Optical Absorption Efficiency Research Articles

High-Performance Flexible Broadband Photothermoelectric Photodetectors Based on Tellurium Films.

Mid- and far-infrared photodetectors that can operate at room temperature are essential for both civil and military applications. However, the widespread use of mid-to-far-infrared photonic technology faces challenges due to the need for low-temperature cooling of existing commercial semiconductors and the limited optical absorption efficiency of two-dimensional materials. We have utilized the photothermoelectric effect to fabricate a self-powered, broadband, and high-performance photodetector based on a one-dimensional tellurium nanorod array film. The device surpasses energy band gap limitations, functioning even at wavelengths up to approximately 10,600 nm. In particular, the detectivity of the device can reach 4.8 × 109 Jones at 4060 nm under room-temperature conditions, which is an order of magnitude higher than that of commercially available photodetectors. It demonstrates fast response and recovery times of 8.3 and 8.8 ms. Furthermore, the device demonstrates outstanding flexibility withstanding over 300 bending cycles and environmental stability. These results suggest a viable approach for designing and developing high-performance, room-temperature, wearable optoelectronic devices.

Design and full analysis of a metafiber-based photothermal bio-probe with perfect conversion efficiency

The metafiber, which involves fabricating metasurfaces at optical fiber tips, has shown potential as an integrated optical sensing or photothermal conversion platform. In this study, we present a metafiber-based photothermal bio-probe with a high optical absorption efficiency of 99.83%. Physical mechanisms underlying the efficiency are elucidated using coherent perfect absorption and multiple reflection theories. In our simulation, the probe exhibits ultra-fast heating/cooling rates, high temperature localization, steep temperature gradients, and robust response to environmental factors. In particular, only 1.0 mW of incident power is needed to generate the temperature gradient required for cell capture or drug delivery, while the corresponding temperature near the fiber tip is still safe for biological tissue. These advantages make our designed bio-probe as an ideal platform in various of applications, such as living cells capture, drug delivery, and local hyperthermia.

Dual functionality of the BiN monolayer: unraveling its photocatalytic and piezocatalytic water splitting properties.

To achieve scalable and economically viable green hydrogen (H2) production, the photocatalytic and piezocatalytic processes are promising methods. The key to successful overall water splitting (OWS) for H2 production in these processes is using suitable semiconductor catalysts with appropriate band edge potentials, efficient optical absorption, higher mechanical flexibility, and piezoelectric coefficients. Thus, we explore the bismuth nitride (BiN) monolayer using density functional theory simulations, revealing intriguing catalytic properties. The BiN monolayer is a semiconductor with an indirect electronic bandgap (Eg) of 2.08 eV and displays excellent visible light absorption (approximately 105 cm-1). Detailed analyses show that the band edges satisfy the redox potential for photocatalytic OWS via biaxial strain engineering and pH variation. Notably, the solar to hydrogen conversion efficiency (ηSTH) for the BiN monolayer can reach 17.18%, which exceeds the 10% efficiency limit of photocatalysts for economical green H2 production. The obtained in-plane piezoelectric coefficient of e11 = 16.18 Å C m-1 is superior to widely studied 2D materials. Moreover, the generated piezopotential under oscillatory strain stands at 28.34 V, which can initiate the water redox reaction via the piezocatalytic mechanism. This originates from the mechanical flexibility coupled with higher piezoelectric coefficients. The result highlights the BiN monolayer's potential application in photocatalytic, piezocatalytic, and photo-piezo-catalytic OWS.

A comprehensive investigation of the Sr3AsX3 (X = F/Cl/Br) inorganic cubic perovskites' strain-induced structural, electronic, optical, and mechanical properties with solar cell applications.

