Cu2SnSe3 Thin Films Research Articles

Numerical Investigation of High Efficiency Cu₂SnSe₃ Thin Film Solar Cell with a Suitable ZnSe Buffer Layer Using SCAPS 1D Software

As the world’s energy demand continues to grow, thin-film solar cells are poised to play an increasingly important role in meeting that demand. In this research, we have proposed and simulated a high-efficiency Cu2SnSe3- based thin film solar cell structure using a solar cell capacitance simulator (SCAPS-1D) software. The numerical performance of Cu2SnSe3 thin films solar cell with ZnO:Al as the electron transport layer (ETL), ZnSe as the buffer layer, SnS as the hole transport layer (HTL), Ag as the front and Ni as the back contact with the structure (Ag/ZnO:Al/Cu2SnSe3/SnS/Ni) has been studied. This simulation intended to investigate the effect of the ZnO:Al electron transport layer and SnS hole transport layer on the performance of the proposed solar cell. The device was optimized concerning the thickness, temperature, series and shunt resistance, donor density of the Electron transport layer, back contact metal work function, and acceptor density of the Cu2SnSe3-based thin film solar cell. The thickness of the ETL, buffer, absorber, and HTL was optimized to 0.2 μm, 0.05 μm, 1.5 μm, and 0.1 μm, respectively. The proposed cadmium-free Cu2SnSe3 thin films solar cell exhibited a conversion efficiency of 31.04%, VOC of 1.08 V, JSC of 34.11 mA/cm2, and FF of 83.84%. As a result, due to its low cost, earth-abundant, non-toxicity, and high efficiency, the suggested Cu2SnSe3-based solar cell may be an attractive candidate for thin film solar cells.

Effect of selenization temperature on the physical properties of Cu2SnSe3 thin films

Cu2SnSe3 thin films were prepared by the two-stage process (metal layers deposited by direct current-sputtering + selenization of metal layers by rapid thermal annealing). The effect of selenization temperature (350 °C–550 °C) on the physical properties of Cu2SnSe3 was investigated thoroughly. The formation of single-phase Cu2SnSe3 was confirmed by the X-ray diffraction patterns of the selenized films at 550 °C. The Raman modes at 181 cm−1 and 231 cm−1 confirmed the formation of single-phase Cu2SnSe3 at 550 °C and the presence of secondary phase identification was also investigated. The compositional and morphological analysis was investigated using energy-dispersive X-ray spectrometer and field emission scanning electron microscopy measurements, respectively. The optical properties of selenized films were measured by the ultraviolet-visible spectroscopy and the calculated results showed the bandgap values in the range 0.9–1.44 eV. The Hall Effect measurement showed that the values of carrier concentration were decreased and the resistivity was increased with increasing of selenization temperature.

The Effect of Substrate Temperature on the Microstructure and Thermoelectric Properties of Pulsed Laser Deposited Cu2SnSe3 Thin Film

The Effect of Substrate Temperature on the Microstructure and Thermoelectric Properties of Pulsed Laser Deposited Cu₂SnSe₃ Thin Film

Growth and characterization of Cu2SnS3 (CTS), Cu2SnSe3 (CTSe), and Cu2Sn(S,Se)3 (CTSSe) thin films using dip-coated Cu–Sn precursor

Ternary compounds Cu2SnS3, Cu2SnSe3 and Cu2Sn(S,Se)3 thin films used in thin film solar cell applications were prepared at the first time by such a two-stage process that includes dip-coating of Cu–Sn precursors as distinct from vacuum-based fabrication methods followed by sulfurization/selenization of prepared precursors via rapid thermal processing at 550 °C. All prepared thin films revealed Cu-poor composition. X-ray diffraction and Raman spectra of the samples showed that Cu2SnS3 and Cu2SnSe3 thin films had a monoclinic structure as a dominant phase and additionally some secondary phases such as tetragonal Cu2SnS3 and orthorhombic Cu3SnS4. However, the tetragonal and orthorhombic phases had more impact on Cu2Sn(SSe)3 thin film. Compact, dense, and small grained surface morphologies were obtained for the Cu2SnS3 and Cu2Sn(SSe)3 thin films, while the surface morphology of the Cu2SnSe3 thin film had larger grained surface morphology. The Cu2SnS3 thin film demonstrated higher transmittance (~ 65%) and two different absorption edges that indicates formation of two band gap energy. Band gap values of Cu2SnS3, Cu2Sn(SSe)3 and Cu2SnSe3 thin films were found 0.97 eV (and 1.51 eV), 1.25 eV and 0.78 eV, respectively. The lowest resistivity (2.48 × 10−1 Ω cm) and the highest carrier concentration (1.64 × 1019 cm−3) values were observed for Cu2Sn(SSe)3 thin film.

