High-performance ZnTe/Bi2O2Se heterostructure photodetector for optical imaging applications

Contemporarily, the superior performance of low-dimensional heterostructure devices has attracted extensive attention of scientists. In order to offer a clearer understanding of low-dimensional materials and heterostructure devices, this paper introduces the basic concepts of low-dimensional materials and heterostructure fabrication and arranges the devices constructed by two-dimensional heterostructure materials. Primarily, the background information of state-of-art low-dimensional materials is demonstrated. Moreover, starting from the preparation of low dimensional materials, the mainstream methods of fabricating the two-dimensional materials are discussed. Then, the fabrication methods of two-dimensional material heterostructure and the general classification of two-dimensional material heterostructure devices are summarized. Last but not least, the full text is summarized and prospected. This paper aims to provide a more specific reference and guidance for the development of two-dimensional heterostructure devices in the future.

Complexation of Zn2+ with pyridyl Schiff base (ZnL2) was synthesized. The ZnL2 was examined and characterized using the elemental analysis, NMR, IR, UV-Vis, and mass spectra. ZnL2 was formed within 1:2 molar ratios of metal ion to ligand, respectively, which is proven by continuous variation method. The thin films of ZnL2 are grown on the quartz substrates for optical measurements using thermal evaporation method. The absorbance, transmittance, and reflectance were measured using a spectrophotometric technique, from which many optical parameters were determined. The indirect allowed transition is the most probable transition and the optical energy gap is found to be 2.41 eV. Additionally, the ZnL2 was tested as a photosensitizer material in the thin film form grown onto single crystal of p-Si wafer to form a hybrid organic-inorganic Au/ZnL2/p-Si/Al heterostructure device for the first time. Many electrical aspects were studied for such device including impedance spectroscopic, dielectric constant, electric modulus, and electrical conductivity at various frequencies and under different illumination intensities. The high photosensitivity of Au/ZnL2/p-Si/Al heterojunction for low and high power intensity of light confirmed that the ZnL2 material is a promising candidate photosensitizer for photovoltaic applications.

Far-red light mediates light energy capture and distribution in soybeans (Glycine max L.) under the shade

Sputtered transparent electrodes for optoelectronic devices: Induced damage and mitigation strategies

Lithium niobate is a universal material for optical applications (optical frequency conversion, optical and acoustooptical light modulation, lasing, photorefractive holography, etc.). This enormous versatility of optical properties is due to a pronounced dependence of its properties on composition, namely, on the crystal composition and the doping type. In spite of widespread potentials of LiNbO3, the optical frequency conversion still remains one of the most important. Although LiNbO3 is lower than other materials in rank, for example, potassium titanium oxide phosphate (KTP) with larger values of the nonlinear optical coefficients, nevertheless, the possibility to obtain a noncritical (90◦) phase matching and a rather broad angular width of the phase synchronism makes LiNbO3 one of the most attractive materials for nonlinear optics. The use of LiNbO3 for optical frequency conversion on a regular pattern of 180◦ ferroelectric domains in the quasiphase-matching (QPM) mode of operation is within the bounds of possibility. Detailed descriptions of the properties of LiNbO3 and its optical applications may be found in numerous reviews and monographs [1, 2, 3]. In nonlinear optics the performance of LiNbO3 is limited by three optically induced effects. The first of them, optical (or photorefractive) damage, is a reversible photoinduced change of the refractive indices that appears at relatively low light intensities, for example in LiNbO3:Fe even at power densities as low as a tenth of a mW/cm2, e.g., [1]). In undoped (congruent) LiNbO3 a saturated photoinduced change δn of the refractive indices is as high as 2 · 10−5–10−4. The consequences of the optical damage are, for example, a distortion of the wave front of the transmitted light, and a loss of lasing when using the material as a laser medium. The second effect limiting the use of many crystals in optics is the dark (or gray) trace effect, which is a light-induced coloration occurring in