In comparison to the lead halide perovskites, nowadays, lead-free halide perovskites have demonstrated a number of benefits, including efficient optical absorption, increased stability, variable bandgap, excellent mobility of carriers, non-toxicity, abundant raw ingredients, and low manufacturing cost. The use of the Perdew-Burke-Ernzerhof (PBE) and Heyd-Scuseria-Ernzerhof (HSE) hybrid functional inside the quantum espresso software allowed for a thorough examination of these materials, potentially leading to improvements in the development of ecologically acceptable and economically sustainable perovskite-based products. This work has extensively examined the effects of compressive and tensile strain on the structural, optical, and electronic characteristics of the inorganic cubic perovskite Sr3AsX3 (X = F, Cl, Br) with varying X anion using first-principles density-functional theory (FP-DFT). At the Γ point, the unstrained Sr3AsF3, Sr3AsCl3, and Sr3AsBr3 compounds have a direct bandgap of 1.68/2.50 eV, 1.65/2.47 eV, and 1.522/2.30 eV, respectively, from the PBE/HSE methods. A drop in bandgap values occurs when the X-anion switches from F to Cl to Br. Furthermore, the bandgaps of the three proposed structures show a minor increase in response to tensile strain and a decreasing prevalence in response to compressive strain. The optical properties, which include dielectric functions, absorption coefficient, and electron loss function, are consistent with the band characteristics of these components, all of which point to a significant capability for absorption in the visible region. The dielectric constants of Sr3AsF3, Sr3AsCl3, and Sr3AsBr3 are discovered to have peaks that, with compressive strain, redshift (move towards lower photon energy) and, under tensile strain, blueshift (move towards upper photon energy). In comparison to the compounds Sr3AsF3 and Sr3AsCl3, the parameters indicate that the material Sr3AsBr3 is more optically advantageous. The SCAPS-1D simulator was used to methodically examine the photovoltaic (PV) performance of novel cell topologies that included SnS2 as an electron transport layer (ETL) and Sr3AsF3, Sr3AsCl3, and Sr3AsBr3 as absorbers and primarily 19.76, 19.89, and 20.89% PCE was achieved, respectively.

Development of nickel doped graphitic carbon nitride (GCN) photocatalyst for enhanced degradation of textile pollutant under visible light irradiation

An efficient rare earth metal (nickel) doped graphitic carbon nitride photocatalyst is developed by a facile synthesis approach. The synthesized nickel doped graphitic carbon nitride (x-NGCN) is employed for photocatalytic degradation of organic dye methylene blue (MB) simulated textile wastewater. It is observed that Ni doping of GCN enhances the optical absorption to such an extent that it efficiently degrades the MB dye under simple LED white light (5 W), mainly consisting of visible light range. Hence Ni doping resulted in sensitivity towards visible light range of spectrum due to narrowing of bandgap, thus increasing the photocatalytic performance. The prepared photocatalysts are characterized using various spectroscopy tools to investigate the crystallinity, morphology, functional groups, optical absorption, and charge separation efficiency.

The electronic and optical properties of InSe/ZnO van der Waals heterojunction:First principles study

The efficient, simple and low-cost photocatalysts has become a hot topic in the field of photocatalysis, ZnO has attracted the attention of researchers due to its high photocatalytic efficiency. Although, the broad band gap of around 3.4 eV in ZnO greatly limits its optical absorption efficiency. Based on this, two types of InSe/ZnO heterojunction models with different configurations are constructed, their electronic and optical properties are studied through first principles calculations. The results indicate that the II InSe/ZnO heterojunction has a band gap of 1.84 eV, which compensates for the shortcomings of ZnO monolayer broad band gap absorption of visible light and the difficulty of InSe monolayer in participating in water splitting oxidation reactions. The construction of heterojunctions using InSe and ZnO significantly improves the light absorption efficiency, especially in the visible spectral region, compared to ZnO monolayers, accelerating the generation and migration efficiency of photo generated electrons, thereby improving the catalytic efficiency of ZnO.

Designed Polymer Ligands for Perovskite Quantum Dots and Their Block Copolymer Nanocomposites

AbstractPerovskite quantum dots (QDs) have efficient optical absorption and emission in the visible range, and show a strong quantum confinement effect and high external quantum efficiency. They have been at the forefront of next‐generation photovoltaics and optoelectronics applications. However, two major challenges associated with perovskites and their nanomaterials are poor stability (such as against moisture and polar solvents), as well as the lack of efficient nanopatterning methods. In this work, a promising approach is provided to address both of those major challenges by molecular engineering and integration of QDs with block copolymers (BCP). The BCP thermoplastic elastomers not only substantially improve the stability of perovskite QDs by encapsulating them in a highly stable and soft matrix, but also enable molecular‐level control of the alignment and assembly of perovskite QDs in the microphase‐separated BCP matrix. It is demonstrated that designing and synthesis of compatible polymer ligands for perovskite QDs is key to enabling their selective and strong interaction with the BCP matrix. The structure and molecular weight of the BCP also play an important role in the interfacial structure and optical properties of the QDs‐BCP nanocomposites. Such soft and flexible optical nanocomposites have potential applications in flexible optoelectronics, optical storage, and displays.