Electrochemical and Photoelectrochemical Characterization of Cu2SnSe3 Thin Films Deposited on Mo/Glass Substrates

Cu2SnSe3 (CTSe) thin films were fabricated by selenization of a Cu-Sn alloy, which was electrochemically co-deposited from a stirred citrate solution. Photoelectrical and optical properties of the obtained CTSe thin films were investigated by using only the electrochemical (we applied the cyclic voltammetry for determination the band gap of Cu2SnSe3 thin film semiconductor), photoelectrochemical and electrochemical impedance spectroscopy methods. New method is suggested, which allows to estimate the relationship between the etching time of secondary copper selenide phase and the photoelectrical properties (open circuit photopotential and photocurrent) of the CTSe thin films. The Cu2SnSe3 thin film with the best photo-response was obtained at a selenization temperature of 500°C. A significant improvement in photoelectrical behavior was observed on the CTSe thin film after 30 s of chemical etching in a 0.75 M KCN aqueous solution with the aim to remove the residual copper selenide phase. This film has a good photoelectrical and optical properties for solar cell formation: a p-type conductivity, a band gap of 0.92 eV, a carrier concentration Nα = 1.45 × 1017cm−3 and flat band potential EFB of 0.297 V vs. saturated hydrogen electrode and a photocurrent density of 0.44 mA × cm−2 at cathodic potential of −600 mV vs. saturated hydrogen electrode. A diagram of energy bands of the CTSe/electrolyte junction has been presented.

Post-growth annealing effect on the performance of Cu2SnSe3 solar cells

In this work, the effect of post-deposition annealing in selenium environment was studied on Cu2SnSe3 thin film solar cells prepared from solid solution by doctor blade method. XRD pattern confirms deposited films are of polycrystalline nature having cubic phases with (1 1 1) orientation. The crystallinity improves with the increase in annealing temperature. At high annealing temperature surface agglomeration was found which is due to the melting and re-evaporation of the components from the surface. Electrical properties like carrier mobility, conductivity also modified with the increase in annealing temperature. Maximum efficiency of 1.17% was achieved for the sample annealed at 400 °C having barrier height (ϕb), ideality factor (n) and series resistance (Rs) nearly equal to 0.71 eV, 1.5 and 69 Ω respectively.

Structural and photoelectrochemical characterization of Cu2SnSe3 thin films fabricated by electrochemical co-deposition and selenization

The Cu-Sn alloy as a precursor for Cu2SnSe3 (CTSe) thin films was electrochemically co-deposited from a modified electrolyte solution using magnetic steering. The Cu-Sn film on the Mo/glass substrate was continuous, smooth and contained no organic contaminants according to Raman spectroscopy. The current efficiency of Cu-Sn electrodeposition in the solution was about 90%, i.e. significantly higher than that previously reported. The Cu-Sn films with the Cu/Sn ratio in the range of 1.6–2.3 were selenized at temperatures of 350, 400, 450, 500 and 560 °C. The synthesized CTSe films were characterised by XRD, SEM, EDX and Raman spectroscopy. The photo-activity of the films was assessed by photoelectrochemical measurements in a 0.2 M Eu(NO3)3 aqueous solution. The conducted investigations revealed that the Cu2SnSe3 film with Cu/Sn = 1.9 selenized at a temperature of 500 °C demonstrated the best photoelectrochemical response and presented p type doping. The photo-activity of the film increased after additional annealing in air at a temperature of 200 °C. Raman spectroscopy studies of Cu2SnSe3 thin films revealed a rather insignificant difference between the spectra of cubic and monoclinic polymorphs, however, one of the bands in the low energy region could be treated as a marker of the monoclinic phase. The Raman spectra evidenced that nearly all of the studied Cu2SnSe3 films contained SnSe2 the presence of which is detrimental for the photovoltaic characteristics of both Cu2SnSe3 and Cu2ZnSnSe4.