The world’s energy demand is continuously increasing. Non-renewable energy sources, such as petroleum and coal, are extremely limited. On the other hand, conversion efficiency of renewable energy sources into useful forms is insufficient. In our study, we pursued methods to make more efficient solar cells – in particular, photo-electrochemical (PEC) solar cells. We selected the Molybdenum diselenide (MoSe2) based PEC solar cell because of its high resistance to corrosion. First, we explored the relationship between light intensity and efficiency of PEC solar cells. We expected that corrosion of the PEC solar cell would increase with increase in intensity of incident light. Thus, we hypothesized that the efficiency of the solar cell would decrease with increased intensity of incident light. Further, we investigated the relationship between solar cell efficiency and electrolyte volume. We hypothesized that efficiency of PEC solar cell would increase as the electrolyte volume increased. We analyzed several parameters— such as light intensity, fill factor, efficiency, etc.—to draw conclusions. First, we found that percentage efficiency of PEC solar cell was proportional to (light intensity)-0.9. Further analysis showed that PEC solar cell performance was positively influenced by increasing the electrolyte volume. Data revealed that this increase in solar cell performance was more consequential at low intensities of light (around 10 mW/cm2). Our study could contribute to improving the quality of PEC solar cells and might help in the development of carbon-free hydrogen economy.

Influence of twin boundaries on the photocurrent decay of nanobranch and dense-forest structured SnO2 UV photodetectors

Recent advances on visible light photoinitiators of polymerization based on Indane-1,3-dione and related derivatives

This study used reduced graphene oxide (rGO) applied to a platinum (Pt) counter electrode to improve light conversion efficiency. The study also used an Al-doped Zinc Oxide (AZO) nanosheet/TiO2 photoanode for the dye-sensitized solar cell (DSSC). Photovoltaic characteristics, electrochemical impedance spectroscopy (EIS), field-emission scanning electron microscopy (FE-SEM) and Raman spectroscopy were used to analyze DSSC. The different light intensities and photovoltaic characteristics were analyzed to determine optimal light intensity conditions. The unmodified Pt counter electrode was compared with the rGO/Pt counter electrode, photovoltaic conversion efficiency ( ${\eta }$ ) increased from 3.60% to 4.04% due to the rGO modification as it possesses a higher specific surface area. Its low cost also makes it suitable for mass production. In addition, an AZO nanosheet/TiO2 photoanode was fabricated to form a double-layer structure in which photovoltaic conversion efficiency was 4.47 %. Finally, a DSSC with an AZO/TiO2 photoanode and rGO/Pt counter electrode was fabricated and had an photovoltaic conversion efficiency of 5.05 %. This study also analyzed the photovoltaic parameters of DSSC under different light intensities, which shows the optimal photovoltaic conversion efficiency of 5.54% under 30mW/cm2.

The acclimation of plants to light has been studied extensively, yet little is known about the effect of dynamic fluctuations in light on plant phenotype and acclimatory responses. We mimicked natural fluctuations in light over a diurnal period to examine the effect on the photosynthetic processes and growth of Arabidopsis (Arabidopsis thaliana). High and low light intensities, delivered via a realistic dynamic fluctuating or square wave pattern, were used to grow and assess plants. Plants subjected to square wave light had thicker leaves and greater photosynthetic capacity compared with fluctuating light-grown plants. This, together with elevated levels of proteins associated with electron transport, indicates greater investment in leaf structural components and photosynthetic processes. In contrast, plants grown under fluctuating light had thinner leaves, lower leaf light absorption, but maintained similar photosynthetic rates per unit leaf area to square wave-grown plants. Despite high light use efficiency, plants grown under fluctuating light had a slow growth rate early in development, likely due to the fact that plants grown under fluctuating conditions were not able to fully utilize the light energy absorbed for carbon fixation. Diurnal leaf-level measurements revealed a negative feedback control of photosynthesis, resulting in a decrease in total diurnal carbon assimilated of at least 20%. These findings highlight that growing plants under square wave growth conditions ultimately fails to predict plant performance under realistic light regimes and stress the importance of considering fluctuations in incident light in future experiments that aim to infer plant productivity under natural conditions in the field.

