PL Properties Research Articles

Reinforcement of various characteristics of biocompatible PVA/PMMA/N-GO polymer nanocomposite by functionalization of GO

ABSTRACT This article explores the reinforcement of various characteristics of a biocompatible PVA/PMMA polymer blend through the incorporation of functionalized graphene oxide (N-GO). PVA/PMMA/N-GO nanocomposites were synthesized using a melt blending technique with varying N-GO wt.%. Characterization revealed significant improvements: reduced refractive index and optical bandgap, increased extinction coefficient, Urbach energy, and optical dielectric constants. XRD analysis showed enhanced crystallinity and reduced micro-strain, indicating suitability for high-performance applications. FTIR analysis detected minor shifts in functional groups (O-H, C-H, C-O, and C-C), while PL properties were modulated. In addition, the antibacterial activities of the prepared polymer nanocomposites have been investigated against Escherichia coli (gram-negative bacteria) and Bacillus subtilis (gram-positive bacterial). These results demonstrate the potential of PVA/PMMA/N-GO composites for diverse technological applications.

Synthesis and application of lead iodine-based perovskite nanomaterials

In this study, we employed a modified ligand-assisted recrystallization precipitation (LARP) method to synthesize perovskite nanomaterials with emission peaks ranging from 515 nm to 683 nm. The synthesis of these nanomaterials with different emission peaks was achieved by simply controlling the type and amount of cesium oleate. These CsPbI3 nanomaterials possess different morphologies, and all of them show excellent PL properties. Furthermore, by simply mixing the nanomaterials with sodium citrate, a large quantity of powders of various colors was obtained, which can be used for the fabrication of multicolor patterns.

Tailored Carbon Dots in Solar Energy Conversion Schemes

Addressing the dual challenge of meeting the world's escalating energy needs while simultaneously decreasing carbon dioxide emissions has emerged as a pivotal issue in the new millennium. The Statistical Review of World Energy's latest report by British Petroleum Company plc reveals that global power consumption was around 18.9 terawatts (TW) in 2021, with projections estimating a surge to 30 TW by 2050. In stark contrast, solar radiation delivers a 120,000 TW to the Earth's surface, a quantity that exceeds the projected energy consumption of 2050 by 4,000 times. Efficiently harnessing and storing this immense solar energy is increasingly seen as a viable route towards a sustainable energy network. A promising solution lies in carbon-based systems. Carbon dots (CDs), an emerging class of nanomaterials, show great potential in this field. These can be synthesized through scalable methods using various carbon and nitrogen precursors, including waste, making them both cost-effective and recyclable. CDs offer a range of photophysical properties, such as variable photoluminescence and the generation of spin-active states. Furthermore, CDs are biocompatible, non-toxic, and environmentally friendly. Unlike traditional binary semiconductors, their photocatalytic attributes can be finely adjusted using a variety of organic chemistry functionalization techniques. While CDs have primarily been optimized for PL properties, their application in metal-free photocatalysis remains largely untapped. Major obstacles are the large structural diversity and complex multicomponent arrangement of CDs, along with the high variability of their photoactive centers, presenting a unique challenge. The ongoing controversy over the exact CDs structure, further compounded by a limited understanding of how this structure influences their photophysical properties, significantly hinders advancements in CDs design. This challenge significantly hampers progress in the development of more effective CDs for solar-driven water-splitting, underscoring the urgent need for increased collaboration between experimentalists and theoreticians now more than ever. In this contribution, we delve into the current understanding of photocatalytically active CD-based systems. The focus is set on model systems that feature no co-catalysts. We explore the role of CDs, shed light on the structure-activity relationship and detail photon- and charge-management in the excited state. Additionally, we share our insights on the potential opportunities that emerge from a deeper comprehension of CDs.

