Light Conversion Efficiency Research Articles

Over 1500 PPI quantum dot color conversion array by lift‐off

AbstractThis study explores the application of lift‐off process for the patterning of quantum dot (QD) pixels using CdSe/ZnS core‐shell colloidal QDs. The evaluation of the influence of different solvent and binder systems on the effectiveness of the pixelation is detaily discussed. By optimizing the solvent and binder combination, the fabrication of multi‐color QD patterns with pixel sizes ranging from 5 to 200 μm were demonstrated, achieving blue light conversion efficiencies exceeding 18% and 25% for red and green pixels. It is also improved pixel uniformity, stability, and resolution, lying the foundation for the development of ultra‐high‐resolution, QD Micro‐LED display. However, challenges remain in maximizing the utilization of blue light and packaging of QD layers. Future research will aim to develop high‐quality QD inks suitable for photoresist lift‐off and optimize the QD Micro‐LED system to further enhance the performance and stability of QD‐based displays.

Quantum Dot Luminescence Microspheres Enable Ultra-Efficient and Bright Micro-LEDs.

Quantum dot (QD)-converted micrometer-scale light-emitting diodes (micro-LEDs) are regarded as an effective solution for achieving high-performance full-color micro-LED displays because of their narrow-band emission, simplified mass transfer, facile drive circuits, and low cost. However, these micro-LEDs suffer from significant blue light leakage and unsatisfactory electroluminescence properties due to the poor light conversion efficiency and stability of the QDs. Herein, the construction of green and red QD luminescence microspheres with the simultaneously high conversion efficiency of blue light and strong photoluminescence stability are proposed. These luminescence microspheres exhibit high external photoluminescence quantum yields exceeding 46% under 450nm excitation, along with excellent reliability against blue light, heat, and water-oxygen degradation, owing to the waveguide and spatial confinement effects of the microspheres. The microsphere-based green and red micro-LEDs achieve world-record external quantum efficiencies of 40.8% and 22.1%, respectively, and high brightness values of 1.7×108 and 7.6×107cdm-2, respectively. Finally, 0.6inch red, green, and blue monochrome micro-LED displays are demonstrated by integrating microsphere-converted micro-LED arrays with thin-film transistor backplanes, which show a pixel resolution as high as 1700 PPI and brightness exceeding 10000cdm-2.

Exogenous Application of Lanthanum Chloride to Rice at Booting Stage Can Increase Chlorophyll Content, Modulate Chlorophyll Fluorescence and Promote Grain Yield Under Deficit Irrigation

To sustain agricultural productivity and safeguard global food security, and confront the escalating challenges posed by climate change and water scarcity, it is essential to enhance the growth and productivity of rice under water stress. This study investigated the effects of lanthanum chloride on the chlorophyll fluorescence characteristics and grain yield of rice under different irrigation modes. The rice cultivar H You 518 was selected and sprayed 20, 100, or 200 mg·L−1 lanthanum chloride at the booting and heading stages under deficit irrigation (where no rewatering was applied after the initiation of stress, allowing the water layer to evaporate naturally under high temperatures) or conventional irrigation (with daily rewatering to maintain a consistent water level). The results showed that the application of low concentrations lanthanum chloride promoted the chlorophyll content, whereas high concentrations decreased the chlorophyll content, under deficit irrigation, the effect of lanthanum chloride on the green fluorescence parameters of rice leaves at the booting stage was greater than that at the heading stage, and the booting stage was more sensitive to water deficit. The application of 100 mg·L−1 lanthanum chloride reduced the initial fluorescence (F0) and the non-photochemical quenching coefficient (qN); promoted the activity of leaf photosynthetic system II (PSII); and maximized the photochemical quantum yield (Fv/Fm), photochemical quenching coefficient (qP), and PSII relative electron transfer efficiency (ETR). Under deficit irrigation, this treatment significantly enhanced grain yield by increasing the thousand-grain weight, spikelet filling rate, and number of grains per panicle. These results suggest that spraying 100 mg·L−1 lanthanum chloride at the booting stage under deficit irrigation can effectively increase the chlorophyll content, thereby increasing the light energy conversion efficiency of the PS II reaction center, ultimately resulting in increased spikelet filling rate and grain yields.

