Atowar Rahman

Tandem Solar Cells (TSCs) offer a strategic approach to surpass the efficiency limits of single-junction solar cells by harnessing complementary spectral absorption. This study explores the design and optimization of a novel TSC architecture composed entirely of Transition Metal Dichalcogenide (TMDC) materials, employing a WSe ₂ -based top cell and a MoTe ₂ -based bottom cell. The top cell leverages the tunable bandgap and superior carrier transport properties of WSe ₂ to effectively harvest high-energy photons, while the MoTe ₂ bottom cell is optimized to absorb lower-energy photons, enabling broad-spectrum solar utilization. The top cell architecture consists of an ITO/ETL/WSe ₂ /HTL configuration, in which three (3) different electron transport layers (ETLs) and four (4) hole transport layers (HTLs) are evaluated to identify the optimal photovoltaic configuration. Key performance-affecting parameters including absorber thickness, doping density, defect density, and metal work function are systematically optimized. Following comprehensive optimization, the top cell with the configuration Al/ITO/ZnO/WSe ₂ /CGSe/Ni achieves the highest performance, with a power conversion efficiency (PCE) of 33.50% . The pre-developed MoTe ₂ -based bottom cell is tailored for tandem integration using a current-matching technique to align it’s short circuit current density (J _sc ) with that of the top cell. The resulting WSe ₂ /MoTe ₂ tandem device demonstrates a power conversion efficiency of 58.73%, with a V _OC of 2.28 V, a J _SC of 32.86 mA cm ⁻² , and an FF of 78.4 % , outperforming the individual sub-cells. These theoretical results highlight the promising potential of all-TMDC tandem configurations for next-generation photovoltaic technologies.

Molybdenum telluride (MoTe₂) shows great promise as a solar absorber material for photovoltaic (PV) cells owing to its wide absorption range, adjustable bandgap, and lack of dangling bonds at the surface.

Photovoltaic solar cells (PVSC) with Molybdenum telluride (MoTe₂) have received considerable attention because of their wide range of absorption, along with the absence of dangling bonds at their surface. Here, MoTe₂-based PVSC with a preliminary device structure of Al/ITO/n-MoSe₂/p-MoTe₂/Pt was designed and estimated its performance by using the solar cell capacitance simulator in one dimension software program (SCAPS-1D). The effect of different parameters like thickness, doping density, and interface defect density of each layer was also investigated. Our investigation reveals that a moderate thickness of ∼1000 nm of MoTe₂ and 500 nm of MoSe₂, a higher concentration of more than 10¹⁷ cm⁻³ for both layers and moderate defect density of below 10¹⁴ cm⁻³ are favorable for the better PVSC device. The effect of integrating of p ⁺ -N:Cu ₂ O layer in the MoTe₂-based PVSC as a back surface field (BSF) layer was also taken into account to improve the device performance. We also evaluated the output parameters of the optimized Al/ITO /n-MoSe ₂ /p-MoTe ₂ /p ⁺ -N:Cu ₂ O/Pt PVSC with different series and shunt resistance, back-metal work function, and working temperature. Our analysis shows that minimum series resistance, higher shunt resistance, lower working temperature, and a high back-metal work function of more than 5.35 eV are advantageous for superior PVSC due to low recombination losses, low electrical losses, and better transport of charge carriers. The best performance of 28.75% with J_sc of 34.11 mA cm⁻², V_oc of 0.98 V, and FF of 86.3%, was achieved by optimizing all parameters. To further improve the device performance, the bifacial mode of optimized Al/ITO /n-MoSe ₂ /p-MoTe ₂ /p ⁺ -N:Cu ₂ O/Pt was considered and the PV performance of the proposed bifacial-PVSC has been also studied by using SCAPS-1D. Compared to the mono-facial device, a bifacial-PVSC device shows better performance with the bifacial factor of 77.5%, bifacial gain of 14.78%, and a higher PCE of 32.17%.