Structural, morphological and photoluminescence studies of Ca7Mg2P6O24:RE3+(RE3+= Tb3+, Dy3+) nanophosphor for solid state illumination

The Ca7Mg2P6O24:RE3+ (RE3+= Tb3+, Dy3+) nanophosphor material was synthesized by traditional wet chemical method. The XRD are used to determine phase and crystallinity of the synthesized sample; further FTIR, SEM, TEM, and PL properties were studied. The XRD pattern of prepared sample match well with standard JCPDS card no 00–020–0348, and it exhibits the rhombohedral structure along with space group R3c (161). The phosphate (PO4)3-group absorption band was observed at 990–1100 cm-1 in FTIR. Surface morphology (TEM analysis) reveals particle sizes in the range of 55–110 nm. The luminescence emission spectra of Ca7Mg2P6O24 phosphor activated by Tb3+ were studied at three different excitations: 352 nm, 370 nm, and 379 nm. The spectra show two emission peaks at 470 nm (blue) and 545 nm (green). These are due to the 5D4 → 7F6 and 5D4 → 7F5 transitions of Tb3+ ions. The highest intensity peak is located at 545 nm. The Ca7Mg2P6O24:Tb3+ phosphor's CIE chromaticity coordinates are (0.040, 0.316) at 491 nm and (0.265, 0.724) at 543 nm. These are in the blue and green areas on the edges of the CIE diagram, respectively. The photoluminescence emission spectra of Dy3+-doped Ca7Mg2P6O24 phosphor show two significant emission peaks located at 482 nm and 574 nm. These are caused by the 4F9/2 → 5H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+ ions, which produce blue and yellow light, respectively, with an excitation wavelength of 350 nm. The sharp peak position at 482 nm produces the strongest emission. The effect of concentration quenching in between the Dy3+-Dy3+ions and Tb3+-Tb3+ ions is due to dipole-dipole interaction. The CIE color coordinate is found to be (0.082, 0.156) at 482 nm and (0.471, 0.527) at 574 nm which lies in blue and yellow border of CIE diagram. The lifespan of Tb3+, Dy3+activated Ca7Mg2P6O24 nanophosphor of highest concentration is found to be 1.917 ms and 0.9985 ms respectively. On investigation, the synthesized Tb3+, Dy3+activated Ca7Mg2P6O24 nanophosphor can be potential for solid lightning devices & other display application.

Synthesis and investigation of the optical characteristics of RE3+ activated Ca2Li2Si2O7 (Rare earth = Eu, Tb) phosphor for W-LED application

Novel Eu3+ and Tb3+ ions-doped Ca2Li2Si2O7 luminescent materials were prepared by a low-temperature solid-state reaction technique for LED application. The electronic transitions of 5D0 → 7F2 (Eu3+) and 5D4 → 7F5 (Tb3+) have caused the luminescent material to exhibit strong luminosity in 613 nm (red) and 545 nm (green), respectively. Fourier transform infrared (FT-IR) spectra were applied for the identification of functional groups, and powder X-ray diffraction (XRD) was used for structural analysis. Morphological data was gathered using scanning electron microscopy (SEM). Its color was also determined by calculating the CIE coordinates. The excitation, PL properties, and luminescence decay time of the emission transitions of Eu3+ (5D0 → 7F2) and Tb3+ (5D4 → 7F5) were measured in order to analyze luminosity spectra.

Self–Trapped Exciton versus Band–Edge Electron Transitions: Insights of the Factors Affecting the Optical Properties of Lead–Free Sn–Halide Perovskites

