Double Buffer Layers Research Articles

Impact of graded CIGS absorber layer on Cd-free CIGS thin-film solar cell performance: numerical optimization

Abstract This paper investigates replacing the CdS buffer layer with (Zn, Mg)O and Zn(S, O) double buffer layers. To increase the efficiency of the structure, our strategy involves numerically studying and comparing three types of CIGS bandgap absorber layers: FB (Flat Band), Double Gradient Bandgap (DG) with a high bandgap near the Mo contact (back side), a low bandgap near the buffer layer (front side), and a minimum bandgap between them, and Simple Gradient Bandgap (SG) with a high bandgap near the Mo contact (back side) and a low bandgap near the buffer layer (front side). Each type features different linear graded profiles in the thickness direction to determine the optimal bandgap gradient of the CIGS layer. The performance of the three types is numerically analyzed using the SCAPS-1D simulator. Simulation enables us to test multiple structural combinations efficiently, saving both time and money, while providing results that guide experimental research. The proposed device structure is composed of the following layers: ZnO:Al/n-Zn1-xMgxO/n- ZnSxO1-x/p- Graded-CuIn1-xGaxSe2 /Mo. To study the effects of linear bandgap gradient distribution of Ga⁄((Ga+In) ) ratio according to the thickness direction on CIGS solar cell performance, the electrical properties of the proposed CIGS model were initially matched with experimental data to confirm the structure's accuracy. It was found that the Double Gradient Bandgap (DG), with maxima of 1.44 eV at the back side (near Mo contact), 1.238 eV at the front side (near n-type buffer layer interface), and a minimum of 1.154 eV at a position of 1.7 µm from the back side, has a higher efficiency than the other structures with 26.22% (Voc = 0.8134 V, Jsc = 37.82 mA/cm², FF = 85.21%). Optimizing the bandgap gradient of the CIGS absorber layer helps improve the efficiency of CIGS solar cells. 

Comprehensive study on epitaxial growth of GeSn(111) layers with high Sn content on Si(111) featuring Ge buffer layer

The study comprehensively discussed the crystalline properties of GeSn(111) epitaxial layers on Si(111) using Ge double buffer layers toward the formation of the direct transition GeSn(111) with a Sn content around 10%. We found that the introduction of Ge double buffer layers is rather effective to improve the crystallinity of GeSn(111) than the single buffer case. However, thicker Ge buffer layer degrades the crystallinity of GeSn(111) because the strain relaxation of GeSn layer is likely to occur. In this study, through optimizing the thicknesses of Ge buffer layers formed at low and high temperatures (LT-Ge and HT-Ge, respectively), it was clarified that 100 and 500 nm for LT- and HT-Ge thicknesses, respectively, are suited to realize a high quality GeSn(111). The grown GeSn(111) epitaxial layer includes a Sn content of ~8–11% with a compressive strain of ~1–2%, which is contained within the region of direct transition GeSn(111).

Amorphous titanium dioxide and polyaniline dual modifying silicon for highly enhanced lithium-ion storage

Silicon (Si) anode material is promising in the next generation of lithium-ion batteries (LIBs) with high energy densities for its much higher capacity (4200 mAh/g) than that of commercial graphite (372 mAh/g). However, silicon anode material with low electronic conductivity suffers a huge volume variation and accompanies side reactions during alloyed and de-alloyed process. Here, we design an inner amorphous titanium dioxide (TiO2) and an outer flexible conductive polyaniline (PANI) network dual modified Si@TiO2@PANI material for LIBs, where the TiO2 avoids the side reactions and the PANI network layer buffers the volume expansion and increases the electronic conductivity. The as-prepared Si@TiO2@PANI exhibits a high initial discharge capacity of 3050 mAh/g and maintains 1583 mAh/g after 200 cycles at 0.5 A/g. It even delivers the discharge capacity of 1002 mAh/g after 600 cycles at 1 A/g, as well as an excellent rate ability with discharge capacity of 1890, 1260 and 432 mAh/g at the high current density of 1, 2 and 5 A/g, respectively. Our strategy shows that the innovative design of double buffer layers on Si can synergistically promote stability and accelerate kinetics of Li+ transport, offering novel resolution strategy to enhance the performance of Si-based anodes for LIBs.