Ultra-Narrowband Green-Emitting Transparent Composite Ceramics for Laser-Driven Display.

Laser-driven projection displays face a critical challenge in developing laser-excitable and high-performance narrowband green emitters. Herein, new Al2O3-LaMgAl11O19: Mn2+ (Al2O3-LMA: Mn2+) transparent composite ceramics are reported via high-temperature vacuum sintering, which produces a high-color-purity (95.4%) green emission with full width at half maximum of 24nm and superior thermal and moisture and laser irradiation stability. These are attributed to low electron-phonon couple, weak crystal-field effect, an individual lattice location of Mn2+ activators in high structural rigid host, and the incorporation of a high-thermal-conductivity Al2O3 secondary phase. As a result, the composite ceramics are demonstrated as an attractive color converter with a high external quantum efficiency (38%) and absorption coefficient (53%), which ensures a luminous flux of 2012lm @40.0W, a luminous efficacy of 67.7lmW-1, and a green light conversion efficiency of 20.3% upon blue laser irradiation. This enables to construct a brand-new laser-driven prototype display with a record color gamut beyond Rec.2020 standard (100.8%), outperforming commercial YAG: Ce3+ and β-SiAlON: Eu2+. This exploration in ultra-narrowband green luminescent materials is poised to accelerate the development of "ideal displays" for laser-driven projection display technology.

Quinoidal Semiconductor Nanoparticles for NIR-II Photoacoustic Imaging and Photoimmunotherapy of Cancer.

Photoagents with ultra-high near-infrared II (NIR-II) light energy conversion efficiency hold great promise in tumor phototherapy due to their ability to penetrate deeper tissues and minimize damage to surrounding healthy cells. However, the development of NIR-II photoagents remain challenging. In this study, an all-fused-ring quinoidal acceptor-donor-acceptor (A-D-A) molecule, SKCN, with a BTP core is synthesized, and nanoparticles named FA-SNPs are prepared. The unique quinoidal structure enhances π-electron delocalization and bond length uniformity, significantly reducing the bandgap of SKCN, resulting in strong NIR-II absorption, a high molar extinction coefficient, and a photothermal conversion efficiency of 75.14%. Enhanced molecular rigidity also facilitates efficient energy transfer to oxygen, boosting reactive oxygen species generation. By incorporating the immunomodulator R848, FA-SRNPs nanoparticles are further developed, effectively modulating the tumor immune microenvironment by reducing Tregs and M-MDSCs infiltration, promoting dendritic cell maturation, M1 macrophage polarization, and activating CD8+ T cells and NK cells. Comprehensive studies using orthotopic ovarian cancer models demonstrated strong tumor targeting, photoacoustic imaging capabilities, and significant tumor suppression and metastasis inhibition, and also showing excellent therapeutic efficacy in an orthotopic breast cancer model. This study provides strong evidence for the potential application of quinoidal A-D-A molecules in cancer photoimmunotherapy.

Efficient photo-assisted reduction of Cr(VI) via activated carbon mediated Z-scheme FeS2/α-FeOOH/C heterojunction: Focusing on molecular oxygen fate and synergetic reduction mechanism

Herein, pyrite (FeS2), goethite (α-FeOOH) and activated carbon (C) were combined to construct FeS2/α-FeOOH/C composites with C mediated Z-scheme heterojunction for efficient photo-assisted Cr(VI) reduction. Characterization tests indicated the strong interaction via Fe-O-C and C-S-C, the increased amount of crystal defects and surface oxygenic functional groups, and the decreased agglomeration degree during combination strengthened electron transport and visible light conversion efficiency, resulting in synergistic effect for enhanced Cr(VI) removal. Additionally, C mediated Z-scheme heterojunction with lower resistance facilitated the transfer and separation efficiency of photo-generated carriers, further accelerating Cr(VI) reduction. Consequently, almost 100 % of Cr(VI) was reduced via FeS2/α-FeOOH/C in 60 min, 4 times that of pristine FeS2. Quenching, EPR and control experiments confirmed photocatalysis made more contribution than single reductive reagents (FeS2) in Cr(VI) reduction. The specific contribution rate of reductive species like e−, Fe2+, S22− and •O2− in this complicated system was firstly detailedly demonstrated and •O2− played a predominant role under oxic condition. Meanwhile, oxidative species like H2O2, 1O2 and •OH ascribed to DO activation or photo-generated h+ preferred to reacted with Fe2+ and S22− with higher reducibility and-only delayed Cr(VI) reduction rate. Hence, the final total Cr(VI) removal efficiency and generated Cr(III) kept stable in oxic solution.

