Ahmad Nizamuddin Mustafa

The appropriate orientation of antibodies on the graphene surface is critical for the high performance of graphene biosensors. In this article, we show that a predominantly vertical orientation of antibodies to the graphene surface can be achieved by functionalizing the surface with tetrakis (4-carboxyphenyl) porphyrin (TCPP). Unlike conventional pyrene-based linkers, such as 1-pyrene butanoic acid succinimidyl ester (PBASE), which rely on a single flexible chain, the rigid porphyrin macrocycle of TCPP forms an extended π-π network with graphene and provides sites for uniform and directional antibody coupling. Applying this system to a graphene field effect transistor platform for exosome detection, we achieved 2 orders of magnitude improvement in the detection limit compared to PBASE-functionalized sensors. Computational and experimental analysis revealed that the antibody can highly exhibit vertical orientation on TCPP-functionalized graphene, while mixed orientations on PBASE-functionalized graphene confirm that the sensitivity enhancement is directly caused by the optimized orientation. The high efficiency of the TCPP method was further validated by successfully detecting pancreatic cancer exosome biomarkers in clinical samples. This biofunctionalization method could enable ultrasensitive detection of disease biomarkers on a graphene surface.

Copper(I) thiocyanate (CuSCN) is gaining attention as an effective hole transport layer (HTL) in perovskite solar cells (PSCs) due to its excellent electronic properties, high stability, and superior hole mobility. Unlike the commonly used HTL Spiro-OMeTAD, which is sensitive to moisture and degrades quickly, CuSCN offers enhanced moisture resistance and improved durability without compromising efficiency. However, its low hole concentration and conductivity limit its performance. This study investigates the doping of CuSCN with lanthanum (La) to overcome these challenges. La doping introduces additional charge carriers, significantly increasing conductivity. Using dimethyl sulfoxide (DMSO) as a solvent for solution processing, we achieved a highly transparent and stable CuSCN HTL. The optimal La doping concentration was found to be 3 mol%, yielding a conductivity of 4.13 S cm ⁻¹ and a band gap of 3.67 eV. SCAPS-1D simulation analysis was further employed to optimize the CuSCN HTL thickness, identifying 100 nm as the ideal thickness to maximize device performance. With this thickness optimization, the power conversion efficiency (PCE) improved from 28.17% for pristine CuSCN to 30.54% with 3 mol% La doping. These results demonstrate that tailored La doping combined with optimized HTL thickness can effectively enhance CuSCN’s properties, offering a promising route for developing high-performance and durable PSCs.

This study presents a comprehensive simulation analysis of 1.7 kV SiC Power MOSFETs (SiC) compared to conventional Si power MOSFETs (Si1 and Si2) focusing on thermal behavior, switching performance, and efficiency under various operating conditions. LTspice simulations over 5000 switching cycles revealed that the SiC MOSFET exhibited lower conduction losses and superior thermal stability, with higher thermal fluctuations at 50 kHz (0.32664 °C per cycle) due to prolonged on-times, while higher frequencies at 200 kHz reduced fluctuations to 0.13397 °C per cycle. Meanwhile, under the same conditions, Si MOSFETs experience higher power dissipation and poorer thermal management. Double pulse testing at varying temperatures demonstrated the SiC MOSFET has superior efficiency, peaking as high as 99.61 %, 99.55 %, and 99.44 % at 500 V, 1000 V, and 1500 V, respectively, at 150°C. A boost converter test using a 0.5 mH inductor and 200 μF capacitor further evaluated energy conversion performance, showing minimal voltage deviation in SiC MOSFETs, with outputs of 1359.32 V, 1360.57 V, and 1358.56 V at 25 °C, 100 °C, and 150 °C, respectively, compared to the theoretical 1360 V, while Si MOSFETs displayed greater voltage drops and efficiency losses. These results confirm that SiC Power MOSFETs provide significantly higher efficiency, lower thermal resistance, and superior performance in high-voltage, high-power applications compared to conventional Si MOSFETs.

The integration of graphene with other 2D materials has been extensively studied over the past decade to realize high-performance devices unattainable with single materials. Graphene-transition metal dichalcogenides (TMDCs) such as MoS₂, WS₂, MoSe₂, and WSe₂ vertical heterostructures have demonstrated promise in numerous electronic and optoelectronic applications due to the wide bandgap range and strong light–matter interaction in TMDCs, and the ability to form electrostatically tunable junctions with graphene. However, conventional methods for TMDCs growth, including chemical vapor deposition (CVD), electrodeposition, and atomic layer deposition (ALD), require high temperatures, which can degrade graphene's electrical and structural properties. Here, we investigate the impact of sulfur annealing on graphene, revealing significant etching and electrical degradation. Density functional theory (DFT) calculations identify the divacancy defect with two sulfur adatoms (DV-2S) and C–S–C bonds as the dominant defect, differing from the previously reported monovacancy with one sulfur adatom (MV-1S). This defect induces p-doping in graphene, consistent with experimental observations. To address these challenges, we introduce a protective strategy utilizing self-assembled monolayers (SAMs) during annealing, enabling the growth of high-quality WS₂ on graphene via electrodeposition. Our findings provide a foundation for integrating TMDCs with graphene while preserving its properties, advancing high-performance electronic and optoelectronic applications.