Single-event burnout resilient design of 4H-SiC MOSFETs through staircase-like buffer layer

With the rapid development of SiC materials, high-power devices such as SiC MOSFETs have been widely used in aerospace, new energy, nuclear applications, and other fields. This places higher demands on their reliability, especially about radiation effects. This paper proposes a 4H-SiC staircase-like buffer layer MOSFET (SBL-MOSFET) with a hardened structure against single-event burnout (SEB). A comparison is made with conventional VD-MOSFET, gauss buffer layer MOSFET (GBL-MOSFET), and double buffer layer MOSFET (DBL-MOSFET) through TCAD simulations. The performance of the SBL-MOSFET against single-event burnout is studied by investigating the electric field distribution, impact ionization rate, hole concentration, and lattice temperature. The simulation results demonstrate that the staircase-like buffer layer structure effectively improves the distribution of high electric field, reduces the impact ionization rate, and thus increases the SEB threshold voltage compared to other structures. The proposed SBL-MOSFET exhibits a 67.5 % improvement in single-event burnout threshold voltage compared to the conventional VD-MOSFET, with slight degradation of breakdown voltage and leakage current. Meanwhile, there is no significant change in other electrical parameters.

Controlled Crystallinity of a Sn-Doped α-Ga2O3 Epilayer Using Rapidly Annealed Double Buffer Layers.

Double buffer layers composed of (AlxGa1-x)2O3/Ga2O3 structures were employed to grow a Sn-doped α-Ga2O3 epitaxial thin film on a sapphire substrate using mist chemical vapor deposition. The insertion of double buffer layers improved the crystal quality of the upper-grown Sn-doped α-Ga2O3 thin films by blocking dislocation generated by the substrates. Rapid thermal annealing was conducted for the double buffer layers at phase transition temperatures of 700-800 °C. The slight mixing of κ and β phases further improved the crystallinity of the grown Sn-Ga2O3 thin film through local lateral overgrowth. The electron mobility of the Sn-Ga2O3 thin films was also significantly improved due to the smoothened interface and the diffusion of Al. Therefore, rapid thermal annealing with the double buffer layer proved advantageous in achieving strong electrical properties for Ga2O3 semiconductor devices within a shorter processing time.

Sublayer-Enhanced Growth of Highly Ordered Mn5Ge3 Thin Film on Si(111)

Mn5Ge3 epitaxial thin films previously grown mainly on Ge substrate have been synthesized on Si(111) using the co-deposition of Mn and Ge at a temperature of 390 °C. RMS roughness decreases by almost a factor of two in the transition from a completely polycrystalline to a highly ordered growth mode. This mode has been stabilized by changing the ratio of the Mn and Ge evaporation rate from the stoichiometric in the buffer layer. Highly ordered Mn5Ge3 film has two azimuthal crystallite orientations, namely Mn5Ge3 (001) [1-10] and Mn5Ge3 (001) [010] matching Si(111)[-110]. Lattice parameters derived a (7.112(1) Å) and c (5.027(1) Å) are close to the bulk values. Considering all structural data, we proposed a double buffer layer model suggesting that all layers have identical crystal structure with P6₃/mcm symmetry similar to Mn5Ge3, but orientation and level of Si concentration are different, which eliminates 8% lattice mismatch between Si and Mn5Ge3 film. Mn5Ge3 film on Si(111) demonstrates no difference in magnetic properties compared to other reported films. TC is about 300 K, which implies no significant excess of Mn or Si doping. It means that the buffer layer not only serves as a platform for the growth of the relaxed Mn5Ge3 film, but is also a good diffusion barrier.

Atomic-layer-deposited TiO2 and SnO2 coupled with CdS as double buffer layers for HTL-free Sb2S3 thin-film solar cells

The application of double buffer layers has been proven to be a beneficial approach for the enhancement of the power conversion efficiency (PCE) of antimony sulfide (Sb2S3) thin-film solar cells (TFSCs). Recently, solution-processed SnO2/CdS, TiO2/CdS, ZnMgO/CdS, and ZnSnO/CdS electron transport layers (ETLs) have been investigated as double buffer layers for Sb2S3 TFSCs. Herein, atomic-layer-deposited (ALD) SnO2 and TiO2 ETLs were applied as a double buffer layer with CdS for Sb2S3 TFSCs. The Sb2S3 absorber was deposited using a facile hydrothermal method. The TFSC devices were fabricated based on FTO/SnO2/CdS/Sb2S3/Au or FTO/TiO2/CdS/Sb2S3/Au structure without hole transport layers (HTLs). Experimental analysis revealed the reduction of the surface roughness of ETLs and decreased unfavorable (hk0) orientation of the Sb2S3 absorber after utilizing double buffer layers. Initially, incomplete nucleation of Sb2S3 was observed on SnO2 and TiO2 ETLs, which resulted in the formation of a shunting path. Conversely, complete nucleation of Sb2S3 was observed on CdS and double buffer layers. The highest PCEs of 3.98% and 4.23% were obtained for SnO2/CdS and TiO2/CdS double-buffer-layer-based cells with improvements exceeding 1% compared with the reference CdS buffer layer. Additionally, improvements in open-circuit voltage (VOC) of the order of ∼25 mV and ∼45 mV were respectively observed for SnO2/CdS (VOC = 0.676 V) and TiO2/CdS (VOC = 0.696 V) double-buffer-layer-based devices compared with the reference CdS buffer layer (VOC = 0.648 V). The enhanced device properties are mainly attributed to the improved charge carrier collection and formation of suitable band offset at the absorber and ETLs interfaces.