Ultrahighly-efficient and stable luminescent solar concentrators enabled by FRET-based carbon nanodots

Luminescent solar concentrators (LSCs) as an optical device to concentrate light from large areas illuminated by sunlight into small-area photovoltaic cells, can greatly reduce the cost of solar energy generation, thus showing promise in building-integrated photovoltaics. Here, we report the synthesis of a novel type of composite nanoparticle via the simple sol-gel method. Starting from hydroxyl-rich carbon nanodots (CDs), Rhodamine B (RhB) molecules were embedded into a silica matrix shell, forming a composite core-shell system, where the CDs represent the core and RhB embedded in SiO2 are the shell of the final CDs/RhB@SiO2 structure. These nanoparticles were successfully employed in high-performance LSC fabrication. The Förster resonant energy transfer (FRET) between the CDs and the dye was successfully exploited to improve the light absorption efficiency and power conversion efficiency (ηPCE) of LSC devices. The solid-state photoluminescence quantum yield of the as-synthesized composite nanoparticles can reach ∼ 57 % due to the effective suppression of the aggregation-induced quenching. These fluorescent composite nanoparticles were used for fabricating LSC devices with an ultrahigh ηPCE of ∼ 3.8 % for 5 × 5 cm2 devices, thanks to the high loading of luminophores and effective FRET.

Effects of exogenous melatonin on drought stress in celery (Apium graveolens L.): unraveling the modulation of chlorophyll and glucose metabolism pathways

Drought, a prevalent abiotic stressor, significantly impacts plant yield and quality. Melatonin (MT), a potent and economical growth regulator, plays a pivotal role in augmenting crop resilience against stress. This study investigated the efficacy of exogenous MT on drought-stressed celery seedlings by comprehensively analyzing phenotypic, physiological, and molecular attributes. The results revealed that exogenous MT mitigated celery seedling damage under drought stress, lowered malondialdehyde (MDA) concentrations, elevated oxidase activities, osmolyte levels, chlorophyll content, and augmented light energy conversion efficiency. Transcriptomic analysis demonstrated that MT could regulate chlorophyll synthesis genes (AgPORA1 and AgDVR2), contributing to heightened photosynthetic potential and increased drought tolerance in celery. Moreover, MT was found to modulate glycolytic pathways, upregulate pyruvate synthesis genes (AgPEP1 and AgPK3), and downregulate degradation genes (AgPDC2 and AgPDHA2), thereby promoting pyruvate accumulation and enhancing peroxidase activity and drought tolerance. The RNA-seq and qRT-PCR analyses demonstrated similar results, showing the same general expression trends. The study elucidates the physiological and molecular mechanisms underlying MT’s stress-alleviating effects in celery seedlings, offering insights into MT-based strategies in plant cultivation and breeding for arid environments.

Enhancement of non-oleaginous green microalgae Ulothrix for bio-fixing CO2 and producing biofuels by ARTP mutagenesis

