Optical and Quantum Electronics最新文献

Organic solar cells (OSCs) made of at least two electronically dissimilar molecules have attracted a lot of attention due to their low-cost solution manufacturing and color tunability. Bulk-heterojunction active layer usually achieved through spin-coating provide an appealing technique. These cells generate Frenkel excitons through photo-absorption in one molecule combined with acceptor resulting in the formation of free charge carriers that emerge after exciton dissociation at the donor–acceptor interface. These processes highly depend on optimization of the blend composition and deposition parameters such that we form an interpenetrating bi-continuous network with the domain sizes roughly twice of the exciton diffusion length. The choice of materials plays a major role in ensuring that sufficient energy offset at the donor/acceptor interface leads to an efficient charge separation. The study focused on probing a blend of poly [2-methoxy-5-(2’-ethylhexyloxy)-1, 4-phenylenevinylene (MEH-PPV) and fullerene derivatives of phenyl-C71-butyric acid methyl ester (PC₇₁BM) forming a bulk heterojunction active layer. We investigate the optical and morphological properties of MEH-PPV: PC₇₁BM spin-coated films at varied spin-coating parameters such as spin-rates and spin-step as well as blend properties including solution concentration, deposition techniques and donor–acceptor blend ratios. We related how deposition parameters affect the exciton quenching capabilities at donor–acceptor interface, film-surface homogeneity and light absorption in deposited films. From the optimized results obtained, deep photoluminescence quenching was observed for MEH-PPV doped with 75% PC₇₁BM in addition to reduced optical band gap energy (1.88 eV), a signature of improved charge transfer rate and photon-absorption. The optimized MEH-PPV: PC₇₁BM systems are possible candidates for photovoltaic applications especially in the production of thin organic photovoltaic solar cells.

Glass samples of CdO doped bario-fluoride borotellurite with nominal compositions of (45-x)B₂O₃ + 30TeO₂ + 15BaF₂ + 10Li₂O + xCdO and substitution ratios of x = 0.0 (Cd0.0), 0.5 (Cd0.5), 2.0 (Cd2.0), 4.0 (Cd4.0), and 7.0 (Cd7.0) mol% were synthesized using the well-known melt quenching process. The structure, physical, and optical characteristics of the prepared glasses have been investigated. The Phy-X/PSD software employed to evaluate the radiation attenuation competence of the prepared glasses. The XRD analysis confirmed that the Cd-0.0/Cd-7.0 samples were in amorphous nature. Density (ρ) varied from 3.8633 g/cm³ for Cd-0.0 sample to 4.2894 g/cm³ for Cd-7.0 sample. The molar volume (V_m) varied from 28.08 cm³/mol to 26.25 cm³/mol. The inclusion of CdO in the glasses network reduced the direct band gaps from 3.54 eV to 3.196 eV and the indirect band gaps from 3.23 eV to 2.85 eV, respectively. Urbach’s energy changed from 0.23 eV to 0.318 eV and refractive index (n) ranged between 2.333 and 2.439. Mass-absorption coefficient (MAC) values ranged between 30.696 − 0.032 cm²/g, 30.825–0.032 cm²/g, 31.210–0.032 cm²/g, 31.714–0.033 cm²/g and 32.450–0.033 cm²/g, for Cd0.0, Cd0.5, Cd2.0, Cd4.0, and Cd7.0 glass samples, respectively. Sample coded as Cd7.0 possessed the minimum half value layer (HVL) which ranged from 0.005 cm to 4.887 cm at photon energy 0.015 and 15 MeV, respectively. The effective atomic number (Z_eff) and effective ion density (N_eff) possessed the same trend of MAC parameter. Results confirmed that the present glasses are superior as γ-ray shields compared to other commercial materials.

Traditional lead-based solar cells are not easy to commercialize on a large scale due to their toxicity and instability to the environment and the human body. Tin-based perovskites have received widespread attention from scholars since they were discovered to have potential as absorber layers in perovskite solar cells. However, compared with lead-based perovskite solar cells (PSCs), tin-based perovskite solar cells as the absorber layer have lower power conversion efficiency. In addition, the most popular hole transport layer material is Spiro-OMeTAD, which is an expensive and poor stability organic material, which limits the development of PSC. To overcome the above issues, this work made a comprehensive optimization of the device structure by using SCAPS-1D software, and finally designed a high-performance all-inorganic CsSnI₃-based PSC. In addition, the electrical properties of the absorber layer are investigated by first-principles. Different from the traditional point-by-point optimization, this work adopts the two-factor dynamic optimization method, and the optimized power conversion efficiency is 30.58%, and the fill factor is 70.73%. This study demonstrates the potential of CsSnI₃ as an absorber layer of high-performance PSCs and provides guidance for future research on all-inorganic perovskite solar cells.