Impact of ZnMnO buffer and SnMnO2 window layer on enhancing the performance of CIGSSe thin-film solar cell

A conventional copper indium gallium sulphur diselenide (CIGSSe) thin-film with double buffer layer solar cell structure of Al/MgF2/ZnO: B/ZnO/ZnMgO/CIGSSe/Mo(S, Se)/Mo is simulated. A high conductivity, low cost and minimum absorption coefficient, manganese doped zinc oxide (Zn1-xMnxO) semiconductor material as a buffer-1 layer is used instead of ZnO in the conventional solar cell. It is observed that the new proposed structure increases the efficiency by 28.80%. Smaller energy band-gap and higher absorption coefficient of ZnO: B window layer material does not absorb the short wavelength photons, thus a decrease in the external quantum efficiency (EQE) of conventional cells is observed. To overcome this, a new structure is proposed to have a wide energy band-gap. A tin-doped manganese oxide (Sn1-xMnxO2) is used as window layer material instead of ZnO: B. A new thin-film solar cell (TFSC) design is proposed where SnMnO2 as window and ZnMnO as buffer-1 is proposed, which helps in instantly absorbing the maximum blue light, reducing recombination losses, increasing efficiency and EQE. This new TFSC design provides a better efficiency of 29.40%.

Simulation and Numerical Modelling of CIGSSe-Based Solar Cells by AFORS-HET

A general equation to determine properties of penternary solar cell based on Cu (In, Ga) (Se, S) 2 (CIGSSe) with a double buffer layer ZnS/Zn0.8Mg0.2O(ZMO) were derived. Numerical analysis of a (CIGSSe) solar cell with a double buffer layer ZnS/ZMO, CdS free absorber layer, were investigated using the AFORS-HET software simulation. Taking into consideration the effect of thickness and doping concentration for the CIGSSe absorption layer, ZnS buffer layer and ZnO:B(BZO) window layer on the electron transport, short circuit current density (Jsc) and open circuit voltage (Voc); numerical simulation demonstrated that the changes in band structure characteristics occurred. The solar energy conversion efficiency is 28.34%, the filling factor is 85.59%, the open circuit voltage is 782.3 mV, the short circuit current is 42.32 mA. then we take the range of the gradient between the ratio of x and y for the absorption layer, and the best result of Voc, Jsc, FF, Eff equal (838.7 mV, 40.94 mA/cm2, 86.23%, 29.61%) respectively at x= 0, y= 0.26.

Layered Double Hydroxide‐Assisted Fabrication of Prussian Blue Membranes for Precise Molecular Sieving

AbstractPrussian Blue (PB), which was first discovered as robust blue‐colored pigment in the year 1706, has shown promising prospects in disease treatment, energy conversion, water splitting, and sensing. Relying on the uniform 3.2 Å‐sized pore channels as well as high stability in aqueous environments, in this study, we pioneered in situ preparation of polycrystalline PB membranes to justify their dye rejection and metal ion discrimination ability in aqueous environments. Among various factors, the introduction of calcined NiFe layered double hydroxide buffer layers on porous α‐Al2O3 substrates was found to play a paramount role in the formation of continuous polycrystalline PB membranes, thereby leading to excellent dye rejection efficiency (>99.0 %). Moreover, prepared PB membranes enabled discriminating different monovalent metal ions (e.g., Li+, Na+, and K+) depending on their discrepancy in Stokes diameters, showing great promise for lithium extraction from smaller‐sized metal ions.

Layered Double Hydroxide-Assisted Fabrication of Prussian Blue Membranes for Precise Molecular Sieving.