AbstractLead–free Sn–halide perovskites (Sn–HPs) are attractive photomaterials due to their lower toxicity, and some of them with higher stability against moisture and water, compared to their Pb‐based analogous. Interestingly, Sn‐HPs can exhibit two types of optical characteristics: the first scenario is known as band‐edge electron transitions [or band‐to‐band (b‐b) emission], where accumulated electrons in the conduction band recombine with holes in the valence band, providing a close separation between the absorption edge/photoluminescence (PL) peak (small Stokes shift). The second scenario is denominated as self‐trapped exciton (STE), where intraband gap energy states are formed to trap photocarriers generated in the perovskite, producing a broadband PL and a large Stokes shift. These optical features have been suitable for developing prominent devices, but there is no consolidated explanation about the key factors influencing the emergence of b–b emission or STE in Sn‐HPs, mainly the presence of these PL mechanisms in a particular perovskite system. This review highlights how the chemical composition, structural defects, and synthetic procedures are pivotal to producing Sn‐HPs with specific b–b or STE features. This will allow the preparation of Sn‐HPs with better quality/stability, and facile modulation of their PL properties, expanding their future applicability in LCD technologies.

Modulation of High-Intensity Optical Properties in CdS/CdSe/CdS Spherical Quantum Wells by CdSe Layer Thickness.

Spherical quantum wells (SQWs) have proven to be excellent materials for suppressing Auger recombination due to their expanded confinement volume. However, research on the factors and mechanisms of their high-intensity optical properties, such as multiexciton properties and third-order optical nonlinearities, remains incomplete, limiting further optimization of these properties. Here, a series of CdS/CdSe (xML)/CdS SQWs with varying CdSe layer thicknesses were prepared. The modulation effects of CdSe shell variations on the PL properties, defect distribution, biexciton binding energy, and third-order optical nonlinearities of the SQWs were investigated, and their impact on the material's multiexciton properties was further analyzed. Results showed that the typical CdS/CdSe(3ML)/CdS sample exhibited a large volume-normalized two-photon absorption cross-section (18.17 × 102 GM/nm3) and favorable biexciton characteristics. Optical amplification was observed at 12.4 μJ/cm2 and 1.02 mJ/cm2 under one-photon (400 nm) and two-photon (800 nm) excitation, respectively. Furthermore, different amplified spontaneous emission spectra were observed for the first time under one/two-photon excitation. This phenomenon was attributed to thermal effects overcoming the biexciton binding energy. This study provides valuable insights for further optimizing multiexciton gain characteristics in SQWs and developing optical gain applications.

High Efficiency Non‐Doped Organic Light Emitting Diodes Based on Pure Organic Room Temperature Phosphorescence by High‐Lying Singlet Exciton Fission

AbstractHeavy‐metal‐free pure organic room temperature phosphorescence (ORTP) holds great potential in the field of organic optoelectronic devices owing to low economic cost, simple preparation techniques, and high exciton utilization. However, it is still filled with challenges in realizing high efficiency organic light‐emitting diodes (OLEDs) and exploring the internal physical mechanism based on these ORTP molecules. Here, a high‐performance OLED induced by an unexpected interfacial spin‐mixing process between the ORTP molecule and interlayers is demonstrated, and the high efficiency electroluminescence (EL) mechanism is studied through magneto–electroluminescence (MEL) and magneto–photoluminescence (MPL) measurements. The steady‐state and transient PL properties imply that the interfacial effect is related to a high‐lying singlet fission (HLSF) process in the ORTP molecule itself. Further, the HLSF process and the corresponding energy level position are confirmed by the incident wavelength‐ and temperature‐dependent PL spectra and the magnetic‐field‐dependent transient PL. Finally, by optimizing the interfacial material adjacent to the emissive layer to utilize this interfacial spin mixing effect, a high‐efficiency non‐doped ORTP‐OLED with external quantum efficiency of 16% and CIE coordinates of (0.27, 0.49) is developed. The proposed mechanism during the EL process will give insight to produce more efficient OLEDs based on ORTP materials in the future.

