Jabir Hakami

Lead‐free quantum dot solar cells (QDSCs) have emerged as promising alternatives to conventional photovoltaics owing to their low toxicity and tunable optoelectronic properties. This study presents a comprehensive numerical investigation of AgBiS ₂ ‐ZnS‐ZnSe dual‐shell quantum dot solar cell using the SCAPS‐1D simulator. The proposed device architecture comprises ITO/WS ₂ /AgBiS ₂ ‐ZnS‐ZnSe/CuSCN/back metal, where WS ₂ and CuSCN function as the electron and hole transport layers, respectively. Various hole and electron transport materials were systematically evaluated to identify the optimum charge transport configuration. The influences of absorber thickness, acceptor concentration, bulk defect density, transport layer thickness, doping concentration, defect density, and operating temperature on device performance were thoroughly examined. The optimized absorber thickness of 0.4 µm, acceptor concentration of 10 ¹⁷ cm ⁻³ , and defect density of 10 ¹³ cm ⁻³ provided an excellent balance between light absorption and charge collection. Optimized WS ₂ and CuSCN transport layers effectively improved carrier extraction while minimizing interfacial recombination. The optimized device achieved a V _oc of 1.07 V, J _sc of 32.66 mA cm ⁻² , FF of 84.93%, and a maximum PCE of 29.95% at 300 K. Moreover, the device retained over 26% efficiency at 400 K, demonstrating excellent thermal stability and strong potential for sustainable, high‐performance lead‐free photovoltaics.

In this study, we design a new magnetic field measurement model. Specifically, we use a single two-level atom coupled to two cavities to construct a parity–time-symmetric system supporting a third-order exceptional point. If a perturbation is applied to the atomic transition frequency, the eigenvalue of the system will change, and the eigenvalue change is proportional to the cubic root of the perturbation. If the perturbation comes from the magnetic field, a sensitive magnetic field measurement device is formed. By introducing gain and loss via the input–output field, we realize a third-order EP in the non-Hermitian Hamiltonian. Our analysis shows that the system exhibits a nonlinear response to magnetic field perturbations, leading to enhanced spectral sensitivity compared to conventional linear detectors. This equivalent EP based on a cavity-QED sensing scheme breaks the limitation of passive EP sensors and provides a new theoretical idea for the design of sensitive magnetic field measurement devices.

We have systematically investigated how the strength of optical feedback (OFB) affects the dynamics, noise levels, and photon number probability density distribution (PNPDD) in time-delayed semiconductor lasers (SLs). We find that intensity noise decreases in both weak and strong OFB regimes. The shape of the PNPDDs changes based on OFB strength: it shifts from symmetric to asymmetric based on the OFB strength. In the chaotic region, the PNPDDs display a peak at low intensity and taper off at multiples of the average photon number. The results of this work suggest that operating SLs under weak or strong OFB conditions may help to minimize instability.