Oleaginous green microalgae are often mentioned in algae-based biodiesel industry, but most of them belong to specific genus (Chlorella, Scenedesmus, Botryococcus and Desmodesmus). Thus, the microalgal germplasm resources for biodiesel production are limited. Mutagenesis is regarded as an important technology for expanding germplasm resources. The main purpose of this study is to screen microalgae strains with high carbon dioxide tolerance and high lipid content from mutants derived from indigenous non-oleaginous green microalgae species—Ulothrix SDJZ-17. Two mutants with high CO2 tolerance and high lipid content genetic stability were obtained from the mutants by high-throughput screening, named Ulothrix SDJZ-17-A20 and Ulothrix SDJZ-17-A23. In order to evaluate the potential of CO2 fixation and biofuel production, A20 and A23 were cultured under air and 15% CO2 (v/v) conditions, and their wild-type strains (WT) were used as controls. Under the condition of high CO2 concentration, the growth performance and lipid production capacity of mutant strains A20 and A23 were not only significantly better than those of wild strains, but also better than those of their own cultured under air conditions. Among them, A23 obtained the highest LCE (light conversion efficiency) (14.79%), Fv/Fm (maximal photochemical efficiency of photosystem II) (71.04%) and biomass productivity (81.26 mg L−1 d−1), while A20 obtained the highest lipid content (22.45%). Both mutants can be used as candidate strains for CO2 fixation and biofuel production. By ARTP (atmospheric and room temperature plasma) mutagenesis with high-throughput screening, the mutants with higher CO2 tolerance, photosynthetic efficiency and lipid productivity can be obtained, even if they are derived from non-oleaginous microalgae, which is of great significance for enriching the energy microalgae germplasm bank, alleviating the global warming and energy crisis.

Event-based high-resolution neutron image formation analysis using intensified CMOS cameras

We present a versatile optical setup for high-resolution neutron imaging with an adaptable field of view and magnification that can resolve individual neutron absorption events with an image intensifier and a CMOS camera. Its imaging performance is characterized by evaluating the resolution limits of the individual optical components and resulting design aspects are discussed. Neutron radiography measurements of a Siemens star pattern were performed in event mode acquisition comparing two common high-resolution neutron scintillators, crystalline Gadolinium Gallium Garnet (GGG) and powdered Gadolinium Oxysulfide (GOS). An analysis of the light signature caused by neutron absorption events is performed and some resulting issues for both GGG and GOS regarding optical system design are addressed. Both scintillators reach similar resolution (4–5 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\upmu }$$\\end{document}m) in event mode acquisition despite different light emission characteristics. The findings suggest that, in the case of GOS, the resolution is limited by the size of the light clusters which in turn originate from the photon scattering at the boundaries of the powder particles comprising it, while with GGG the lower light conversion efficiency makes it challenging to collect enough photons to trigger sufficient signal amplification in the image intensifier. Overall, the proposed event-based evaluation of scintillators allows for quantifying and optimizing various design parameters, which is much more complex than adopting conventional methods based on integrated images.

Enhancing the efficiency of wavelength-shift fiber-based detectors for optical wireless communications

A wavelength-shift fiber-based optical detector promises to revolutionize the deployment of optical wireless communication (OWC) due to its inherent advantages over traditional receivers. These advantages include a flexible structure, a wide field of view (FOV), and a large active area. Despite progress in previous studies, there remains a gap in optimizing the re-utilization of unabsorbed light within wavelength-shift fiber (WSF) and maximizing the efficiency of light focusing onto photodetectors. To address these challenges, this study explores three novel, to the best of our knowledge, approaches to enhance the light conversion and detection efficiency of WSF-based optical detectors. First, a reflective mirror is employed behind the WSF array to increase the light absorption and re-emission probability. Second, a reflective mirror is placed at one end of the WSF array to direct the light toward the opposite end. Third, a tightly bundled WSF array configuration focuses the emitted light onto the photodetector’s active area. Experimental results demonstrate that each approach significantly improves the peak-to-peak voltage. This work presents an optical detector design featuring a large active area of 0.4cm×20cm, based on a blue-to-green color-converting WSF and achieving a high 3-dB bandwidth of up to 48 MHz. This design enables real-time data transmission at rates of 275 Mbps using non-return-to-zero on-off keying (NRZ-OOK) modulation over a distance of 1 m. Additionally, the transmission link operates at over 250 Mbps, with bit error rates (BERs) below the forward error correction (FEC) limit, under a wide FOV of 60°. This work opens exciting possibilities for revolutionizing photodetection schemes in non-line-of-sight free-space optical communications.