Breaking symmetry of carbon nitride skeleton by embedding pyridine ring to promote photocatalytic performance

Breaking symmetry of polymeric carbon nitride (CN) skeleton by heteroatomic substitution can induce in-plane polar electric field, thus promoting the migration and separation of photoexcited charge carriers. Herein, a carbon-doped CN (pyCN) by embedding pyridine ring was prepared through a skeleton modification strategy. Owing to the n → π* electron transition and the formed in-plane polar electric field, the obtained pyCN displayed obvious extended optical absorption and photoinduced charge migration efficiency in comparison with pure CN. The optimized photocatalytic H2 evolution rate over pyCN reached 242.9 μmol·h−1, which is 6 times of that over pure CN with TEOA as a sacrifice. Additionally, the wavelength for H2 evolution over pyCN extends to 550 nm while that is 450 nm over pure CN, demonstrating an improved efficiency of sunlight utilization after skeleton modification. In addition, pyCN showed synergistic oxidation of bisphenol A (BPA) during hydrogen generation under visible light. The conversion efficiency of BPA reached 18.7 % in 24 h according to the external standard analysis. This work provides an efficient approach for enhancing optical absorption and inhibiting photoexcited charge recombination for higher photocatalytic performance and wilder applications.

Optical features and radiation absorption efficiency of borate glasses and the role of PbO/ Eu2O3 substitution

In the present research, the optical parameters and those related to the interactions of charged radiation and neutrons of 50B2O3 – 15Na2O – 15ZnO – (20-x)PbO-xEu2O3 (for x = 0, 2, and 3 mol%) glass system were investigated. The roles of Eu2O3 content on the evolution of the physical, optical, and shielding abilities of the glasses were presented. The glasses were prepared using the conventional melting-and-quenching method and coded as BNZPE1, BNZPE2, and BNZPE3 for Eu2O3x = 0, 2, and 3 mol%, respectively. To characterize the prepared glasses for radiation applications, two glasses of particulate radiation were considered: charged radiation and uncharged radiation.The densities of BNZPE1, BNZPE2, and BNZPE3 are 3.99 g/cm3, 4.02 g/cm3, and 4.27 g/cm3, respectively. The values of Eg are 3.04 eV, 3.28 eV, and 3.58 eV for BNZPE1, BNZPE2, and BNZPE3, respectively. Both Rm and αm followed a downward trend as Eu2O3 content rose. The static and optical dielectric constants decrease from 5.688 to 5.090 and 4.688 to 4.090, respectively, as the Eu2O3 content rises. The projected range of 15 MeV electrons, protons, alpha particles, and carbon ions was 20341 μm, 1010 μm, 96 μm, and 10.48 μm for BNZPE1, 20206 μm, 998.21 μm, 95 μm, and 10.42 μm for BNZPE2, and 19053 μm, 939.59 μm, 90 μm, and 9.82 μm for BNZPE3. The removal probabilities of FN in BNZPE1, BNZPE2, and BNZPE3 are 0.1086, 0.1089, and 0.1154 cm−1, respectively. The FN shielding abilities of the BNZPE-glasses are better than those of different categories of concrete and some known glass shields The glass with the highest Eu2O3 content has the highest charged particle FN, and TN interaction probabilities.

The photodetection characteristics of a Brilliant Blue-FCF implemented device for organic-based optoelectronic applications

The optical properties of sol-gel-based brilliant blue-FCF (BB-FCF) thin film are analyzed for photodetection applications. The effect of the presence of the BB-FCF interface on the microelectronic characteristics of the designated Cu/BB-FCF/n-Si device is elucidated by comparing to its reference Cu/n-Si device. The systematic investigation of photodetection properties of the integrated device is performed between the 20–100 mW/cm2 illumination intensities. First, the optical features of spin-coated BB-FCF thin film are investigated by UV–Vis measurements, and the absorbance of the film is elucidated by the efficient optical absorption in the wavelength of ∼350–700 nm with the calculated optical indirect band gap of 1.72 eV. Next, the frequency-dependent capacitive behavior, charge transport mechanism, and the electronic parameters of both the rectifying Cu/n-Si and the implemented Cu/BB-FCF/n-Si devices like the ideality factor, the barrier height, and series resistance are estimated using the Thermionic emission and Norde's function methods. Subsequently, the photodetection properties of the engineered device with a BB-FCF functional dye interface are studied under a solar simulator with different power intensities. The effect of the illumination intensity and applied reverse bias voltage on the figures of merit, including photoresponsivity, photodetectivity, response speed, and linear dynamic property, are analyzed under an illumination of 20–100 mW/cm2. The designated device with a BB-FCF interface has achieved significant and fast, stable on/off switching sensitivities, with 524 ms and 629 ms rising and falling times, respectively. Therefore, the prepared BB-FCF-based device has good and stable photoresponse performance, and the Cu/BB-FCF/n-Si architecture device may be a strong candidate for photonic and optoelectronic device applications, particularly in rapidly developing organic material-based device technology.