Regulating ligand length to improve the PL QY and stability of CsPbCl0.9Br2.1 nanocrystals for LEDs and photoelectric applications

Perovskite luminescent materials have been extensively investigated due to their comprehensive applications for full-color display, lighting, and communication. However, the development of blue-emissive perovskites has seriously lagged behind that of green and red counterparts, primarily because of their low photoluminescence quantum yield (PL QY) and poor stability. Here, we prepared blue-emissive CsPbCl0.9Br2.1 perovskite nanocrystals (PeNCs) and enhanced their QY from 61.3 % to 90.4 % by regulating the chain lengths of ligands. Post-treated PeNCs also exhibit good stability, their PL intensity is maintained at about 90 % after storage at ambient conditions for 10 days. The exciton dynamics results obtained from time-resolved fluorescence spectra and transient absorption spectra show that dodecyldimethylammonium bromide (DDAB), featuring double 12-hydrocarbon chains, is more capable of passivating surface defects and inhibiting non-radiative composites than the other double 8- or double 16-carbon chain ligands, which greatly improved the probability and rate of radiative recombination. Subsequently, the mechanism of ligand chain length regulation on the PL properties and stability of PeNCs was analyzed in terms of ligand-NC surface interaction, ligand polarity, hydrophobicity, and spatial effects. Furthermore, the device based on DDAB-CsPbCl0.9Br2.1 demonstrated stable EL and long operation lifetime, indicating its significant potential as an efficient blue emitter for backlighting in display technologies.

Photoluminescence Tuning of Stable CaYGaO4: Bi/Eu via Compositional Modulation and Crystallographic Site Engineering for nUV wLEDs.

The olivine-based gallate CaYGaO4 (CYG) with unique cationic ordering, rich lattice sites, and self-photoluminescence (PL) is suitable for application as a host of phosphor. However, research in this area is still in its early stages, especially in high-quality full-spectrum white lighting. Herein, novel CYG: Bi3+/Eu3+ with a controllable PL property is designed based on energy transfer and superposition of emissions from blue self-PL, blue PL of Bi3+, and red-PL of Eu3+. Intriguingly, PL intensity and quantum efficiency could be enhanced via codoping Li+/Zn2+ separately/simultaneously because of their two intentional functions as both charge balancer and flux. Unlike self- and Eu3+ PL, Bi3+ PL is quite sensitive to the lattice environment owing to its exposed 6s2 electronic configuration and is tuned via codoping Sr2+ to regulate the nephelauxetic effect and crystal field splitting concurrently around Bi3+. Meanwhile, for further regulating the PL of Bi3+ and obtaining "warm" white light, La3+ is codoped into the phosphor via crystallographic site engineering to control the substitution trends of Bi3+ at distinct lattice sites. Finally, as a proof-of-concept, a full-spectrum phosphor-converted white-light-emitting diode device under nUV pumping with remarkable color rendering index (Ra), high luminous efficiency, and chemical/thermal stability is achieved by utilizing the individual CYG:Bi/Eu/Li/Zn/Sr/La phosphor via a remote "capping" packaging method.

Realizing efficient near-infrared emission in Cu-In-S/ZnS quantum dots: Aqueous synthesis, optical properties and applications

Ternary I-III-VI quantum dots (QDs) are promising substitutions to Pb and Cd chalcogenide QDs in various applications such as LED, biodetection and sensing. It is urgent to explore near-infrared (NIR) emitting QDs with the advantages of low-cost synthesis and nontoxicity. Herein, water-soluble NIR Cu-In-S/ZnS (CIS/ZnS) QDs were obtained utilizing thioglycolic acid (TGA) and polyethyleneimine (PEI) as the stabilizing molecules in a commercial pressure cooker. Moreover, we detailedly investigated the influence factors on the PL property of CIS QDs and CIS/ZnS QDs including species of sulfur source, reaction time, pH, the dosage of TGA, PEI, Na2S, number of ZnS coating layers and the molar ratio of Cu/In. These QDs with adjusting Cu/In ratios show the emission maximum in the range of 710–750 nm. The maximum PL quantum yield (PLQY) of 20 % was acquired for CIS/ZnS QDs with a Cu/In ratio was 0.33/1 and three ZnS layer coating. Finally, we fabricated a NIR pc-LED lamp by using blue LED chips and CIS/ZnS QDs. The device shows a broadband NIR emission centered at 770 nm, which can be applied in night-vision system.