Prussian Blue (PB), which was first discovered as robust blue-colored pigment in the year 1706, has shown promising prospects in disease treatment, energy conversion, water splitting, and sensing. Relying on the uniform 3.2 Å-sized pore channels as well as high stability in aqueous environments, in this study, we pioneered in situ preparation of polycrystalline PB membranes to justify their dye rejection and metal ion discrimination ability in aqueous environments. Among various factors, the introduction of calcined NiFe layered double hydroxide buffer layers on porous α-Al2 O3 substrates was found to play a paramount role in the formation of continuous polycrystalline PB membranes, thereby leading to excellent dye rejection efficiency (>99.0 %). Moreover, prepared PB membranes enabled discriminating different monovalent metal ions (e.g., Li+ , Na+ , and K+ ) depending on their discrepancy in Stokes diameters, showing great promise for lithium extraction from smaller-sized metal ions.

Numerically investigating the AZO/Cu2O heterojunction solar cell using ZnO/CdS buffer layer

Aluminium (Al)-doped zinc oxide (ZnO)/copper oxide (AZO/Cu2O) heterojunction solar cell is analyzed by a 1-D solar cell capacitance simulator (SCAPS-1D). The influence of single (CdS) and double (ZnO and CdS) buffer layers on the performance of AZO/Cu2O heterojunction solar cells is studied. The effects of device parameters such as Cu2O acceptor and CdS donor doping concentrations, external quantum efficiency, interface states density, metal work function, absorber and buffer layer thicknesses, and working temperature on both single and double buffer layer solar cell are carried out. The optimized solar cell structure of single buffer AZO/CdS/Cu2O/Au and double buffer AZO/ZnO/CdS/Cu2O/Au results in the power conversion efficiency (PCE) of 10.47 and 10.60 %, short circuit current density (JSC) of 11.33 and 11.37 mA cm−2, open-circuit voltage (Voc) of 1.1381 and 1.1405 V and fill factor (FF) of 81.21 and 81.74 %, respectively under illumination. Our findings reveal that the PCE of AZO/Cu2O based heterojunction thin-film solar cell is enhanced through the usage of a double buffer (ZnO/CdS) layer in comparison to the single (CdS) buffer layer.

Engineering capacitive contribution in dual carbon-confined Fe3O4 nanoparticle enabling superior Li+ storage capability

Iron oxides have attracted widespread attention as lithium-ion batteries anode in virtue of abundant resources, high theoretical capacity, and environmental friendliness. However, during the process of charging and discharging, the poor conductivity and large volume expansion of iron oxides lead to the pulverization of the material as well as the rapid capacity fading, which limits further application significantly. Hence, tiny Fe3O4 nanoparticles encapsulated into double layers N-doped hollow carbon nanotubes (NHCNT/Fe3O4) are synthesized by a controllable chemical bath deposition and subsequent carbonization treatment. Benefitting from the double carbon buffer layers and the outstanding N-doped carbon conductive network, the well-designed NHCNT/Fe3O4 electrode delivers an excellent cycling stability with 87% capacity retention at 1 A g−1 after 1000 cycles and a remarkable rate performance. And hollow N-doped carbon nanotubes (NHCNT) displays a favorable reversible capacity of 350 mAh g−1 in the 500th cycle at 1 A g−1. The in-depth kinetic analysis reveals the dominated capacitive contribution facilitate to realize a superior rate capability of NHCNT/Fe3O4 anode. The excellent electrochemical performance exhibited by the NHCNT/Fe3O4 composites material provides great innovative ideas and inspiration for the design of the next-generation lithium-ion battery anode materials.

Improving the Efficiency of SnS Thin Film Solar Cells by Adjusting the Mg/(Mg+Zn) Ratio of Secondary Buffer Layer ZnMgO Thin Film