Pressure-dependent electronic, optical, and mechanical properties of antiperovskite X3NP (X = Ca, Mg): A first-principles study

Hydrostatic pressure provides an efficient way to tune and optimize the properties of solid materials without changing their composition. In this work, we investigate the electronic, optical, and mechanical properties of antiperovskite X3NP (X2+ = Ca, Mg) upon compression by first-principles calculations. Our results reveal that the system is anisotropic, and the lattice constant a of X3NP exhibits the fastest rate of decrease upon compression among the three directions, which is different from the typical Pnma phase of halide and chalcogenide perovskites. Meanwhile, Ca3NP has higher compressibility than Mg3NP due to its small bulk modulus. The electronic and optical properties of Mg3NP show small fluctuations upon compression, but those of Ca3NP are more sensitive to pressure due to its higher compressibility and lower unoccupied 3d orbital energy. For example, the band gap, lattice dielectric constant, and exciton binding energy of Ca3NP decrease rapidly as the pressure increases. In addition, the increase in pressure significantly improves the optical absorption and theoretical conversion efficiency of Ca3NP. Finally, the mechanical properties of X3NP are also increased upon compression due to the reduction in bond length, while inducing a brittle-to-ductile transition. Our research provides theoretical guidance and insights for future experimental tuning of the physical properties of antiperovskite semiconductors by pressure.

Electronic structures and photovoltaic properties of copper- or tin-doped cesium-based perovskite crystals

Electronic and crystal structures of CsPbIBr2 perovskite compounds doped with copper (Cu) or tin (Sn) were investigated. From the band calculations, an energy gap of CsPbIBr2 was reduced by the Cu or Sn doping, and optimized crystal structures of CsCuIBr2 were compared with the fabricated crystals. Energy gaps of Cu- or Sn-doped CsPbIBr2 were measured by optical absorption and external quantum efficiencies of the cells, and compared with the calculations. Addition of a small amount of Cu or Sn to the CsPbIBr2 increased the short-circuit current density of the fabricated solar cells, which agree with the expected results from the calculated band structures and partial density of states.

Synergistic Enhancement Mechanism of High Electron Density and Localized Surface Plasmons for Strong Light‐Matter Interactions

Abstract2D layered semiconductor materials hold the potential to address the crucial technical challenges of poor signal uniformity and low repeatability of traditional metal plasmonic nanostructures in sensing, which hinder quantitative detection and analysis in molecular detection. However, the ultra‐low light absorption efficiency and electronic state density intrinsically result in their inferior sensitivity compared with those of conventional metal plasmonic nanostructures. Therefore, the integration of the classical back‐gate modulation strategy and surface plasmon resonance into 2D heterostructures is proposed. This integration aims to control the interaction between the surface sensing material of the heterostructure and target molecules from the perspective of surface electronic state density and optical absorption efficiency. The sensitivity (≈10−12 m) of as‐designed MoS2/graphene/Ag heterojunction is comparable to that of advanced metal plasmonic nanostructures, and the corresponding enhancement factor (EF, 1.71 × 104) is much higher than that of most heterojunction‐based and metal‐semiconductor coupled devices. This study uncovers the internal mechanism of the surface plasmon effect and high electronic state density in enhancing light‐matter interactions, and provides an alternative avenue for high‐performance surface‐enhanced devices.