The ternary chalcostibite copper antimony sulfide (CuSbS₂) system, with its very high optical absorption coefficient, low-cost, vacuum-free fabrication techniques, and earth-abundant elements, is a rising candidate as solar absorber material for ultrathin film solar cells. However, due to the Schottky barrier formed at the back-contact and high carrier recombination at the CuSbS₂/CdS interface, the efficiency of conventional CuSbS₂/CdS heterojunction solar cell is very poor. This article proposes titanium dioxide (TiO₂) as an alternative to CdS layer for the CuSbS₂-based thin film solar cells (TFSCs). Using TiO₂, CuSbS₂, and Mg-doped CuAlO₂ (CuAlO₂:Mg) as an electron transport layer (ETL), absorber layer, and back-surface field (BSF) layer, respectively, a novel (Al/ITO/n-TiO₂/p-CuSbS₂/p⁺-CuAlO₂:Mg/Au)-based npp⁺ heterojunction solar cell has been designed and simulated by SCAPS-1D solar cell simulator. The effects of integrating the CuAlO₂:Mg BSF layer on the PV responses of the CuSbS₂-based heterojunction solar cell in terms of the built-in potential and the back-contact carrier recombination have been studied. In addition, an investigation on the influences of various device parameters viz. carrier concentration and thickness of each layer, back-contact metal work function, shunt and series resistance, and working temperature have been carried out systematically. The results are analyzed in correlation with the PV parameters of the device to optimize the efficiency of the proposed solar cell. The optimized CuSbS₂-based solar cell shows good performance stability at high temperature, with a maximum efficiency of 23.05% (V_oc= 969 mV, J_sc= 34.61 mA/cm², FF = 68.71%).

In recent years, organic-inorganic hybrid perovskite solar cells (PSCs) have received more and more attention due to their high photovoltaic (PV) performance, potentially high efficiency, simple cost-effective, scalable, and vacuum-free fabrication techniques. Concerned, but there are still stability issues in PSCs. The use of inorganic materials as photogenerated carrier transport layers can enhance the stability of PSC. In this report, we designed a PSC model with a novel npp⁺ heterojunction cell structure of Al/ITO/BaSnO₃ /CH₃NH₃ PbI₃ /Cu₂O/(Cu or Mo) and analyzed the structure by varying the thickness and carrier concentration of each constituent layer, working temperature, and back-contact metal work function using SCAPS-1D solar cell simulator. The simulation addresses, in particular, the role of the BaSnO₃ as electron transport materials (ETM) and Cu2O as hole transport materials (HTM) for the device performance. Using BaSnO₃ and Cu₂O as ETM and HTM, respectively, this article presents the optimization of cell parameters to improve device performance with a predicted power conversion efficiency (PCE) of 32% for the modeled PSC. The proposed novel structure for PSC showed very good PV performance stability on elevated temperature with the temperature coefficient of PCE of only - 0.112 %K^-1.

This article presents numerical investigations of the novel (Ni/SnS/Cu₂SnSe₃/TiO₂/ITO/Al) heterostructure of Cu₂SnSe₃ based solar cell using SCAPS-1D simulator. Purpose of this research is to explore the influence of SnS hole transport layer (HTL) and TiO₂ electron transport layer (ETL) on the performance of the proposed cell. Based on the proposed device architecture, effects of thickness and carrier concentration of absorber layer, SnS HTL, TiO₂ ETL, absorber layer defect density, operating temperature and back-contact metal work function (BMWF) are studied to improve the cell performance. Our initial simulation results show that if SnS HTL is not introduced, the efficiency of standard Cu₂SnSe₃ cell is 1.66%, which is well agreed with the reported experimental results in literature. However, by using SnS and TiO₂ as HTL and ETL, respectively and optimizing the cell parameters, a simulated efficiency of up to 27% can be achieved. For Cu₂SnSe₃ absorber layer, 5 × 10¹⁷ cm⁻³ and 1500 nm are the optimal values of carrier concentration and thickness, respectively. On the other hand, the BMWF is estimated to be greater than 5.2 eV for optimum cell performance. Results of this contribution can provide constructive research avenues for thin-films photovoltaic industry to fabricate cost-effective, high-efficiency and cadmium-free Cu₂SnSe₃-based solar cells.