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In the present work, we studied the optimization of annealing temperature on the formation of Cu2ZnSnSe4 (CZTSe) thin films and its impact on the film properties. The CZTSe films were deposited on Mo/SLG substrate by the thermal evaporation method. All the elements of the compound were deposited in the stack using its pellets. After the successful deposition of the films, the composition of the as deposited film was measured, then it was proceeded further for two steps annealing. The annealing parameter is one of the crucial steps for obtaining good quality kesterite-based absorber layer. In the present work, we have utilized two-step annealing to achieve the absorber layer suitable for device fabrication. The annealing in Se atmosphere were carried out at 230 °C for 10 min in first step followed by another 10 min annealing in second step with a temperature variation from 430 to 490 °C. The final temperature was varied to investigate the influence of annealing temperature on the absorber layer (CZTSe) film properties and its optimization. The films annealed between 470 and 490 °C are showing better structural, optical, electrical and morphological properties for further processing. [ABSTRACT FROM AUTHOR]

In this work, Ag-doped Cu2ZnSnSe4 (CZTSe) thin films were deposited on FTO substrate by thermal evaporation method. The structural, morphological, optical and electrical properties of the (Cu1-xAgx)2ZnSnSe4 thin films were analyzed. The XRD analysis shows tetragonal crystal structure for CZTSe thin films, and the peak shift reveals the incorporation of the Ag into CZTSe crystal structure. Raman spectra show the presence of binary phases. SEM images show irregular shaped particles, and EDS spectra show non-stoichiometric nature. The optical spectra reveal good optical absorption in the visible region, and it is increased for Ag-doped films. Hall effect analysis shows p-type conductivity for CZTSe, whereas Ag-doped CZTSe sample provokes n-type conductivity. The result is also supported by the Mott–Schottky plots. The film x = 0.5 Ag doping concentration exhibits higher band bending in the dark which is essential for increasing Voc of the photoelectrochemical cell. The carrier concentration is found to be 1018 –1020 cm−3 for (Cu1-xAgx)2ZnSnSe4 thin films. The photoelectrochemical performance of the films was analyzed. Among the films, x = 0.5 Ag-doped film shows 3.02% photoconversion efficiency (PCE). The solar cells Glass/FTO/(Cu1−xAgx)2ZnSnSe4/Cu2ZnSnSe4/Ag were fabricated, and their PCE has been analyzed. [ABSTRACT FROM AUTHOR]

We present an optical simulation of a solar cell employing core (Si) /shell (Kesterite Cu2ZnSnS4 (CZTS) or/and Cu2ZnSnSe4 CZTSe) vertically-aligned nanowire array. The method of the simulation is rigorous coupled wave analysis. In the first stage, we studied the case where the shell is composed of only CZTS or CZTSe. A larger absorptance of CZTSe led to a larger value of the ideal short circuit current (41 mA/cm2) in the case of CZTSe solar cell than in the case of CZTS solar cell (24 mA/cm2). In the second stage, to avoid the heat losses in CZTSe solar cell without reducing the current, we proposed a shell composed of a 3 µm of CZTS in the upper part and a 6 µm of CZTSe in the lower part. The maximum ideal current value in this structure is almost twice as large as that of a planar solar cell with the same amounts of used materials. Furthermore, the variation of this maximal ideal current with the incident angle of the sunlight shows that the investigated solar cell still has good performance as long as the incident angle doesn't exceed 60°. [ABSTRACT FROM AUTHOR]

This work reports on a numerical modeling of Cu2ZnSnSe4 (CZTSe) thin film based solar cells using Solar Cell Capacitance Simulator (SCAPS). First, a conventional CZTSe/CdS/ZnO solar cell structure has been proposed and optimized. The optimal output parameters (power conversion efficiency PCE = 24.50%, short circuit current density Jsc = 47.732 mA/cm2, fill factor FF = 80.478% and open circuit voltage Voc = 0.639 V) have been obtained for ZnO, CdS and CZTSe layer thicknesses closed to 0.02 μm, 0.02 μm and 1.5 μm, respectively. Next, to improve on the conventional solar cell performance, three cell structures with different highly P-doped materials as back surface field (BSF) layers, such as P+-CZTSe, P+-Cu2O and P+-CZTS, have been proposed and optimized. In comparison to the conventional cell, devices with BSF layer have shown improvements of all the photovoltaic parameters. The CZTS/CZTSe/CdS/ZnO device has provided the highest performance (PCE = 25.83%, Jsc = 51.04 mA/cm2, FF = 78.14% and Voc = 0.646 V) for ZnO, CdS, CZTSe and P+-CZTS thicknesses closed to 0.02 μm, 0.02 μm, 1.5 μm and 0.4 µm, respectively. Additionally, the generation rate is no affected by the BSF layer; however, the recombination rate has decreased in the bulk and back surface of the CZTSe absorber. Finally, the insertion of the BSF layer has caused an increase of external quantum efficiency (EQE) up to 94.5% and a slight red shift of absorption in the long-wavelength region near the band edge. [ABSTRACT FROM AUTHOR]

One-step method for the electrodeposition of thin Cu2ZnSnSe4 (CZTSe) film onto a polyaniline/FTO/glass substrate was developed. Polyaniline film was preliminary obtained also by electrochemical deposition onto the FTO/glass substrate. The nucleation of CZTSe in the course of the film formation on the polyaniline surface was studied by chronoamperometry method. This process can be described by the instantaneous crystallization model. According to SEM data, the films consist of 25–50 nm nanocrystals which can form large crystallites. Photocurrent was established to increase up to 20 times in the CZTSe/polyaniline/FTO/glass heterojunction in comparison with the polyaniline free structure. In the heterojunction, polyaniline acts as a hole transport layer improving the charge transfer to the FTO electrode and preventing circuit shorting because of porosity of the CZTSe film. Graphical abstract [ABSTRACT FROM AUTHOR]

