Aimin Liu

The mechanical qualities of single – and multi-layer CH₃NH₃XI₃ (X = Pb, Sn, Mn) perovskite structures have been computed using the LAMMPS programme via the molecular dynamics’ method. The LAMMPS analysis code is the keystone for computing mechanical characteristics in simulations. The stress–strain curves of the simulated atomic structures are offered for tests in the X and Y directions. The stress–strain curves were significantly computed by employing the loading technique and the deform command during the computational tests. Mechanical data was retrieved by inducing deformation in the simulated structures. The stress–strain curves for the single – (SL) and the multi-layer (ML) CH₃NH₃XI₃ at various temperature and pressure values in the X and Y directions were also produced and compared, after applying a maximum stress (ultimate strength) using a load. Molecular dynamics (MD) simulations using LAMMPS software showed that layered perovskite materials possess high flexibility compared to the non-layered perovskite materials, which is essential in perovskite solar cells. The studied atomic structures thus provided the significant mechanical properties for designing proficient perovskite solar cells via the MD simulation. GRAPHICAL ABSTRACT

Copper zinc tin sulfide (CZTS) and copper zinc tin sulfo selenide (CZTSSe) kesterite minerals are nontoxic and abundant in the earth with the promise of cost-effective photovoltaic applications. This study explains a tandem solar cell made of kesterite materials that can capture sunlight over a broad spectrum. The proposed tandem structure comprises a wide bandgap CZTS thin-film upper subcell and an underlying narrow bandgap CZTSSe-based lower subcell. The upper and lower subcells are simulated using solar cell capacitance simulator-one dimension and validated against the experimental results to determine the viability of the proposed tandem design. Additionally, the performance of both subcells is evaluated for tandem configuration by adding a back surface field layer, a modification of the back contact, testing at different thicknesses, and doping of both subcell absorber layers. As a result, optimizing both subcells improved tandem solar cell open-circuit voltage (V _oc) to a maximum of 1.5 V, which led to an efficiency of 23.99% at the current matching condition. Furthermore, how light radiation power and temperature variations impact the proposed solar cell performance is being investigated. This study provides significant insights into efficient tandem solar cell design and manufacture.

Organic–inorganic perovskites provide a favourable material system for photon and force-driven electronic systems. Lead-free methylammonium perovskite has the advantage, being an eco-friendly and simple material that can be used directly in smart and wearable electronic textile systems. However, its usage in wearables risks it being worn off and collapsing in a short time. This research assessed the resistance of lead-free methylammonium perovskite (CH₃NH₃SnI₃) to mechanical impacts by employing Large-scale Atomic/Molecular Massively Parallel Simulator molecular dynamics theories. To show the effect, stress–strain behaviour and Young’s moduli of CH₃NH₃SnI₃ were simulated by considering its molecular lattice. First, a two-axis (planar) model simulates stress and strain. Further computations were then performed to obtain the Poisson ratio, shear modulus, torsional modulus, and Pugh’s ratio. This simulation’s output renders a theoretical framework for the design and engineering of long-lasting wearable photon, and force-driven electronic and wearable devices based on CH₃NH₃SnI_3. GRAPHICAL ABSTRACT

This theoretical study looks into the mechanical and thermal behaviour of CH₃NH₃SnIxBr_3-x:PCBM. Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) and Packmol software and Molecular Dynamic Methods are applied for simulation and computation. The stress–strain profile, Young’s modulus, and the density of the lattice are studied by inserting a load in different directions. Poisson’s ratio for the PCBM doped CH₃NH₃SnIxBr_3-x was calculated via coding by Packmol software. In detail, a certain load was clamped onto the CH₃NH₃SnIxBr_3-x: PCBM lattice. Then the elongation was indicated in different directions (X, Y, Z), and the stress–strain curve and Young’s modulus were obtained. Lastly, the mechanical behaviour of CH₃NH₃SnIxBr_3-x: PCBM were studied basing on three different lattice orientations, and the assumption of bearing a specific tension at three different temperatures taken. The calculated Young’s modulus and Poisson’s ratio were very close to the experimental data previously reported, and this proved the high accuracy of this simulation work. This theoretical study therefore, profoundly addresses the current demands on extending the lifetime of perovskite and perovskite issuing devices. GRAPHICAL ABSTRACT

Multijunction or tandem solar cells can split the solar spectrum over several subcells with different bandgaps to transform the sunlight into electricity more effectively than single-junction solar cells. The monolithic tandem design of third generation silicon solar energy materials is auspicious for photovoltaics. In this paper, the Simulation-based studies of copper zinc tin sulfide/Silicon (CZTS/Si) tandem cells based on CZTS as an upper subcell and silicon as a lower subcell absorber layer have been performed using SCAPS-1D. This study aims to evaluate the CZTS tandem cells' performance based on the fact that both subcells are simulated to produce the best efficiency recorded at its bandgap. The Simulation and optimization of the single junction CZTS and Si solar cells were initially performed to fit the state-of-art records efficiency of 11.65% and 18.7%, respectively. Further, both the upper and lower cell has evaluated at different thicknesses for tandem configuration after validation. Also, to obtain the current matching condition for tandem structure, the upper subcell's performance is investigated at different thickness ranges from 0.1 µm -1 µm while keeping the lower subcell thickness at 80µm. Thus, at optimized upper absorber thickness of 0.191 µm and lower subcell 80 µm at transmitted spectrum the current matching condition obtained and gave an efficiency of 10.6% and 11.9%, respectively. The maximum efficiency of ~ 23 is obtained for tandem design with enhancing open circuit voltage 1.4 V.

Journal of Nano- and Electronic Physics. Scientific journal. ISSN: 2077-6772. Journal abbreviation: J. Nano- Electron. Phys. No page charges. All articles are freely available on-line. Issued 4 times per year. Publisher: Sumy State University. (Sumy, Ukraine)

Interdigitated back contact (IBC) n-type silicon solar cells with a different front surface layer doping concentration were fabricated and studied and the influence of the front surface doping level was analyzed via simulation (PC1D). The IBC cells were processed by industrially feasible technologies including laser ablation and screen printing; photolithography was not used. A maximum efficiency of up to 20.88% was achieved at an optimal front surface field (FSF) peak doping concentration of 4.8 × 10¹⁹ cm⁻³ with a sheet resistance of approximately 95 Ω/square, corresponding to J_sc = 40.05 mA/cm², V_oc = 671 mV and a fill factor of 77.70%. The effects of the front surface doping level were studied in detail by analyzing parameters related to carrier transmission mechanisms such as minority carrier concentration, minority carrier lifetime and the saturation current density of the FSF (J_0e). The influence of the front surface recombination velocity (FSRV) on the performance of IBC solar cells with different FSF layer doping concentrations was also investigated and was verified by examining the variation in the minority carrier density as a function of the distance from the front surface. In particular, the impact of the FSF doping concentration on the J_sc of the IBC cells was clarified by considering carrier transmission mechanisms and the charge-collection probability. The trends revealed in the simulations agreed with the corresponding experimental data obtained from the fabricated IBC solar cells. This study not only verifies that the presented simulation is a reasonable and reliable guide for choosing the optimal front surface doping concentration in industrial IBC solar cells but also provides a deeper physical understanding of the impact that front surface layer doping has on the IBC solar cell performance considering carrier transmission mechanisms and the charge-collection probability.