The mechanical stability, band gap enhancement, optical response and impact of pressure on thermoelectric figure of merit are considered vital parameters from thermoelectric device’s perspective based on SrZrO₃ (SZO). The knowledge of elastic constant expressed structural stability of SZO (cubic symmetry) even at elevated pressures. Cauchy’s pressure and Poisson’s ratios demonstrated brittle behavior of SZO till 10 GPa, and it transformed to ductile material for higher pressures. The topology of electronic band structure and its pressure effects are discussed with the help of density of states. Optical properties expressed significant shifting to higher energy values as a function of pressure. Seebeck coefficient and electrical conductivity showed an increasing trend with the application of external pressure, with no significant change in their graphical behavior from its ambient conditions. The lowest value of ZT is obtained at 40 GPa. The structural stability and sustained thermoelectric behavior at higher pressure declares SZO as ideal candidate for energy applications at extreme conditions.

A compact photonic method to generate frequency agile linearly frequency modulated (LFM) signals is proposed demonstrated by experiment and simulation. A Mach–Zehnder modulator driven by an LFM waveform train and an electrical controlled optical tunable delay line driven by a coding sequence is employed. According to time–frequency linear relationship of LFM signals, the initial frequency of the generated signals can be shifted by adjusting the introduced time delay. Experiments are carried out to verify the feasibility of the proposed generator. Frequency agile LFM signals under 2FSK and 4FSK modulation with symbol rate of 4 and 8 Msps are successfully obtained. 0.15 m range resolution and 4 Mbps communication data rate are achieved with a 1–1.5 GHz driving LFM signal. This scheme features compact structure and excellent tunability, which are promising to find applications in anti-jamming ISAC systems.

The fields of atomically thin two-dimensional transition metal dichalcogenides (2D TMDCs) have witnessed notable progress, resulting in a range of intriguing applications in nanoelectronics, photonics, sensing, energy storage, and opto-electronics. This article offers a comprehensive look at the latest progress in two-dimensional (2D) materials that go beyond graphene. Our main interest lies in TMDCs like MoS₂, WS₂, MoSe₂, and WSe₂. These materials are used in specific applications for advanced electronics and optoelectronics devices that depend on very thin atomic layers. Even though there have been challenges along the way in developing scalable and defect-free TMDCs on preferred substrates, scientists have managed to come up with innovative growth techniques that work well with both common and unconventional substrates. These developments have been driven by the increasing demand for precise and reliable TMDCs in real-world scenarios. TMDCs may play a critical role in the development in bio-medical applications, like biomedical imaging, medication administration, clinical diagnostics, and photodynamic therapy. A multilayer device architecture may facilitate the creation of a gate-defined quantum dot (QD) in transition metal dichalcogenides (TMDCs) for future quantum applications. Focus is on creating cutting-edge two-dimensional TMDCs with distinct features and new chemical characteristics. Furthermore, in addition to the realm of electronics, a considerable amount of research has focused on investigating the possibilities of these materials for energy and sensing applications, which are thoroughly analyzed.

We present a comprehensive performance analysis of injection-locked directly modulated laser (DML) for optical communication systems, focusing on both non-return-to-zero (NRZ) and 4-level pulse amplitude modulation (PAM4) signal transmission. We demonstrate real-time PAM4 40 Gbit/s transmission over 10 km of single-mode fiber enabled by optical injection locking without pre-emphasis or post-equalization, achieving a bit error rate (BER) below ({10^{-6}}), and doubling capacity compared to unlocked transmission with the same laser. Our study investigates the dependence of system performance on the injected power and frequency offset of the master laser. Results indicate that lower injection powers while maintaining a stable locking regime, yield better performance in terms of extinction ratio and BER. Optimized parameters lead to enhanced transmission performance, providing valuable insights into the design and optimization of injection-locked DML systems for optical communication applications employing direct modulation.

In this paper we investigate the behavior of localized solutions, specifically solitons, in a system of three coupled waveguides. The nonlinearity is modeled by a quasi-periodic modulation influencing the interaction between the waveguides. We analyze the evolution of the soliton profiles and their dynamics under varying modulation parameters, highlighting distinct behaviors such as attraction and repulsion among solitons. Our findings reveal that the system exhibits complex behaviors, depending on the interplay between the quasi-periodic modulation and the waveguide parameters. The study contributes to understanding the impact of quasi-periodic nonlinearity on soliton dynamics in coupled waveguide systems, laying the groundwork for potential applications in nonlinear optics and photonic devices.