Enhanced efficiency, electron lifetime, and eco-friendliness of dye-sensitized solar cells using nanofibrous TiO2/ZnO composite photoanodes and natural anthocyanin sensitizer

Semiconductor is the main part of the photoanode in dye-sensitized solar cells (DSSCs). In this study, an evaluation was conducted on two different morphological shapes of TiO2/ZnO semiconductors, namely nanoparticles (NPs) and nanofibers (NFs), to enhance the efficiency of DSSCs. The nanofibrous semiconductors were fabricated using the electrospinning technique. Furthermore, a natural sensitizer, anthocyanin dye, was used to promote the environmental friendliness of the fabricated cells. These cells were then compared to those that used a synthetic dye known as N719 to determine their efficiencies. The UV–vis results confirmed the extraction of anthocyanin from black plum fruits (Syzygium cumini). The structural characteristics of the composites were examined using XRD, FE-SEM, and BET experiments. The XRD results revealed that the anatase phase of TiO2 was dominant in the crystal structure of the semiconductors, while the crystallite sizes of the composites were 25.04 nm and 12.24 nm in NPs and NFs forms, respectively. The FE-SEM analysis revealed the formation of quasi-spherical NPs with an average diameter of 48.26 ± 17.75 nm and NFs with an average diameter of 153.99 ± 26.18 nm. The BET results showed that the surface characteristics of the nanocomposite were enhanced by changing the shape from NPs to NFs. Photovoltaic studies showed that utilizing NFs semiconductors in the photoanodes of DSSCs resulted in increased conversion efficiency of light to electricity. The results of the sun simulator studies confirmed that the use of natural dye led to a decrease in the effectiveness of the DSSCs. This phenomenon can be attributed to the weaker binding of the natural dye to the photoanodes. Furthermore, the EIS investigations illustrated that the electron lifetime in the natural dye is more than twice that of N719, leading to a reduced rate of electron recombination in the Syzygium cumini extract. The TiO2/ZnO NFs photoanodes exhibited superior performance compared to their nanoparticle counterparts in DSSCs. Their high surface area promoted superior dye adsorption and light absorption. Moreover, the interconnected nanofiber network facilitated efficient electron transport, minimizing recombination losses. Increasing the binding strength of the chosen natural dye to the photoanode will also make the cells more environmentally friendly and improve their ability to produce electricity.

Anion-Driven Bandgap Tuning of AgIn(SxSe1-x)2 Quantum Dots.

Accurate tuning of the electronic and photophysical properties of quantum dots is required to maximize the light conversion efficiencies in semiconductor-assisted processes. Herein, we report a facile synthetic procedure for AgIn(SxSe1-x)2 quantum dots with S content (x) ranging from 1 to 0. This simple approach allowed us to tune the bandgap (2.6-1.9 eV) and extend the absorption of AgIn(SxSe1-x)2 quantum dots to lower photon energies (near-IR) while maintaining a small QD size (∼5 nm). Ultraviolet spectroscopy studies revealed that the change in the bandgap is modulated by the electronic shifts in both the valence band and the conduction band positions. The negative overall charge of the as-synthesized quantum dots enabled us to make films of quantum dots on mesoscopic TiO2. Excited state studies of the AgIn(SxSe1-x)2 quantum dot films demonstrated a fast charge injection to TiO2, and the electron transfer rate constant was found to be 1.5-3.5 × 1011 s-1. The results of this work present AgIn(SxSe1-x)2 quantum dots synthesized by the one-step method as a potential candidate for designing light-harvesting assemblies.

