Usman Habib

The interfacial charge dynamics at the absorber/electron transport layer (ETL) interface critically influence the performance of perovskite solar cells (PSCs). Unfavorable interfacial properties can induce improper band alignment and mid-gap defect states, leading to enhanced charge-carrier recombination and reduced device efficiency. In this study, we employed SCAPS-1D to simulate a dual-electron transport layer (SnS ₂ /WS ₂ ) integrated with a lead-free inorganic Ba ₃ NCl ₃ absorber. The SnS ₂ /WS ₂ bi-ETL promoted a spike-like band alignment with a small positive conduction band offset and favorable band bending at the WS ₂ /Ba ₃ NCl ₃ interface, effectively suppressing interfacial recombination and improving charge extraction. Device optimization was performed by systematically varying absorber and ETL thicknesses, as well as acceptor concentration (N _a ) and defect density in the absorber. The optimized configuration, featuring a 1.1 μm absorber thickness, N _A of 10 ¹⁷ cm ⁻³ , and defect density of 10 ¹² cm ⁻³ , yielded a maximum power conversion efficiency (PCE) of 33.4%, with J _sc of 38.37 mA·cm ⁻² , V _oc of 1.02 V, and a fill factor of 85%. Furthermore, the effects of operating temperature (300–500 K) and absorber thickness on device performance and quantum efficiency were analyzed. These findings provide valuable insight into key parameters governing high-performance Ba ₃ NCl ₃ heterojunction solar cells.

Lead-free tin (Sn)-based perovskite solar cells (PSCs) have emerged as a promising alternative to conventional lead counterparts due to their lower toxicity and biocompatibility. This study presents a detailed investigation of CH ₃ NH ₃ SnI ₃ -based PSCs, focusing on interfacial energy-band alignment to improve charge extraction and limit carrier recombination. A comparative evaluation of oxide-based electron transport layers (TiO ₂ , ZnO, SnO ₂ , CeO ₂ , and Nb ₂ O ₅ ) was carried out using SCAPS-1D to determine the most suitable configuration. The optimized device, Ag/FTO/TiO ₂ /CH ₃ NH ₃ SnI ₃ /N-doped-TiO ₂ /Au, integrates an undoped TiO ₂ as the electron transport layer and N-doped TiO ₂ as a hole transport layer. With an absorber thickness of 900 nm, an acceptor concentration of 1 × 10 ¹⁵ cm ⁻³ , and a defect density of 1 × 10 ¹² cm ⁻³ , the device achieves a power conversion efficiency of 31.7% with an open-circuit voltage of 1.05 V, a short-circuit current density of 34.67 mA cm ⁻² , and a fill factor of 87%. The favorable interfacial band structure and reduced charge-trapping losses contribute to the improved photovoltaic performance. The proposed configuration underscores the potential of tin-based perovskites for achieving high-efficiency, low-cost, and sustainable photovoltaic technologies.

This paper introduces a hybrid framework for deep learning—based channel estimation tailored to free‐space optical (FSO) and FSO‐based low Earth orbit (LEO) OFDM systems. Unlike prior STA–DL approaches, the proposed method explicitly addresses two key challenges: atmospheric turbulence in terrestrial FSO links and Doppler‐induced carrier‐frequency offset (CFO) in high‐mobility LEO channels. The framework integrates spectral temporal averaging (STA) with three deep learning architectures—a feed‐forward neural network (STA‐FNN), a super‐resolution convolutional neural network (STA‐SRCNN), and a denoising convolutional neural network (STA‐DNCNN)—in a two‐stage process where STA supplies a coarse, noise‐resilient estimate that is refined by the deep network to capture nonlinear distortions and rapid channel variations. A pilot tone–based CFO synchronization module, incorporated ahead of the DL stage, provides explicit Doppler mitigation, a critical feature rarely combined with learning‐based estimators. Extensive simulations demonstrate that STA‐SRCNN and STA‐DNCNN achieve state‐of‐the‐art performance, delivering NMSE of , BER of , and EVM of 8% for 64‐QAM at 11 dB SNR in terrestrial FSO channels, while maintaining similar robust performance in LEO scenarios, as compared to conventional LS and STA. These results confirm that the proposed hybrid STA‐DL framework offers a computationally efficient and practically deployable solution that outperforms classical least‐squares and MMSE estimators for next‐generation high‐throughput optical satellite communications.