Effect of Annealing Time on Cu2SnSe3 Thin Films Prepared by Successive Ionic Layer Adsorption and Reaction Method

Cu2SnSe3 thin films—an attractive candidate for a variety of optoelectronic and solar energy applications were prepared by successive ionic layer adsorption and reaction method and the effect of annealing time on structural, optical and electrical properties were studied. X-ray diffraction analysis revealed cubic sphalerite structure of Cu2SnSe3 thin films at 200 °C for both 1 and 2 h of annealing time. Average crystallite sizes of the Cu2SnSe3 films were found to be 39.56 and 31.65 nm for 1 and 2 h, respectively. Annealed films indicated high optical absorption co-efficient values (> 106 cm−1) in the wavelength range of 400–800 nm. However, the annealed film (1 h) showed slightly higher absorption co-efficient in comparison to 2 h and the band gap values were found to be 1.75 and 1.83 eV for 1 and 2 h annealed films, respectively. The resistivity of Cu2SnSe3 film annealed for 2 h increased (41.52 Ωm) in comparison to 1 h annealed film (25.65 Ωm). Due to the increased strain in 2 h annealed film, the dislocation density was higher and hence the optical and electrical properties of the film decreased.

High pressure Raman scattering of a co-evaporated Cu2SnSe3 thin film

We fabricated Cu2SnSe3 thin film on a Mo-coated soda-lime glass substrate by a co-evaporation method. The X-ray diffraction pattern revealed the formation of polycrystalline Cu2SnSe3 with a monoclinic structure (space group Cc). Raman scattering measurements were also performed on the thin film at a pressure ranging from 1atm to 7.01GPa. The Raman spectrum was resolved into 4 Lorentzian peaks observed at 184cm−1, 206cm−1, 236cm−1, and 252cm−1 at 1atm, which correspond to A′, A″, A″, and A′ symmetry, respectively. The effects of pressure on these Raman-active phonon modes were discussed. The measured elastic properties of Cu2SnSe3 under high pressure were also compared with those of Cu2ZnSnSe4.

Studies on structural, optical and electrical properties of electron beam evaporated Cu2SnSe3 thin films

Abstract The present work describes the deposition of semiconducting Cu2SnSe3 thin films by electron beam evaporation method. The structure of the deposited films was characterized by XRD and Raman analysis. X-ray diffraction study revealed that the Cu2SnSe3 thin films had a cubic sphalerite-like structure with crystallite size of 12 nm. Raman spectrum of the thin films confirmed the phase purity. FESEM analysis showed a continuous film with polydispersed grains of a diameter less than 1 цш and the elemental composition was confirmed by EDS spectrum. The UV-Vis spectrum revealed that the sample had high absorption in the visible region and the band gap was found to be 1.15 eV. The I-V graph exhibited the electrical resistivity and conductivity of the film as 2.13 Ω-cm and 0.468 S/cm, respectively. Thus, the electron beam evaporated Cu2SnSe3 thin films showed high purity of structure and good morphological, optical and electrical properties comparable with other methods of thin film deposition.

Thermally evaporated AgyCu2–ySnSe3 metal chalcogenide thin films and its characterization

AgyCu2–ySnSe3 thin films were prepared for four different Ag/Cu + Ag ratios (12.5%, 25%, 37.5% and 50%) by thermal vacuum evaporation technique. The XRD and HRTEM analysis assured the incorporation of Ag within the system. EDAX analysis confirmed the stoichiometric ratio of the compound. All the Ag incorporated thin films showed higher optical absorption than the Cu2SnSe3 thin film and their band gap values were found in the range of 1.93–1.63eV. The resistivity of AgyCu2–ySnSe3 thin films is much lesser than other silver based quaternary compounds such as CuAgGeSe3 and Cu0.5Ag0.5InSe2.