In the recent years, thin film solar cells (TFSCs) have emerged as a viable replacement for crystalline silicon solar cells and offer a variety of choices, particularly in terms of synthesis processes and substrates (rigid or flexible, metal or insulator). Among the thin-film absorber materials, SnS has great potential for the manufacturing of low-cost TFSCs due to its suitable optical and electrical properties, non-toxic nature, and earth abundancy. However, the efficiency of SnS-based solar cells is found to be in the range of 1 ~ 4 % and remains far below those of CdTe-, CIGS-, and CZTSSe-based TFSCs. Aside from the improvement in the physical properties of absorber layer, enormous efforts have been focused on the development of suitable buffer layer for SnS-based solar cells. Herein, we investigate the device performance of SnS-based TFSCs by introducing double buffer layers, in which CdS is applied as first buffer layer and ZnMgO films is employed as second buffer layer. The effect of the composition ratio (Mg/(Mg+Zn)) of RF sputtered ZnMgO films on the device performance is studied. The structural and optical properties of ZnMgO films with various Mg/(Mg+Zn) ratios are also analyzed systemically. The fabricated SnS-based TFSCs with device structure of SLG/Mo/SnS/CdS/ZnMgO/AZO/Al exhibit a highest cell efficiency of 1.84 % along with open-circuit voltage of 0.302 V, short-circuit current density of 13.55 mA cm−2, and fill factor of 0.45 with an optimum Mg/(Mg + Zn) ratio of 0.02.

Increasing Optical Efficiency in the Telecommunication Bands of Strain-Engineered Ga(As,Bi) Alloys

The search for semiconducting materials with improved optical properties relies on the possibility to manipulate the semiconductors band structure by using quantum confinement, strain effects, and by the addition of diluted amounts of impurity elements such as $\mathrm{Bi}$. In this study, we explore the possibility to engineer the structural and physical properties of the $\mathrm{Ga}(\mathrm{As},\mathrm{Bi})$ alloy by employing different stress conditions in its epitaxial growth. Films with variable concentration of $\mathrm{Bi}$ are grown by molecular beam epitaxy on bare $\mathrm{Ga}\mathrm{As}(001)$ crystals and on partially relaxed $(\mathrm{In},\mathrm{Ga})\mathrm{As}$ double buffer layers acting as stressors aiming to control the $\mathrm{Bi}$ incorporation into the alloy and improving the optical properties in terms of efficiency. A combination of several structural and electronic characterization techniques and dedicated density-functional-theory calculations allows us a systematic comparison between the samples grown under compressive and tensile strain. We demonstrate the possibility to grow $\mathrm{Ga}(\mathrm{As},\mathrm{Bi})$ under different strain conditions without affecting its crystal quality. The different strain conditions strongly impact the $\mathrm{Bi}$ incorporation in the $\mathrm{Ga}\mathrm{As}$ matrix and the luminescence properties of the sample. We find (i) a striking improvement of the photoluminescence with a strongly increased radiative efficiency when $\mathrm{Ga}(\mathrm{As},\mathrm{Bi})$ is grown under tensile strain and (ii) an interesting higher redshift with respect to $\mathrm{Ga}(\mathrm{As},\mathrm{Bi})$ grown compressively on $\mathrm{Ga}\mathrm{As}$. These two effects allow us to reach the important photoluminescence emission at 1.3 \textmu{}m with a $\mathrm{Bi}$ concentration as low as 4.9% compared to 7.5% needed for samples grown directly on $\mathrm{Ga}\mathrm{As}$. This is a significant achievement for the application of the $\mathrm{Ga}(\mathrm{As},\mathrm{Bi})$ material in optoelectronic devices.

Towards high efficiency Cd-Free Sb2Se3 solar cells by the band alignment optimization

In this paper, we investigated the effect of Zn1-yMgyO/ZnO1-xSx double buffer layers on the antimony selenide (Sb2Se3) solar cells performance. Our results show that the magnesium and sulfur concentrations in proposed double buffer layers have a significant effect on the band alignment optimization at the junctions. The flexibility with Zn1-yMgyO/ZnO1-xSx double buffer layers ranging from 0 to 25% magnesium and 10%–70% sulfur allows an optimal conduction band offset (CBO) for Sb2Se3 solar cells. An improved open-circuit voltage (Voc) was observed in the Sb2Se3 solar cell with Zn0.93Mg0.07O/ZnO0.4S0.6 proposed double buffer layers due to appropriate CBO values at the junction interfaces. The short-circuit current density (Jsc) values increased as the sulfur concentration in the ZnO1-xSx buffer layer increased from 0 to 0.7 (x value), which could be related to the increase in the optical band gap of the ZnO1-xSx layer. The results demonstrated that under small positive offset conditions (spike-like), the carrier recombination rate at the interface is reduced, and consequently, the Sb2Se3 solar cell performance is improved. A Sb2Se3 solar cell with the optimum CBO amount (+0.3 eV) represented a conversion efficiency of 15.46%, which exhibited a 68% enhancement in comparison to the traditional CdS/Sb2Se3 solar cell.