Rigid Phase Formation and Sb3+ Doping of Tin (IV) Halide Hybrids toward Photoluminescence Enhancement and Tuning for Anti‐Counterfeiting and Information Encryption

AbstractMulti‐excitonic emitting materials in luminescent metal halides are emerging candidates for anti‐counterfeiting and information encryption applications. Herein, ATPP2SnCl6 (ATPP=acetonyltriphenylphosphonium) phase was designed and synthesized by rationally choosing emissive organic reagent of ATPPCl and non‐toxic stable metal ions of Sn4+, and Sb3+ was further doped into ATPP2SnCl6 to tune the photoluminescence with external self‐trapped excitons emission. The derived non‐toxic ATPP2SnCl6 shows multi‐excitonic luminescent centers verified by optical study and differential charge‐density from density functional theory calculations. Incorporation of Sb3+ dopants and the increasing concentrations induce the efficient energy transfer therein, thus enhancing photoluminescence quantum yield from 5.1 % to 73.8 %. The multi‐excitonic emission inspires the creation of information encryption and decryption by leveraging the photoluminescence from ATPPCl to ATPP2SnCl6 host and ATPP2SnCl6 : Sb3+. This study facilitates the anti‐counterfeiting application by employing solution‐processable luminescent metal halides materials with excitation‐dependent PL properties.

Rigid Phase Formation and Sb3+ Doping of Tin (IV) Halide Hybrids toward Photoluminescence Enhancement and Tuning for Anti-Counterfeiting and Information Encryption.

Multi-excitonic emitting materials in luminescent metal halides are emerging candidates for anti-counterfeiting and information encryption applications. Herein, ATPP2SnCl6 (ATPP=acetonyltriphenylphosphonium) phase was designed and synthesized by rationally choosing emissive organic reagent of ATPPCl and non-toxic stable metal ions of Sn4+, and Sb3+ was further doped into ATPP2SnCl6 to tune the photoluminescence with external self-trapped excitons emission. The derived non-toxic ATPP2SnCl6 shows multi-excitonic luminescent centers verified by optical study and differential charge-density from density functional theory calculations. Incorporation of Sb3+ dopants and the increasing concentrations induce the efficient energy transfer therein, thus enhancing photoluminescence quantum yield from 5.1 % to 73.8 %. The multi-excitonic emission inspires the creation of information encryption and decryption by leveraging the photoluminescence from ATPPCl to ATPP2SnCl6 host and ATPP2SnCl6 : Sb3+. This study facilitates the anti-counterfeiting application by employing solution-processable luminescent metal halides materials with excitation-dependent PL properties.

Effect of different BaO contents on the photoluminescence properties of the Eu2+-doped high thermal stability Sr3−xBaxMgSi2O8 phosphors

