from SnSe (TSe) and Cu2SnSe3 (CTSe) sources, with p % values of 8.3 % and 34.8 %, respectively. Thus, using the quaternary Cu2ZnSnSe4 compound as a source material, offered a new inroad to prepare photoactive thin film electrodes using the argon gas condensation (AGC) technique, simply by varying argon gas flow rate

Effect of argon gas flow rate on properties of film electrodes prepared by thermal vacuum evaporation from synthesized Cu2SnSe3 source

This work describes a new technique to enhance photoresponse of metal chalcogenide-based semiconductor film electrodes deposited by thermal vacuum evaporation under argon gas flow from synthesized Cu2SnSe3 sources. SnSe formation with Cu-doped was obtained under higher argon gas flow rate (VA = 25 cm3/min). Higher value of photoresponse was observed for films deposited under VA = 25 cm3/min which was 9.1%. This finding indicates that Cu atoms inside the SnSe film were important to increase carrier concentrations that promote higher photoresponse

Effect of argon gas on photoelectrochemical characteristics of film electrodes prepared by thermal vacuum evaporation from synthesized copper zinc tin selenide

Copper Zinc Tin Selenide (CZTSe) compound was synthesized from its constituent elements in an evacuated quartz ampoule. The synthesized compound was used as source to deposit film electrodes by vacuum evaporation method under different argon gas flow rates. The argon gas flow rate affected film surface morphology and chemical composition. The film prepared under higher argon gas flow rate of 15 cm3/min or higher exhibited photoelectrochemically p-type behavior due to the SnSe compound. When using argon flow rate of 10 cm3/min or lower, the film exhibited mixed p- and n-type behaviors due to mixed CZTSe and ZnSe phases. The deposited films exhibited high absorption coefficient value (> 4.0 x 104 cm-1) in the wavelength range of 400 and 800 nm, showing their applicability as visible light energy conversion materials. The results show the potential value of the technique described here, where film electrode main characteristics can be controlled by simply changing the argon gas flow rate

Film electrodes deposited from Cu2SnSe3 source in comparison with those deposited from SnSe and Cu2ZnSnSe4 sources by thermal vacuum evaporation: effect of argon gas flow rate

Addition of argon gas, with different flow rates, to vacuum evaporation deposition of film electrodes from Cu2SnSe3 source, affect nature and properties of the resulting films. While keeping other factors constant, it is possible to control nature and properties of the resulting films simply by controlling the argon gas flow rate. This work shows that films deposited from Cu2SnSe3 under high argon gas flow rate (25 cm3/min) involved SnSe as a major compound, with low concentration of Cu dopant. The film showed higher photoresponse than those deposited from pristine SnSe source. Under lower argon gas flow rates, the resulting films were dominated by the ternary source compound itself, which also showed lower photoresponse than that deposited under higher flow rate. Structure, morphology, chemical composition, optical and photo-electrochemical characteristics have all been studied for films deposited from Cu2SnSe3 under different argon gas flow rates, in parallel with earlier films deposited from SnSe and Cu2ZnSnSe4. The films deposited from Cu2SnSe3 or Cu2ZnSnSe4 under high argon gas flow rate showed a p-type semiconductor behavior with energy gap of about 1.0 eV which confirms the existence of SnSe as a dominant component in each case. A mechanism, which is mainly based on a model of elastic collisions, is proposed to explain the production of SnSe films from the ternary and quaternary sources. On the other hand, the presence of low concentrations of Cu or/and Zn species in the resulting SnSe films is presumably responsible for enhanced photoresponse, as compared to films deposited from pristine SnSe

Membrane electrode assembly with high efficiency and stability: effect of solvent type and membrane composition

Membrane electrode assembly (MEA) method is being widely considered in proton exchange membrane fuel cell (PEMFC) preparation. This work describes for the first time how PEMFC performance can be enhanced, while using relatively low temperature processing for the MEA, by choosing the suitable solvent and suitable ionomer (nafion) content. Three dispersion solvents (water, ethylene glycol and ethanol) have been examined here, and ethanol (with lowest boiling point) showed best PEMFC performance. In addition to its non-hazardous nature, the low boiling point ethanol allowed manufacturing the working membrane at 130°C or lower besides using a safe solvent to use. In each solvent system, different nafion concentrations were used (10%, 20% and 30%). The 30% nafion concentration in ethanol showed highest performance (Open circuit potential of 0.88 V and output working potential of 0.67 V at 20 mA/cm2 current density) among the series. The anode and cathode, of the MEA, were both fabricated using same catalyst material (Platinum) and same nafion sheet thickness (50 μm). The spray method was employed. The electrochemical performance for the prepared MEA fuel cells was assessed by linear sweep voltammetry to evaluate the open circuit voltage

Deposition and characterization of SnSe and CuInSe2 thin films by thermal evaporation technique from synthesized SnSe and CuInSe2 sources

Tin selenide (SnSe) and copper indium diselenide (CuInSe2) compounds were synthesized by high temperature reaction method using combination of sealed ampoule (at relatively low pressure ~10-1 Pa without inert gas) and heating at specific temperature profile in rocking furnace. Powder X-Ray diffraction analysis showed that the products involved only single phases of SnSe and of CuInSe2 only. Using the reaction products as source materials, the SnSe and CuInSe2 thin films were vacuum-deposited on glass substrates at room temperature. Structural, elemental, surface morphological and optical properties of the as-deposited films were studied by X-Ray diffraction (XRD), energy dispersive X-Ray (EDX) analysis, field emission scanning electron microscopy (FESEM) and UV-Vis-NIR spectroscopy. Single phase of SnSe and CuInSe2 films were obtained by thermal evaporation technique from synthesized SnSe and CuInSe2 compound without further treatment