The most important loss mechanism in single junction solar cells is the inability to convert photons with energies below the bandgap to electricity. Due to quantum confinement, graphene-based quantum dots (QDs) provide a means to create an intermediate band (IB) in the bandgap of semiconductors to absorb sub-bandgap photons. In this work, we introduce a new type-I core/shell-graphene/Si QD for use in all Si-based intermediate band solar cells (IBSCs). Slater-Koster Tight-Binding method is exploited to compute the ground state and the band structure of the graphene/Si QD. The ground state is obtained 0.6 eV above the valance band (VB), which is suitable for creating IB between the conduction band and VB of Si. A superlattice (SL) of this QD is created and the mini-band formation in SL is investigated by varying the inter-dot spacing between QDs. A mini-band with roughly 0.3 eV bandgap is observed in the well-aligned and closely packed SL. This SL is embedded in the intrinsic region of the conventional Si-based solar cell. The mini-band in SL works as an IB in the solar cell and results in increased photon absorption. As a result, carrier generation rate improves from 1.48943×1028 m-3s-1 to 7.94192×1028 m-3s-1 and short circuit current density increases from 211.465 A/m2 to 364.19 A/m2.

The development of solar cell technology has seen the emergence of bifacial photovoltaics, which can capture sunlight from both the front and back surfaces, potentially increasing efficiency compared to traditional cells. This study investigates the effects of incorporating intermediate bands, induced by the presence of quantum wells, into a bifacial GaAs-based cell structure with an embedded InGaAs semiconductor layer to enhance energy conversion. These intermediate bands, positioned between the conduction band and the valence band levels, improve the ability of the cell to absorb sunlight over a wide range of wavelengths. The role of spectral albedo, specifically AM1.5G, paving asphalt, and construction concrete, in improving the bifacial cell performance is also examined. Using the thickness of the GaInAs layer as a key parameter, theoretical frameworks and computational simulations are employed to enhance the efficiency of this quantum well intermediate band bifacial solar cell. For an indium concentration of y=0.30, the maximum efficiency achieved is 55.86% at L=4 nm with construction concrete albedo, surpassing the efficiencies reported in previous studies.

Today, the intermediate band solar cell with quantum dots is one of the best options to achieve maximum solar energy conversion efficiency. In this paper, two solar cell models have been designed; the first reference model in with p-i-n structure, and the second model contains the InAs quantum dots implanted in the intrinsic region of the structure. By improving the structure and utilizing proper materials in the p-i-n reference cell, the efficiency increased by 34. 03%. Then, in a quantum dot-based solar cell structure, 21. 55% energy conversion efficiency improvement achieved and so that the obtained efficiency enhanced up to 55. 58% by controlling the size and position of the quantum dots. In fact, the intermediate band solar cell provides a high energy conversion efficiency that have not been reported so far.

As thermalisation loss is the dominant loss process in the quantum dot intermediate band solar cells (QD-IBSCs), it has been investigated and calculated for a QD-IBSC, where IB is created by embedding a stack of InAs(1-x) Nx QDs with a square pyramid shape in the intrinsic layer of the AlPySb(1-y) p-i-n structure. IB, which is an optically coupled but electrically isolated miniband, divides the total band gap of AlPySb(1-y) into two sub-band gaps. To obtain the thermalisation loss of AlPySb(1-y)/InAs(1-x)Nx QD-IBSCs, the position and width of IB in the band gap of AlPySb(1-y) should be calculated. The position of IB, which is equal to the first eigen-energy of a unit cell of QD, is obtained by solving the 3D Schrö dinger equation with a finite-element method and the width of IB is obtained by the absorption characteristics. Then, with the investigation of the effect of nitrogen and phosphorous molar fraction, QDs size and the distance between the QDs on the thermalisation loss, the minimized loss for the optimized structure of AlPySb(1-y)/InAs(1-x)Nx QD-IBSCs is obtained.

Introduction. Retinal detachment is a serious complication after lensectomy in traumatic cataract. It is due to traumatic retinal breaks or vitrous traction that occur after sharp and blunt trauma. Methods. Prophylactic effect of encircling band was evaluated. 247 patient"s who had undergone lensectomy due to traumatic cataract were divided in two groups. In the case group (52 patients) encircling band was used intra operatively and in the control group (195 patients) were operated on without using encircling band. Results. After follow up for at least one year, retinal detachment was not seen in any case of interventional group but was seen in 6.66 percent of the control group (P<0.05). Discussion. It is advised that this prophylactic technique be applied for traumatic cataract surgery.

Background: Amniotic band Band syndrome Syndrome (ABS) is a rare congenital anomaly which may affecting any region of the fetus. Here, we reported a case of ABS involving the upper limbs resulted in amputation, syndactyly, and lymphedema of several fingers. One of the the amputated finger was reimplanted on to the upper back of the fetus between two scapular bone. The finger-like mass had no osseous tissue.

The radar receiver protector is one of the important components in the radar system. It prevents the receiver from noise and powerful Electromagnetic wave. In this paper, the simulations are done for different structures of the radar receiver protector using COMSOL software in the X-band frequency.The simulation selected structure is based on the WR90 waveguide structure. In this simulation, parameters such as reflection and transmission coefficients, as well as the maximum field intensity created within different radar receiver protector structures, have been investigated. The studied structures include iris-diaphragms-pairs, posts-and-diaphragms, truncated-cones-and-diaphragms, Dumbell-pointed-post-tunable, Dumbell-pointed-post, and Dumbell structures.The simulation results show that the internal structure of the waveguide has an important parameter on the filtration performance, the frequency selection and intensity modes created on the tips of the electrodes. Dumbell-pointed-posts-tunable among the investigated structures due to the frequency modes and high intensity of the electric field at the tip of the electrodes, it is superior to other structures.