This work performs a quantitative comparison of different dielectric-based guided-mode resonance (D-GMR) sensors. To this end, diverse D-GMR structures are classified into three different classes, and their sensitivity (S) is compared to each other. For one of these classes in various schemes, the sensitivity is investigated for the TE and TM modes. Moreover, grating height effects are studied for different cases in this category, and analytical sensitivity equations are used as benchmarks. Then, the three classes are compared and, based on the numerical results and analytical equations, various applications are proposed for different structures in the refractive index (RI) of interest. Comparing our results to other recent works, we prove that the proposed classification leads to great sensing performances and the predictions are reliable. A comparison has been performed for methane as a gas sample (with RI of 1.0003) and a hemoglobin solution and toluene as two different analytes (with RIs of 1.33 and 1.4778, respectively). The results show a sensitivity of S = 1427.3 n m / r e f r a c t i v e index unit (nm/RIU) for methane with a detection precision of one to a few volume percentages in the air, which can also be calibrated to illuminate the fabrication variation errors. For hemoglobin, a sensitivity of 1073.4 nm/RIU is obtained, with a limit of detection of 116.15 mg/lit for 65-87 g/lit of hemoglobin in water; for the toluene sensor, S = 1019.7 n m / R I U is calculated. As a general result, a high figure of merit/sensitivity can be achieved over a wide range of applications, from gases to high RI analytes, using our proposed classifications.

In recent decades, due to advances in various industries, the use of renewable energy sources has increased significantly. Solar cells are one of the important tools in the use of renewable energies. Between the different types of solar cells, recently, perovskite solar cells, because of some advantages like low costs of materials used in their fabrication, simple manufacturing process, and high conversion efficiency, have gained the attention of many researchers. Emerging technology and recent research activities have helped perovskite solar cells to achieve high efficiency, which is highly dependent on the components and structures of the solar cell system. One way to achieve high efficiency is to use polymeric and non-polymeric materials as electron transporters (ETMs), hole transporters (HTMs), or as a stimulus to increase the performance durability of perovskite solar cells. Simulation tool is a very effective tool for designing solar cells. In this study, by using COMSOL Multiphysics software, the effect of using different hole transfer layers, both polymeric and non-polymeric, has been investigated. For this purpose, three HTM layers (Spiro-OMETAD, CuSCN, P3HT) have been investigated. The results represented that the efficiencies for these three materials were 16.8%, 15.7%, 12.1%, respectively, and Spiro-OMETAD has been more efficient.

In this work, a gas sensor based on the plasmonic double-layer graphene nanograting (GNG) structure with an enhanced figure of merit (FoM) is presented in the near-infrared region. This structure includes double periodic graphene nanoribbon arrays, separated by a dielectric. The wavelength interrogation method is employed to accurately investigate the behavior of the proposed structure for various physical and geometrical parameters, including the array pitch, graphene nanoribbon width, refractive index of the intermediate dielectric between the GNGs, and the chemical potential of the graphene. A sharp dip is achieved by the guided-mode resonance between the two GNG layers, due to their near-field coupling. For the optimized design, obtained sensitivity and FoM are 430.91 nm/RIU and 174.68 R I U − 1 , respectively, when the finite-element method is used for the simulations. The high FoM is a result of the field enhancement at the edges of the graphene nanoribbons, as well as the narrow resonance linewidth achieved by the sharp transmission dip. In addition to the high performance and FoM, the structure is robust to the misalignment of two GNG layers, offering a solution for practical gas sensing applications. To the best of our knowledge, the proposed GNG-based structure enjoys a boosted FoM compared to the previously proposed integrated gas sensors, as well as a practically feasible design for fabrication.

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Graphene and molybdenum disulfide (MoS2), as two of the most attractive two-dimensional (2D) materials, are used to improve the temperature and strain sensing responses of the few-mode fibers (FMFs). The temperature and strain effects are detected based on distributed optical fiber sensors equations, where the Brillouin scattering (BS) is investigated for the FMF tapered region. For this purpose, the 2D materials were assumed as cover layers on the tapered FMF to enhance its sensitivity. Graphene and MoS2 are used as the cover layer on the FMF cladding at a distance of 10 μm from the core, and the impact of the number of material layers is investigated. By increasing the graphene layers, the temperature and strain sensitivities increase (3% and 16%, respectively) due to the rise of the inter-modal interference of the FMF. Moreover, the increasing of the MoS2 layer number improves the temperature sensitivity by 28% but shows a lower impact on strain sensitivity (about 13%). The advantage of MoS2 with respect to graphene originates from the imaginary part of the refractive index of graphene (assumed with chemical potential of 0.4 eV at the working wavelength of 1550 nm), which leads to a lower effective index of the tapered region, hence lower sensitivities. This sensitivity enhancement can improve the performance of the BS-based sensors for local detection of the parameters under-investigation in multi-parameter sensors.