Structural and optical characterization of Cu2SnSe3 thin films prepared by SILAR method

Phase pure Cu2SnSe3 thin films were successfully obtained on glass substrates by annealing of successive ionic layer adsorption and reaction (SILAR) deposited thin films at 623K for an hour in selenium atmosphere. Structural, morphological, compositional, and optical properties of films were investigated, before and after annealing, via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Raman spectroscopy, and optical absorption measurements. XRD results showed that films were polycrystalline nature with cubic structure, the crystallinity was improved with annealing and the secondary phase of SnSe disappeared as well. SEM images revealed existence of the relatively big islands, which were formed overlapping large number of small grains, was observed on the surfaces. The images also showed a considerable change in the shape of the grains with annealing. EDAX measurements revealed that chemical composition of the annealed film was very close to the ideal value 2:1:3. The results of Raman measurement confirmed the formation of Cu2SnSe3 and disappearance of the secondary phase of SnSe after annealing. The optical absorption studies showed that the films have direct transitions with band gap energies of 1.38eV and 1.34eV before and after annealing, respectively.

Synthesis and characterization of Cu2SnSe3 thin films by electrodeposition route

A single phase Cu2SnSe3 polycrystalline semiconductor compound has been easily synthesized through electrodeposition technique onto conductive glass ITO substrates from an acidic solution at room temperature for the first time. The electrodeposition of CTSe films was studied using cyclic voltammetry, structural, morphological, optical, and electrical measurements. The effects of the annealing temperature on the growth of CTSe films were studied. XRD and Raman studies showed that the annealed CTSe thin films have a polycrystalline nature with a cubic crystal structure with a preferential orientation (111), and the crystalline size of the CTSe thin films increases as the annealing temperature increases. The AFM investigations show that the deposited film layer widely varies on annealing temperature. The optical band gap of CTSe alloys is inversely related to the grain size and decreases from 1.08 to 0.96 eV. Finally, the Hall effect measurements reveal that the all CTSe films are p-type semiconductors in particular a sample annealed at 300 °C exhibit a high Hall mobility 5.27 cm2/V s and low electrical resistivity 0.91 Ω cm compared to other samples.

Investigation of Mg dopant in Cu2SnSe3 thin films for photovoltaic applications

Mg-doped Cu2SnSe3 films were prepared by DC magnetron co-sputtering at room temperature for 1 h with two different targets of Cu and Sn or Cu-Mg and Sn based upon the formula of (Cu2−xMgx)SnSe3 at x = 0, 0.1, 0.2, and 0.3, abbreviated as Mg-x-Cu2SnSe3, or the [Mg]/([Cu]+[Mg]) composition ratios in the Cu-Mg target at 0, 0.05, 0.1, and 0.15, followed by a selenization procedure at 550 °C under the Se atmosphere. Mg-doped Cu2SnSe3 films were a cubic structure. The direct optical band gaps of Mg-x-CTSe films at x = 0, 0.1, 0.2, and 0.3 were estimated to be 1.19 eV, 1.18 eV, 1.19 eV, and 1.21 eV, respectively. Defect chemistry was studied by measuring structural and electrical properties of Mg-doped Cu2SnSe3 as a function of dopant concentration. Mg-x-CTSe films showed p-type at x = 0 and 0.1 and n-type at x = 0.2 and 0.3. The explanation based upon the Mg-to-Cu antisite donor defect for the change in electrical property was declared. Mg doping in controlling the electrical properties of CTSe films is fulfilled, as we did for its bulks.

Influence of Annealing Temperature on the Physical Properties of Cu2SnSe3 Thin Films Prepared by Thermal Vacuum Evaporation Technique

Influence of Annealing Temperature on the Physical Properties of Cu2SnSe3 Thin Films Prepared by Thermal Vacuum Evaporation Technique

Effect of selenization temperature on the crystalline and electrical properties of Cu2SnSe3 thin films obtained from rapid thermal process