Two-dimensional MoSe2/PtSe2 van der Waals type-II heterostructure: Promising visible light photocatalyst for overall water splitting

The development of simple and efficient visible light photocatalytic catalysts for hydrogen production from water is an important development direction in the field of photocatalysis, and composite two-dimensional materials are found to be promising candidates. This paper constructs a novel two-dimensional MoSe2/PtSe2 type-II heterojunction and systematically studies its geometric structure, electronic structure, and optical properties by first-principles calculation. It is evident that the heterojunction has good thermodynamic, kinetic, and mechanical stability, as well as excellent hole carrier mobility, which is conducive to the separation of photogenerated electrons and holes. The optical properties show that MoSe2/PtSe2 heterojunction has the best optical absorption efficiency for visible light and has the ability to cross the water-cracking oxidation-reduction potential at pH = 4. More importantly, the MoSe2/PtSe2 heterojunction shows great hydrogen absorption reaction performance, indicating that it is a potential photocatalyst for overall water splitting of visible light, and has broad application prospects in the field of photocatalysis and optoelectronics.

Light trapping using a dimer of spherical nanoparticles based on titanium nitride for plasmonic solar cells

Light-trapping mechanisms with plasmonics are an excellent way to increase the efficiency of photovoltaics. Plasmonic dimer-shaped nanoparticles are effective in light absorption and scatterings, and there is hardly any research on dimer TiN nanoparticle-based PV. This paper demonstrated that titanium nitride could be a suitable substitute for other plasmonic materials in the visible and near-infrared spectrum. We designed a TiN-based spherical dimer plasmonic nanoparticle for photovoltaic applications. We conducted comparison analyses with the metals Ag, Au, and Al to ascertain the performance of TiN as a plasmonic material. Silicon had an average absorption power of ∼19%, and after incorporating TiN nanoparticles, the average absorbed power increased significantly to ∼75% over the whole spectral range. TiN dimer nanoparticle had the highest absorption cross-section, Q ab value ∼6.2 W/m2 greater than Ag, Au, and Al had a fraction of light scattered into the substrate value greater than Au, Al and comparable to Ag. TiN dimer exhibited better absorption enhancement, g for the whole spectral range than Ag, Au, and Al dimers for a radius of 15 nm with a peak value greater than 1. The maximum optical absorption efficiency of the plasmonic TiN nanostructures was ∼ 35.46%.

Extended-bandwidth solar nano-concentrator integrated with graphene-metamaterial for photovoltaic energy harvesting applications

Concentration photovoltaics are used to achieve solar energy focusing on small-area solar cells, thus obtaining a high efficiency at a reasonable cost. An array of gold plasmonic concentrator cells is proposed here, which can nano-focus the solar radiation down to 60 nm spot size. It works over the entire solar energy bandwidth up to 2400 nm wavelength, which is extended beyond the conventional solar cells known maximum operating wavelength of 1800 nm. The concentrator consists of a coaxial waveguide with a tapered section that can plasmonically nano-focus solar radiation, followed by a straight waveguide section to propagate focused light along a graphene metamaterial for optical absorption. The metamaterial is integrated within the 60 nm gap of the straight waveguide section. The metamaterial consists of 10 concentric graphene shell layers, which are cross-connected by 5 horizontal graphene annuli. The concentrator and metamaterial design maximizes the solar optical absorption efficiency within the graphene metamaterial. The graphene optical absorption is enhanced up to 27 times with an almost flat response covering most of the solar bandwidth. The plasmonic absorption within the gold surfaces of the structure is found to be reasonable. The enhanced optical absorption of the weak solar radiation received within the extended band (1800–2400 nm) can reach up to 50%. The concentrator device is polarization insensitive with a 120o field-of-view. The enhanced optical power absorption in graphene metamaterial could be used in photovoltaic energy harvesting applications.

Design of a direct Z-scheme GeC/arsenene van der Waals heterostructure as highly efficient photocatalysts for water splitting

The utilization of heterostructures as photocatalysts for water decomposition is a promising method to tackle contemporary environmental challenges. This research paper presents the design of a direct Z-scheme heterostructure utilizing a monolayer of GeC and a monolayer of arsenene, based on first-principle calculations. The photocatalytic efficiency of this GeC/arsenene van der Waals (vdW) heterostructure in a direct Z scheme has been investigated. The presence of a built-in electric field from the GeC monolayer to the arsenene monolayer has been established through an analysis of band alignment, work function, charge density, and Bader charge. The GeC/arsenene heterostructure exhibits excellent and robust optical absorption efficiency for the sunlight, alongside achieving the maximum solar-to-hydrogen (STH) energy conversion efficiency, amounting to 7.28%, under a biaxial strain of +4%. Furthermore, the Gibbs free energy changes in the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) of the GeC/arsenene heterostructure have been calculated. The outcomes indicate that the GeC/arsenene heterostructure is a feasible semiconductor for photocatalytic water splitting.