Integrating graphene and transition metal dichalcogenides (TMDs) into layered material heterostructures brings together the exciting properties that each constituent 2D material offers. However, scaling the growth of graphene-TMD and related heterostructures remains a major challenge. In this work, we demonstrate the use of electrodeposition with a single source precursor (SSP), WSeCl₄, to grow few-layer WSe₂ using graphene as an electrode. Through characterization via photoluminescence, X-ray photoelectron, and Raman spectroscopy, we show that the electrodeposited WSe₂ is stoichiometric and exhibits semiconducting and light-emitting properties. TEM imaging was also performed to show the ordering of the stacked layers of WSe₂ over graphene, demonstrating the polycrystalline structure of WSe₂. This work paves the way toward utilizing electrodeposition to stack multiple TMDs, including MoS₂, WS₂, and WSe₂ over graphene for electronic and optoelectronic applications.

The quest for optimal solar energy utilization has prompted an investigation into materials and techniques, establishing luminescent down shifting (LDS). This method converts short-wavelength photons into longer wavelengths thus expanding the range of absorption. This may further enhance the efficiency of solar cell power conversion. Herein, the Zinc Oxide (ZnO) nanoparticle is introduced as a promising candidate for LDS, mainly due to its ability to convert light effectively and cost-savvy. This research delves into enhancing Niobium (Nb) doped ZnO particles that exhibit photoluminescent characteristics to improve energy conversion efficiency. The synthesis of 1% mol of Nb-doped ZnO nanoparticles on indium tin oxide (ITO) films was achieved using a low-temperature hydrothermal technique, varying the growth duration. Extensive analysis using XRD, SEM, and UV-Vis spectroscopy revealed that the optimal outcomes were achieved with an 8-hour growing period. The analysis revealed a hexagonal wurtzite crystal structure, characterized by prominent peaks on the (111) plane and a crystallite size of 37.18 nm. A morphology study indicated that the ZnO nanorods exhibited a randomly uniform oriented arrangement and a densely formed structure measuring 0.77 ± 0.02 μm. The samples exhibited promising optoelectronic properties based on the analysis, such as a characteristic bandgap of 3.35 eV, a transmittance of 46.54%, and an absorbance of 0.33 a.u .Furthermore, the electrical conductivity of the Nb-doped ZnO films was recorded at 1.62 mΩ⁻¹cm⁻¹.These findings suggest that controlling the Nb growth offers a promising avenue for optimizing the performance of Nb:ZnO nanoparticles for advanced solar energy conversion applications.

The intriguing behavior of doped polyanilinine/graphene oxide (PANI/GO) offers a solution to the pivotal problem of device stability against moisture in perovskite solar cell (PSC). Tunable bandgap formation of doped PANI/GO with an absorber layer allows effective flexibility for charge carrier conduction and reduced series resistance further boosting the cell performance. Herein, the L₉ Orthogonal Array (OA) Taguchi-based grey relational analysis (GRA) optimization was introduced to intensify the key output responses. Furthermore, this work also delved into incorporating a Pb-free absorber perovskite layer, formamidinium tin triiodide (FASnI₃), and concomitantly eluding the environmentally hazardous substance. The numerical optimization supported by statistical analysis is based on experimental data to attain the utmost peak cell efficiency. Taguchi’s L₉ OA-based GRA predictive modeling recorded over one-fold enhancement over experimental results, reaching as high as 20.28% power conversion efficiency (PCE). Despite that, the PCE of the structures is severely affected by interface defects at the electron transport layer/absorber (ETL/Abs) vicinity, which is almost zero at merely 1 × 10¹⁴ cm⁻², manifesting that control measures need to be taken into account. This work deduces the feasibility of ETL/Abs stack structure in replacing the conventional Pb-based perovskite absorber layer, while maximizing the potential use of doped PANI/GO as a hole transport layer (HTL).

The conventional electron transport layer (ETL) TiO₂ has been widely used in perovskite solar cells (PSCs), which have produced exceptional power conversion efficiencies (PCE), allowing the technology to be highly regarded and propitious. Nevertheless, the recent high demand for energy harvesters in wearable electronics, aerospace, and building integration has led to the need for flexible solar cells. However, the conventional TiO₂ ETL layer is less preferred, where a crystallization process at a temperature as high as 450 °C is required, which degrades the plastic substrate. Zinc oxide nanorods (ZnO NRs) as a simple and low-cost fabrication material may fulfil the need as an ETL, but they still suffer from low PCE due to atomic defect vacancy. To delve into the issue, several dopants have been reviewed as an additive to passivate or substitute the Zn²⁺ vacancies, thus enhancing the charge transport mechanism. This work thereby unravels and provides a clear insight into dopant engineering in ZnO NRs ETL for PSC.

The appropriate orientation of antibodies on the graphene surface is critical for the high performance of graphene biosensors. In this paper, we show that a predominantly vertical orientation of antibodies to the graphene surface can be achieved by functionalizing the surface with tetrakis (4-carboxyphenyl) porphyrin (TCPP). We used this method to detect exosome biomarkers using a graphene field effect transistor (GFET) platform, and achieved a two orders of magnitude improvement in the detection limit of a GFET biosensor compared with that achieved by conventionally used 1-pyrene butanoic acid succinimidyl ester (PBASE). Through experimental analysis and computational simulation, we revealed that the antibody can highly exhibit vertical orientation on TCPP-functionalized graphene, while mixed orientations on PBASE-functionalized graphene. We further validated the high efficiency of TCPP method by detecting pancreatic cancer exosome biomarkers in clinical samples. This biofunctionalization method could enable the ultrasensitive detection of disease biomarkers on a graphene surface.