Chiromagnetic Properties of Semiconductor Nanorods

Chiral inorganic nanostructures whose circular dichroism can be modulated by magnetic field represent an exciting new development in nanoscience, physics, and chemistry. In a letter published in <i>Nature Nanotechnology</i>, Zhuang et al. describe a new method for nanoscale engineering of such structures taking advantage of double buffer layers on the lattice-mismatched semiconductor nanorods. This approach enables one incorporate a magnetic Fe₃O₄ nanostructures and obtain strong chiroptical activity of achiral semiconductor particles under an external magnetic field.

Double fullerene cathode buffer layers afford highly efficient and stable inverted planar perovskite solar cells

Abstract Fullerene derivatives especially [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) with strong electron-accepting abilities have been commonly implemented as indispensable cathode buffer layers (CBLs) of inverted (p-i-n) planar perovskite solar cells (iPSCs) to facilitate electron transport. However, only a single fullerene CBL is typically used in iPSC devices, resulting in interfacial energy offset between fullerene CBL and metal cathode and consequently insufficient electron transport. Herein, we synthesized a novel bis-dimethylamino-functionalized fullerene derivative (abbreviated as PCBDMAM) and applied it as an auxiliary fullerene interlayer atop of PCBM to form a PCBM/PCBDMAM double fullerene CBL, leading to dramatic enhancement of both efficiency and ambient stability of iPSC devices. Incorporation of PCBDMAM interlayer facilitates the formation of interfacial dipole layer between PCBM and Ag cathode, resulting in decrease of the work function of the Ag cathode. As a result, the CH3NH3PbI3 (MAPbI3) iPSC devices based on PCBM/PCBDMAM double fullerene CBL exhibit the highest power conversion efficiency (PCE) of 18.11%, which is drastically higher than that of the control device based on single PCBM CBL (14.21%) and represents the highest value reported for double fullerene CBL-based iPSC devices. Moreover, due to the higher hydrophobicity of PCBDMAM than PCBM, iPSC devices based on PCBM/PCBDMAM double fullerene CBL shows an enhanced ambient stability, retaining 67% of the initial PCE after storage 1440 h exposure under the ambient atmosphere without any encapsulation, whereas only 43% retaining was achieved for the control device based on single PCBM CBL.

BiFeO3-Based Flexible Ferroelectric Memristors for Neuromorphic Pattern Recognition

Flexible ferroelectric devices have been a hot-spot topic because of their potential wearable applications as nonvolatile memories and sensors. Here, high-quality (111)-oriented BiFeO3 ferroelectric films are grown on flexible mica substrates through an appropriate design of SrRuO3/BaTiO3 double buffer layers. BiFeO3 exhibits the largest polarization (saturated polarization Ps ≈ 100 μC/cm2, remnant polarization Pr ≈ 97 μC/cm2) among all the reported flexible ferroelectric films, and ferroelectric polarization is very stable in 104 bending cycles under 5 mm radius. Accordingly, the ferroelectric memristor behaviors are demonstrated with continuously tunable resistances, and thus, the functionality of spike-timing-dependent plasticity is achieved, indicating the capability of flexible BiFeO3-based memristors as solid synaptic devices. Moreover, in artificial neural network simulations based on the experimental characteristics of the memristor, a high recognition accuracy of ∼90% on handwritten digits is obtained through online supervised learning. These results highlight the potential wearable applications of flexible ferroelectric memristors for data storage and computing.

Simulation of CZTSSe single solar cells by AFORS-HET software

In this paper, this sthdy simulated photovoltaic characteristics of single heterojunction solar cell with Cu2ZnSnS4 and Cu2ZnSnSe4 absorber layer numerically using the AFORS-HET program .n-CdS/ZnO double buffer layer is used for hetrostructure interfaces with the absorber layer. The cell performance is investigated against variation of different absorption layer properties such as thickness, carrier concentration. The mixed zinc and cadmium sulphide (Cd1-X Zn X S) is hired as buffer layers and reseach of the effect its thickness. CdS was selected a buffer because it improves the interface with absorbent CZTSSe and has a lofty sending in the blue wavelength. at thickness =1 μm and acceptor concentration (Na=7.9×1015 cm-3) ,a maximum efficiency (η=11.9%) is provided with an open-circuit voltage (Voc=688mv), short-circuit current (Jsc=24.6 mA.cm-2) and fill factor (FF =70.8 of the CZTS solar cell, and Voc=(597 mv), Jsc= (41.7mA.cm-2), FF = (81.2 %) and η= (20.2%) of the CZTSe solar cell.