Modeling and Simulation of Fe-Doped GaN PCSS in High-Power Microwave

In this article, the characteristics of linear GaN photoconductive semiconductor switch (PCSS) in high-power microwaves are investigated by Silvaco TCAD (Technology Computer-Aided Design). By comparison of optical absorption efficiency among three types of PCSS structures, the optimized Fe-doped GaN PCSS is designed in a side-illuminated, vertical structure with a spot size of 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 8 mm. The photocurrent of side-illuminated GaN vertical PCSS (vPCSS) begins to saturate at 1.65 mJ with the increase of applied optical energy. The average saturated switch resistance and electron concentration of vPCSS under a bias voltage of 5–20 kV are almost 8.2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pmb\Omega $</tex-math> </inline-formula> and 3.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\text{14}}$</tex-math> </inline-formula> cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-\text{3}}$</tex-math> </inline-formula> , respectively. As the device is in a saturated photocurrent state, the peak photocurrent is a linear function of bias voltage. As the device is in an unsaturated photocurrent state, improving the light energy is more effective than the withstand voltage of the device to increase photocurrent. Due to the short carrier lifetime, the GaN vPCSS has the response capacity to a 50-ps pulsewidth laser. Based on side-illuminated GaN vPCSS at the bias field 200 kV/cm, a narrowband microwave with adjustable frequency (3.3–5 GHz) could be generated. The maximum output power reaches up to 1.3 kW. Effects of anti-reflective (AR) and reflective coatings on optical absorption are investigated. The photocurrent of vPCSS with both AR and reflective coatings increases by 77.2% as compared with normal vPCSS.

Highly Responsive Near-Infrared Si/Sb2Se3 Photodetector via Surface Engineering of Silicon.

The development of imaging technology and optical communication demands a photodetector with high responsiveness. As demonstrated by microfabrication and nanofabrication technology advancements, recent progress in plasmonic sensor technologies can address this need. However, these photodetectors have low optical absorption and ineffective charge carrier transport efficiency. Sb2Se3 is light-sensitive material with a high absorption coefficient, making it suitable for photodetector applications. We developed an efficient, scalable, low-cost near-infrared (NIR) photodetector based on a nanostructured Sb2Se3 film deposited on p-type micropyramidal Si (made via the wet chemical etching process), working on photoconductive phenomena. Our results proved that, at the optimized thickness of the Sb2Se3 layer, the proposed Si micropyramidal substrate enhanced the responsivity nearly two times, compared with that of the Sb2Se3 deposited on a flat Si reference sample and a glass/Sb2Se3 sample at 1064 nm (power density = 15 mW/cm2). More interestingly, the micropyramidal silicon-based device worked at 0 V bias, paving a path for self-bias devices. The highest specific detectivity of 2.25 × 1015 Jones was achieved at 15 mW/cm2 power density at a bias voltage of 0.5 V. It is demonstrated that the enhanced responsivity was closely linked with field enhancement due to the Kretschmann configuration of Si pyramids, which acts as hot spots for Si/Sb2Se3 junction. A high responsivity of 47.8 A W-1 proved it suitable for scalable and cost-effective plasmonic-based NIR photodetectors.

Nanocatalysts in photocatalytic water splitting for green hydrogen generation: Challenges and opportunities

Green hydrogen is a promising technology for sustainable energy production, with photocatalytic water splitting offering several advantages over wind/solar-powered water electrolysis. The focus of this review paper is on high-performance photocatalysts, which are key to improving the efficiency of photocatalytic hydrogen production. First, the general principles of photocatalytic hydrogen production and the factors affecting photocatalytic performance are summarized. Then, the conventional semiconductor photocatalysts including methods to improve their catalytic activities are comprehensively reviewed, which is followed by a detailed discussion of representative nano-photocatalysts. The performance of photocatalysts is affected by various factors, such as optical absorption, separation and transport efficiency of photocarriers, and redox capacity. The entire process of photocatalytic hydrogen production can be optimized through methods such as element doping, cocatalyst location, morphology adjustment, and heterojunction construction. Finally, photocatalysts of different dimensions, along with the challenges and future research directions, are summarized based on comparisons of numerous studies. This review provides a quick start guide for investigating the application of high-performance photocatalysts in green hydrogen production from photocatalytic hydrolysis, and offers insight into the latest advancements in photochemical conversion efficiency. It also provides a valuable reference for selecting nanomaterials and optimizing photocatalytic hydrogen production.