In this paper, effect of selenization temperature on the crystalline and electrical properties of Cu2SnSe3 (CTSe) thin films obtained from rapid thermal processing (RTP) has been studied. X-ray diffraction and scanning electron microscope results indicated that the crystallinity of CTSe thin film is improved with the increase of selenization temperature. X-ray diffraction and Raman analysis revealed that the CTSe thin films without secondary phase were obtained at a growth temperature above 600 °C. A decrease of the element Tin (Sn) in the RTP process is observed as substrate temperature is increased from 550 to 700 °C. The band gap the CTSe thin films is between 0.87 and 0.91 eV distinguished by the selenization temperature. The CTSe thin films showed p-type conductivity with carrier concentrations of 1017–1021 cm−3. Hole mobility of the CTSe thin films were found to range between 4.48 and 23.6 cm2 V−1 s−1. Electrical properties improved significantly because of the RTP temperature increased.

Earth-abundant Cu2SnSe3 thin film counter electrode for high-efficiency quantum dot-sensitized solar cells

We present herein a new facile solution-phase route to the growth of high crystalline quality Cu2SnSe3 (CTSe) thin film on a conductive substrate and demonstrate for the first time its promising application as an efficient counter electrode (CE) in liquid-junction quantum dot-sensitized solar cells (QDSCs). Dissolving Cu2Se and SnSe powders in the thiol-amine mixture forms a homogeneous CTSe molecular precursor solution. High-quality crystalline CTSe thin film electrode can be readily deposited from the above solution via a low-temperature heating step. Powder X-ray diffraction experiment combined with Raman spectroscopy revealed that the resulting CTSe has the monoclinic crystal structure. Electrochemical measurements, impedance spectroscopy, Tafel polarization, and cyclic voltammetry verified that CTSe possesses fascinating electrocatalytic activity for S2−/Sn2− redox couple in aqueous polysulfide electrolyte solution, and is superior to the traditional electrocatalyst, Pt, both in catalytic activity and in electrochemical stability under prolonged potential cycling, rationalizing the improved solar cell device performance, i.e., QDSCs employing CTSe CE showed more than a two-fold improvement in power conversion efficiency relative to that of Pt-based cells. The excellent catalytic performance along with the ease of solution processing of these earth-abundant CTSe materials make them a distinctive choice among the various CEs studied.

Reduction of secondary phases in Cu2SnSe3 absorbers for solar cell application

The creation of secondary phases, such as Cu2−xSe and SnSe, and their influence on electrical properties of Cu2SnSe3 (CTSe) thin films fabricated by selenization of Cu–Sn metal precursors are investigated. The Cu2−xSe content in CTSe films is estimated via deconvolution of grazing incidence X-ray diffraction (GIXRD) patterns, and the results suggest that the Cu2−xSe content increases with the increasing Cu/Sn ratio in metal precursors. We also found that using Se and SnSe mixture powders as Se source is an effective approach to suppress the creation of Cu2−xSe secondary phase. Meanwhile, selective etching of Cu2−xSe is realized by potassium cyanide (KCN) solution. Hall measurement results reveal that the secondary phase of Cu2−xSe rather than SnSe makes major contribution to the high carrier concentration (larger than 1018cm−3) of CTSe films. The approach to further decrease the carrier concentration in CTSe films is discussed.

The aerosol assisted chemical vapour deposition of SnSe and Cu₂SnSe₃ thin films from molecular precursors.

Tin selenide (SnSe) and copper tin selenide (Cu2SnSe3) thin films have been deposited onto glass substrates by AACVD using [Sn(Ph2PSe2)2] or a mixture of [Sn(Ph2PSe2)2] and [Cu(acac)2] respectively.

Temperature induced phase transformation in coevaporated Cu2SnSe3 thin films

Cu2SnSe3 (CTSe) thin films were prepared by coevaporation at different substrate temperatures (325–400°C). The dependence of the phase transformation of CTSe thin films on the substrate temperature was investigated by X-ray diffraction and transmission electron microscopy analyses. The CTSe films grown at low temperatures (≤350°C) crystallized in the monoclinic phase and showed a strong preferential orientation of the (002) plane. The films grown at higher substrate temperatures (≥375°C) were randomly oriented with a cubic structure. A slight increase in the optical band gap from 0.84eV to 0.91eV was observed as substrate temperature was increased from 325°C to 400°C.