A CZTS/CZTSe tandem solar cell with copper zinc tin sulfide (CZTS) and copper zinc tin selenide (CZTSe) absorber layers for the top and bottom cell, respectively, is proposed. The effects of different interconnect layers such as graphene, fluorine-doped tin oxide (FTO), indium tin oxide (ITO), and a p+–n+ tunnel junction consisting of CZTS and CdS on the performance of the cell are investigated, revealing that the p+–n+ tunnel junction results in the best performance. The impact of adding a thin SnS layer under the absorber layers to reduce recombination is also examined, revealing a significant improvement in cell performance. The optimized thicknesses of the buffer and absorber layers are obtained in all cases. The maximum efficiency of 26.21% is achieved in the optimum tandem device including the SnS layer and p+–n+ tunnel junction, being much higher than results for previous structures. Finally, the effect of the absorber bandgap energy on the performance of the tandem cells is investigated. [ABSTRACT FROM AUTHOR]

A MASnI 3 -based perovskite solar cell with structure CZTSe / MASnI 3 / TiO 2 / FTO was proposed in this work. To accomplish this task, first, the effect of different kesterite and stannite CZTS , CBTS , CFTS , CMTS , CNTS , CZTSe compounds as hole transport layer HTL simulations were performed in a solar cell capacitance simulator. All simulations were performed in 1.5 G 1 sun light spectrum. From the results it was found that valance band offset of the absorber/ HTL interface affects the performance of the solar cell, and among different HTL , CZTSe is proven to be a suitable candidate for HTL. After selection of CZTSe as HTL for a MASnI 3 solar cell, device optimization was performed by analyzing the absorber and HTL thicknesses and doping concentrations on device performance. After analysis, improved functional parameters were attained with a conversion efficiency of 19.52%, short-circuit current of 29.45 mA / cm 2 open circuit voltage of 0.86 V and fill factor of 76.74%. The concept presented in this work for modeling of MASnI 3 -based devices, will categorically provide ways for the feasible fabrication of a high-efficiency solar cell. [ABSTRACT FROM AUTHOR]

In this work, quaternary chalcogenide CuZnSnSe (CZTSe) was synthesized using a mechanochemical ball milling process and its thermoelectric properties were studied by electrical resistivity, Seebeck coefficient, and thermal conductivity measurements. The synthesis process comprises three steps viz., wet ball milling of the elemental precursors, vacuum annealing, and densification by hot pressing. The purpose of this is to evaluate the feasibility of introducing wet milling in place of vacuum melting in solid state synthesis for the reaction of starting elements. We report the structural characterization and thermoelectric studies conducted on samples that were milled at 300 rpm and 500 rpm. X-ray diffraction (XRD) analysis showed the existence of multiple phases in the as-milled samples, indicating the requirement for heat treatment. Therefore, the ball milled powders were cold pressed and vacuum annealed to eliminate the secondary phases. Annealed samples were hot pressed and made into dense pellets for further investigations. In addition to XRD, energy dispersive spectroscopy (EDS) studies were performed on hot pressed samples to study the composition. XRD and EDS studies confirm CZTSe phase formation along with ZnSe secondary phase. Electrical resistivity and Seebeck coefficient measurements were done on the hot pressed samples in the temperature range 340-670 K to understand the thermoelectric behaviour. Thermal conductivity was calculated from the specific heat capacity and thermal diffusivity values. The thermoelectric figure of merit zT values for samples milled at 300 rpm and 500 rpm are ∼0.15 and ∼0.16, respectively, at 630 K, which is in good agreement with the values reported for solid state synthesized compounds. [ABSTRACT FROM AUTHOR]

The influence of the conditions of electrochemical deposition of Cu-Zn-Sn-Se precursor thin films from solutions containing lactic acid on their optical and electrophysical properties was studied. It was found that an additional annealing step of precursor films in a selenium atmosphere at 550 °C is necessary for the preparation of single-phase polycrystalline photoconducting Cu-Zn-Sn-Se films with a band gap energy equal to ~1 eV. The obtained semiconductor CZTSe materials satisfy the composition and property requirements imposed on absorbing layers in solar panels. [ABSTRACT FROM AUTHOR]

The compositional distribution of elements is known to be significant for the high conversion efficiency of CZTSe solar cells. As detailed understanding of the Cu/(Zn+Sn) ratio in the light absorption layer is important, CuZnSnSe (CZTSe) films grown via the co-evaporation process under different copper fluxes were characterized. It is difficult to evaluate the Cu content effect on the properties of CZTSe films grown using a co-evaporation process with Cu, Zn, Sn, and Se elemental effusion sources because the Cu flux variation during the process also induces other element ratio changes. Furthermore, the Zn/Sn ratio shows significant correlation to the Cu/(Zn+Sn) ratio variation in CZTSe thin films. Replacing the zinc metal effusion source with the ZnSe compound source resulted in less fluctuation in the Zn/Sn variation according to Cu flux change during the CZTSe co-evaporation. This can be useful in evaluating the effect of the different Cu ratios on the CZTSe solar cell characteristics. [ABSTRACT FROM AUTHOR]