Nonlinear frequency conversion in thin-film lithium niobate (TFLN) is a promising method for visible light generation. In particular, efficient green light generation remains challenging due to the lack of direct gain media, making nonlinear frequency conversion a viable alternative. Here, we demonstrate an efficient approach that combines modal phase-matching (MPM) and quasi-phase-matching (QPM) in a single TFLN waveguide with a single poling period, enabling green light generation under continuous-wave (CW) pumping. Second harmonic generation (SHG) occurs between fundamental transverse electric (TE) modes, while third harmonic generation (THG) is phase-matched with the higher-order TE20 mode, verified by mode profile measurements. Our device achieves normalized conversion efficiencies of 795%W-1cm-2 (SHG) and 2,775%W-2cm-4 (THG), with on-chip SHG power reaching the mW level and THG power in the μW range. This compact and scalable design offers an efficient green light source for applications in quantum optics, bio-imaging, and advanced display technology.

<p>The projected extension of growing season length under climate change will increase the carbon uptake potential of forest ecosystems at high latitudes. However, the dynamics of carbon uptake in high latitudes, namely ecosystem scale photosynthesis have not been well represented in existing carbon models yet. This impedes the unbiased assessment of current and predicted carbon dynamics at regional and continental scales. For instance, a substantial overestimation of simulated (by applying a state-of-the-art terrestrial photosynthesis model (P-model)) compared to gross primary productivity (GPP) derived from eddy-covariance (EC) was found in early spring for many sites and years. Here we show a substantial reduction of this GPP overestimation by adding a stress function accounting for the effects of low temperature and high light intensity. We found the strong depression of light use efficiency (LUE) in the GPP overestimation sites, which is related to the high photosynthetic photon flux density (PPFD) and low daily minimum temperatures (T<sub>min</sub>) during the early spring and preceding weeks or months. This mismatch between modelled and EC-derived GPP can be attributed to the adjustment of leaf properties and photosynthesis, e.g., synthesizing photoprotective pigments while reducing photosynthesis pigments in evergreen trees in the cold periods to protect the photosynthesis apparatus from damage from excessive light (photoprotection). This is supported by the observed high red chromatic coordinates (RCC) and delayed increase of green chromatic coordinates (GCC) from digital repeat photography. Finally, through embedding an empirical stress function considering the direct and lagged impact from T<sub>min</sub> into the model, we improved the GPP estimation and reduced the model-observation mismatch in GPP in early spring. Our results demonstrate one way to improve the GPP estimation in high latitude ecosystem by taking the physiological processes (e.g. photoprotection) into account. This enables a more accurate estimation of the continental carbon dynamics under climate change.</p>

We systematically study the influence of interface configuration and strain on the electronic and transport properties of lateral MoS2/graphene heterostructures by first-principles calculations and quantum transport simulations. We first identify the favorable heterostructure configurations with C-S and/or C-Mo bonds at the interfaces. Strain can be applied to graphene or MoS2 and would not change the relative stabilities of different heterostructures. Band alignment calculations show that all the lateral heterostructures have n-type Schottky contacts. The current-voltage characteristics of the lateral MoS2/graphene heterostructure diodes exhibit good rectification performance. Too strong and too weak interface interactions do not benefit electronic transport. The MoS2/graphene heterostructures with moderate C-S bonds at the interface have larger currents through the junctions than those with C-Mo bonds at the interface. The maximal rectification ratio of the lateral diode with strain applied to MoS2 can reach up to 105. With strain applied to graphene, the currents through the heterostructures can increase by 1-2 orders of magnitude due to the reduced Schottky barrier heights at the interface, but the rectification ratio is reduced with a maximal value of 104. Our calculations can serve as a theoretical guide to design rectifier and diode devices based on two-dimensional lateral heterostructures.

Integrated quantum well bipolar devices for tunable detection and optical logic applications

Flower-like Bi2S3–In2S3 heterojunction for efficient solar light induced photoreduction of Cr(VI)