Illumination optimization strategies to enhance hydrogen productivity and light conversion efficiency for photo-fermentation by Rhodobacter sphaeroides KKU-PS1 using a concentrated multi-substrate feedstock

With the use of biotechnology, hydrogen can be produced from wastewater rich in short-chain fatty acids. A previous study revealed the ability of Rhodobacter sphaeroides KKU-PS1 to produce biohydrogen from substrates mimicking succinate fermentation effluent. However, the process still requires optimization. Before illumination optimization, due to high concentration of the effluent, various effluent dilution factors ranging from 10 to 100 were compared, and the optimal dilution factor was determined to be 50. Light-emitting diode (LED) setups consisting of bands and tubes were compared, and various illuminated surface-to-volume ratios (S/V) were obtained. LED tubes were subsequently used for light intensity optimization in the range of 5–23 klux, revealing optimum light intensity at 15 klux, yielding 2202 mL H2/L and 13.8 mL H2/L/h as the cumulative hydrogen and maximum output rate, respectively. The lighting protocol at 15 klux and with a 6h–6h light-dark cycle improved the total light conversion efficiency by up to 3.1%. The study successfully optimized the process, with results rivalling those of a previous study using malate.

Synthesis and characterization of new perylenediimide derivatives: Promising low-cost electron transport materials for perovskite solar cells

In organic-inorganic perovskite solar cells (PSCs), the electron transport layer (ETL) plays a crucial role providing efficient electron extraction and transport required for achieving high device performance. Compared to traditional fullerene-based electron-transport materials (ETMs), non-fullerene small molecules have attracted much attention due to their tunable optoelectronic properties, lower cost, and much higher stability. In this work, we synthesized and characterized four perylenediimide (PDI) derivatives and investigated their optoelectronic properties in the context of application as ETMs for PSCs. To establish the compatibility of PDI films with perovskite absorber material, the surface properties of Cs0.12FA0.88PbI3/PDI bilayer stacks were studied using contact angle and infrared scattering scanning near-field microscopy methods. A study of the photochemical stability of these bilayer stacks showed that coating the perovskite film with a layer of PDI improves its tolerance with respect to light. Utilizing these molecules as ETMs in the inverted p-i-n PSCs delivered light power conversion efficiencies ranging from 11.1 % to 15.4 %, thus indicating the considerable effect of the PDI derivative molecular structure on the photovoltaic properties. Further development of this research direction may lead to the rational design of advanced PDI-based electron transport materials for efficient and stable PSCs.

Study of hybrid nanoscatterer for enhancing light efficiency of quantum dot-converted light-emitting diodes

Optical scatterer additives play a critical role in enhancing the light conversion efficiency and uniformity of quantum dot-converted light-emitting diodes (Qc-LEDs). This study investigates the impact of optical characteristics and morphology of nanoscatterer on the light conversion and extraction efficiency of Qc-LEDs. Various metal oxides and boron nitride nanoparticles and nanoplates with different diffraction index were selected to carry out the study. Finite-Difference Time-Domain (FDTD) simulation was employed to evaluate the scattering effect of various nanosphere and nanoplate scatterers on the optical performance of the Qc-LEDs. The simulation results revealed that the hybrid nanoscatterer integrates the forward-scattering from the nanosphere and backward-scattering of blue light from the nanoplate. Spectral analysis was conducted to examine the optical performance of Qc-LEDs with varying combinations and concentrations of nanoscatterers. TiO2 nanoparticles and Al2O3 nanoplates were found to be the best combination for maximal light conversion and extraction efficiency within Qc-LEDs. The results indicate an optimal light efficiency is obtained with the optimal ratio of 1:2:2 for quantum dots, TiO2 nanoparticles, and Al2O3 nanoplates. These findings reveal the relationship between optical properties, morphology, and light conversion efficiency in Qc-LEDs, highlighting the advantages of the hybrid nanoscatterers for improving optical performance of Qc-LEDs.

Synergistic interplay of photobioreactor mixing and static mixer configuration on Rhodoseupdomonas palustris’s growth and biohydrogen production

