In order to surmount the Shockley–Queisser efficiency barrier of single-junction solar devices, tandem solar cells (TSCs) have shown a potential solution. Organic and Si materials can be promising candidates for the front and rear cells in TSCs due to their non-toxicity, cost-effectiveness, and possible complementary bandgap properties. This study researches a flexible two-terminal (2-T) organic/Si TSC through TCAD simulation. In the proposed configuration, the organic solar cell (OSC), with a photoactive optical bandgap of 1.78 eV, serves as the front cell, while the rear cell comprises a Si cell based on a thin 70 μm wafer, with a bandgap energy of 1.12 eV. The individual standalone front and bottom cells, upon calibration, demonstrate power conversion efficiencies (PCEs) of 11.11% and 22.69%, respectively. When integrated into a 2-T organic/Si monolithic TSC, the resultant tandem cell achieves a PCE of 20.03%, indicating the need for optimization of the top organic cell to beat the efficiency of the bottom Si cell. To enhance the performance of the OSC, some design ideas are presented. Firstly, the OSC is designed by omitting the organic hole transport layer (HTL). Consequently, through engineering the front contact work function, the PCE is enhanced. Moreover, the influence of varying the absorber defect density of the top cell on TSC performance is investigated. Reduced defect density led to an overall efficiency improvement of the tandem cell to 23.27%. Additionally, the effects of the variation of the absorber thicknesses of the top and rear cells on TSC performance metrics are explored. With the matching condition design, the tandem efficiency is enhanced to 27.60%, with V_OC = 1.81 V and J_SC = 19.28 mA/cm². The presented simulation results intimate that the OSC/Si tandem design can find applications in wearable electronics due to their flexibility, environmentally friendly design, and high efficiency.

In this paper, an automatic control method based on type-2 fuzzy sliding mode control for a mobile arm robot is presented. These types of robots have very complex dynamics due to the uncertainty of the arm parameters and the mobility of their base, so conventional control methods do not provide a suitable solution. The proposed method proves convergence with Lyapunov theory, and its convergence is mathematically guaranteed. A type-2 fuzzy system is responsible for approximating unmodulated dynamics, nonlinear terms, and uncertain parameters. In simulations, the performance of the proposed method with different situations, including uncertainty in arm parameters, uncertainty in mobile robot parameters (arm robot base), uncertainty in load, as well as indeterminacy in modeling have been applied. The comparison with two conventional controllers shows the efficiency and superiority of the proposed method.

This work inspects the utilization of all-polymer solar cells (APSCs) in indoor applications under LED illumination, with a focus on boosting efficiency through simulation-based design. The study employs a SCAPS TCAD device simulator to investigate the performance of APSCs under white LED illumination at 1000 lux, with a power density of 0.305 mW/cm². Initially, the simulator is validated against experimental results obtained from a fabricated cell utilizing CD1:PBN-21 as an absorber blend and PEDOT:PSS as a hole transportation layer (HTL), where the initial measured efficiency is 16.75%. The simulation study includes an examination of both inverted and conventional cell structures. In the conventional structure, where no electron transportation layer (ETL) is present, various materials are evaluated for their suitability as the HTL. NiO emerges as the most promising HTL material, demonstrating the potential to achieve an efficiency exceeding 27%. Conversely, in the inverted configuration without an HTL, the study explores different ETL materials to engineer the band alignment at the interface. Among the materials investigated, ZnS emerges as the optimal choice, recording an efficiency of approximately 33%. In order to reveal the efficiency limitations of these devices, the interface and bulk defects are concurrently investigated. The findings of this study underscore the significance of careful material selection and structural design in optimizing the performance of APSCs for indoor applications.