This work presents an improved Perovskite/u-CIGS tandem solar cell architecture, exhibiting significantly enhanced conversion efficiency and higher reliability compared to existing solutions in the literature. At the bottom cell level, traps (Dit) were identified at rear u-CIGS/Al2O3interface as a key factor degrading conversion efficiency by promoting carrier recombination. Mitigating this mechanism is essential for improving the stability and performance of solar cells. Incorporating a negative fixed charge density (Qf) in the Al2O3layer offers a promising solution, providing effective field-effect passivation to minimize minority carrier recombination at the rear surface. The proposed tandem device achieves an impressive efficiency of 23.28% using a cell pitch of 1.5 μm and silver as the back specular contact.

In this paper, we have proposed a novel deep ultra-violet (DUV) AlGaN/GaN nanowire light-emitting diode (LED) with a step-graded n-type AlInGaN electron blocking layer (EBL) instead of a conventional p-type AlGaN EBL. The nanowire is designed with Al2O3quantum dots (QDs) deposited all over the substrate. The proposed nanowire is designed for a ∼265 nm wavelength emission without affecting the hole injection efficiency. Due to enhanced carrier transport in the step-graded n-type EBL structure, there occurs reduced electron leakage into the p-region, superior hole activation and hole injection, improved output power and internal quantum efficiency (IQE). Moreover, this specially designed EBL reduces the quantum confined stark effect in the active region, ultimately enhancing the carrier wave functions overlap. The device structure is simulated using Atlas technology computer-aided design (TCAD). The efficiency is improved from ∼36.48% to ∼49.46% while switching from conventional p-type EBL to step-graded n-type EBL. Furthermore, our proposed structure exhibits 1.61% efficiency droop, which is significantly ∼4.8 times lower as compared to the regular structure.

In this paper, a field-plated III-nitride nano-HEMT over the$\beta$-Ga2O3substrate is designed with three different types of gate structures. The impact of different gate structures on transfer characteristics, drain characteristics, electric field distribution, and gate leakage characteristics of the proposed nano-HEMT are presented with profound analysis. The device with a double-head (DH) recessed gate length of$20n$m exhibits better transfer characteristics, pinch-off characteristics and lower gate leakage current. It is believed that this piece of research will give an insightful thought on the improved III-nitride HEMT grown on the emerging$\beta$-Ga2O3material as a substrate for high-power nanoelectronics applications.

The present study investigates the effect of the interface defects for ultrathin Cu (In 1-x Ga x ) Se 2 solar cells using Silvaco TCAD. The initial simulation study is carried out with the reference cell configuration in which the PV parameters fit and match the fabricated cell characteristics. Our goal is to investigate the temperature dependence of the performance of u-CIGS solar cells in the temperature range of 10–70 °C and the loss mechanism caused by interface trap density (D it ) in different cell pitch sizes on cell performance. D it defines the amount of carrier’s traps at CIGS/Al 2 O 3 interface to recombine with photogenerated carriers. The recombination mechanisms are found to play a crucial role in cell performance degradation. Further simulations quantify significant improvements in J sc and V oc for different cell pitch sizes at a fixed opening width in the Al 2 O 3 layer. Consequently, the optimum efficiency has been pointed out at a cell pitch size of 1.5 µm. MgF 2 has been used as an ARC layer to boost the efficiency up to 14 %. The results from these simulations provide insights for passivated u-CIGS solar cell optimization.