Inducing light/dark (L/D) cycles through mixing or recirculating the media in a photobioreactor improves light utilization for biohydrogen production during photoferentation. However, the mutual shading effect is a key challenge for photofermentation using purple non-sulphur bacteria (PNSB). In this study, mixing was explored as a mitigating methodology through the investigation of three different static mixer configurations: concentric, spiral, and half-moon, across four laminar flowrates: 1.2 L/min, 0.71 L/min, 0.31 L/min and 0.15 L/min. At 0.15 L/min, the half-moon and spiral static mixers significantly improved specific and cumulative hydrogen production by 11.2-fold and 114 %, respectively. Also, recirculating the fluid via a peristaltic pump resulted in a significant shearing effect, impacting cell viability. Inducing L/D cycles via a static mixer was thus beneficial for hydrogen production over an increased flow rate. Additionally, biomass productivity increased by up to 70 %, reaching a cell dry weight of 7.0 g/L with the spiral static mixer configuration at 0.15 L/min flow rate. Interestingly, this study found that the static mixers only significantly increased specific hydrogen production and light conversion efficiency at the lowest flow rate of 0.15 L/min, beyond which they showed no significant improvement in biohydrogen production. This indicates that high L/D cycling frequencies are unnecessary to alleviate the mutual shading effect for R. palustris, which is advantageous for upscaling. These findings emphasise the potential of static mixers as an alternative to increase light conversion efficiency and industrial hydrogen production.

Compact 2-μm Hundred Hertz optical parametric oscillator Based on KTP crystal

A 100 Hz compact 2 μm optical parametric oscillator (OPO) based on a type II non-critically phase-matched KTiOPO4 crystal (KTP) was reported. The monolithic KTP crystal was pumped with a passively Q-switched 1064 nm Nd:YAG laser. At a repetition rate of 100 Hz and a single pulse energy of 5.8 mJ of pump light, a 2128-nm laser output was achieved with a maximum of 1.17 mJ of parametric light at the degenerate point, with a parametric light pulse width of approximately 10.5 ns, corresponding to a pump to parametric light conversion efficiency of 20.1 %.

Revealing the secrets of high performance lead-free CsSnCl3 based perovskite solar cell: A dive into DFT and SCAPS-1D numerical insights

In this study, a CsSnCl3/CBTS based hetero structure solar cell is proposed by incorporating effective ETLs like CBTS and HTLs built on C60. At first, electrical and optical properties of CsSnCl3 is determined with the help of DFT study. Those parameters are incorporated in SCAPS-1D to design the proposed solar cell. Numerical analysis demonstrates that heterostructures consisting of ITO/C60/CsSnCl3/CBTS/Au display remarkable photoconversion efficacy. In addition, the impact of CsSnCl3 thickness, series resistance, light conversion efficiency, also working temperature is investigated additionally to optimize the cell performance. Furthermore, the composed impacts of thickness of absorber and ETL, defect density, electron affinity (eV), absorption thickness, and doping are also explored. The SCAPS-1D simulation results, which show an ideal open-circuit voltage of 1.18 V, a short-circuit current density of 22.22 mA/cm2, a fill factor of 87 %, and an overall efficiency of 20.5 %, are in good agreement with both simulated and experimental data published in the literature. This thorough simulation analysis provides insightful information and identifies a viable path for future CsSnCl3-based solar cell development.

Ultrafast dynamics and mechanism of structure formation in titanium nitride upon femtosecond laser irradiation for plasmonic enhanced photothermal effect

Femtosecond laser has great potential in controlling the surface structure of titanium nitride (TiN) to promote plasmonic photothermal effect. Studying the mechanism of femtosecond laser irradiation on the surface and inside of the TiN benefits the photothermal microdevices. Ultrafast dynamics of electrons and lattices of TiN films with different thicknesses were first studied through pump-probe technique, which found that the electron density is easier to reach the maximum on the surface than the electrons in deep-layers. High-frequency ripple was formed by tiny nucleation resulted from weak eruption of surface material on the thin TiN film, and low-frequency ripple was emerged through large nucleation of material clusters simultaneously on the thick TiN film. The blue shift and intensity changes of Raman peak on 200 nm TiN film indicate the heterogeneous structure changed from TiN to TiN0.26 after laser processing, and the vacancy occupies causes the lattice vibration weakened. The 200 nm TiN film after processing shows enhanced local surface plasma resonance absorption effect, which induced the reflectivity is reduced by 30 %, and the light and thermal conversion efficiency increased by 80 %. These results proved the promising utilization of TiN in biological and medical applications, energy collection and thermal auxiliary magnetic records.