Battery thermal management is a critical factor in ensuring the performance, safety, and longevity of electric vehicle (EV) battery packs. This study investigates the effectiveness of a forced air convection cooling system, optimized cell spacing and suitable configuration in maintaining optimal battery cell temperatures. A 3D computational model was developed to analyze the temperature distribution of a battery pack under varying airflow velocities, cell spacings and configurations. The numerical simulations were validated through experimental testing, demonstrating a strong correlation between simulated and measured results. The findings reveal that with a 2 m/s velocity of the fan, the battery’s maximum temperature is reduced by 7% compared to the case of natural convection, while the fan consumed only 4% of the battery pack available capacity. An AI algorithm was trained on the experimental data obtained to perform data-driven predictions of failures. The results provide valuable insights for optimizing air cooling systems in EV applications. Future work will explore the effect of non-uniform air flow distribution in reducing the risk of thermal runaway and avoiding hot spots in the battery pack for optimal performance.

We numerically investigate and optimize the performance of GaInSb/AlGaInSb multi-quantum well (MQW) light-emitting diodes (LEDs) for mid-infrared applications. The proposed p-i-n structure addresses the challenges in carrier confinement by employing AlInSb and AlGaInSb layers, significantly reducing carrier leakage and non-radiative recombination. Our design achieves an internal quantum efficiency (IQE) of 3.5% for emission at 4.2 µm at room temperature, with an efficiency droop reduction from 92% to 88% and an injection efficiency droop from 50% to 5%. These improvements result in a 12% increase in emission intensity. This study highlights the potential of GaInSb/AlGaInSb LEDs as highly efficient mid-infrared emitters for applications such as gas sensing and industrial process monitoring.

This work employed composition-graded quantum wells (QWs) to increase the performance of red laser diodes (LDs) based on Aluminum gallium indium phosphide (AlGaInP). Two LDs, one with conventional QWs and other with composition-graded QWs, were studied numerically. The findings showed that the LD with composition-graded QWs significantly improved the device performance such as enhanced carrier concentration in the active region, decreased carrier leakage, improved carrier injection efficiency, and a higher rate of stimulated recombination rate. According to the results of the simulation, grading the QWs enhanced the slope efficiency to 0.80 W A⁻¹ and successfully reduced the threshold current to 300 mA. This enhanced performance, compared to conventional LDs, demonstrates the promising impact of our employed composition grading.

Backhaul networking is the highlighted objective of today telecommunication structure. Additionally, the backhaul networking can be possible easily utilizing optical fiber networks (OFNs). This paper studies 4 × 100 Gbps framework of long haul capacity wavelength division multiplexing (WDM) system, taking into account the impairments of nonlinearities, amplified spontaneous emission (ASE) fiber dispersion. Digital signal processing based receiver is proposed to maintain performance of OFNs in presence of nonlinear issues. The complete procedure of proposed WDM based OFNs is verified theoretically. The simulation analysis proved the validation of presented model against nonlinear impairments and provides 2.1 bit error rate (BER) at 25 and 50 GHz channel spacing, 90 μm² effective area and 500 km transmission length.

This article presents a broadband optical nano-antenna, which covers a broader range of optical communication wavelengths (666 to 6000 nm), used in nano-photonic applications. The proposed design is modeled and analyzed to obtain a satisfactory gain of up to 11.4 dBi for a single element-based antenna. The unique feature of the proposed antenna is the hybrid plasmonic waveguide-based feed, which receives the optical signal from the planar waveguide and redirects the signal out of the plane. The proposed antenna provides highly directional radiation properties, which makes it a suitable candidate for inter- and intra-chip optical communications and sensing applications. Moreover, an extension of the work is performed for an array configuration of the order 2 × 1 and 64 × 1, to increase the gain and directionality. Therefore, this shows that it can be equally useful for optical energy harvesting applications with a significant gain up to 26.8 dBi.