In this study, 0.015 Eu[Formula: see text]-doped Sr[Formula: see text]BaxMgSi2O8 ([Formula: see text], 0.3, 0.6, 0.9) were used as compositions to find the effect of BaO content on their photoluminescence excitation (PLE) and photoluminescence emission (PL) properties. They were sintered at 1400°C in a reduction atmosphere of 95% N[Formula: see text]% H2 to form blue phosphors. X-ray diffraction pattern and SEM observation were used to analyze their crystal properties, and a fluorescence spectrophotometer was used to analyze their PLE and PL properties. After conducting a thorough analysis, our research primarily encompasses four significant research themes. First, SEM observations revealed that synthesized Eu[Formula: see text]-doped Sr[Formula: see text]BaxMgSi2O8 phosphors exhibit the formation of whisker-like structures. Therefore, the whisker-like structures in all the Eu[Formula: see text]-doped Sr[Formula: see text]BaxMgSi2O8 phosphors were analyzed using the HRTEM and its equipped EDS to find how BaO content influenced both the quantity and fineness of these whiskers. Second, we examined the impact of BaO content on the PLE and PL emission intensities of the Eu[Formula: see text]-doped Sr[Formula: see text]BaxMgSi2O8 phosphors across a temperature range from room temperature to 210°C. This investigation aimed to uncover the effects of BaO content and temperature on the thermal stability of the Eu[Formula: see text]-doped Sr[Formula: see text]BaxMgSi2O8 phosphors. Lastly, our fourth important investigation involved reorganizing the PLE spectra of the Eu[Formula: see text]-doped Sr[Formula: see text]BaxMgSi2O8 phosphors with the energy band as the x-axis. The Gaussian fitting function was applied to analyze the excitation spectra and discern the influence of BaO content on the value of the Stokes shift.

Mn derived growth of CsPbBr3 nanoplatelets for stable and bright orange emission

Abstract Mn-doped perovskites have been extensively studied in optics, magnetism, and electronics due to their orange emission. However, successful Mn doping required a high Mn/Pb feed ratio. In this paper, Mn-doped CsPbBr3 nanoplatelets (NPLs) with bright orange emission were prepared by a two-step slow thermal injection synthesis. The slow injection of precursors effectively slow-down the crystal growth kinetic process and controls the growth of undoped CsPbBr3 NPLs. This process also significantly improves Mn doping efficiency. Mn doping induced the generation of numerous precursor clusters during the growth of CsPbBr3 NPLs, and the formation of these clusters was crucial for enhancing the doping efficiency. The maximum amount of Mn precursor in CsPb0.83Mn0.17Br3 was 50% of Pb precursors. The photoluminescence quantum yields (PLQYs) of CsPb0.94Mn0.06Br3 NPLs reached up to 80.6%, which was 3.1 times of that of CsPbBr3 NPLs. The PL properties of Mn-doped CsPbBr3 NPLs were significantly enhanced compared with pure CsPbBr3 NPLs. The growth process and luminescence mechanism of Mn-doped CsPbBr3 NPLs were discussed. High PLQYs and efficient Mn doping supplied an ideal approach for the preparation of various CsPbX3 (X = Cl, Br, and I) NCs for commercial applications.

Efficient Near‐Infrared Fluorescence in Deuterated Host–Guest System for Near‐Infrared Organic Light‐Emitting Diodes

AbstractNear‐infrared organic light‐emitting diodes (NIR‐OLEDs) possess substantial potential for future valuable applications, such as a light source for sensing applications. However, the low photoluminescence quantum yield (PLQY) of NIR‐emitting molecules represents a significant impediment to these applications. In this study, the impact of the deuteration of both of host (mCP‐d20: 1,3‐Dicarbazole‐benzene‐d20) and guest (BBT‐TPA‐d28: 4,8‐bis[4‐(N,N‐diphenylamino)phenyl]benzo[1,2‐c:4,5‐c']bis[1,2,5]thiadiazole‐d28) on NIR PL properties in the host–guest codeposited film is reported. The 1 wt%‐BBT‐TPA‐d28:mCP‐d20 codeposited film exhibited PLQY of 15 ± 2% with an emission peak wavelength at ≈900 nm, which is about three times higher than that of the film composed of undeuterated molecules. Importantly, the deuteration of only the host or guest does not yield the PLQY up to 15%, underlining the importance of the deuteration of both host and guest molecules in suppressing nonradiative decay processes. The NIR‐OLED with the deuterated codeposited film as an emissive layer demonstrates a maximum external electroluminescence quantum efficiency of 2.3 ± 0.2%.

Dysprosium hydroxide nanoparticle-embedded photoluminescent composite films

Dy(NO3)3 was dissolved in water–ethanol complex solvent, and the obtained solution was used to fabricate composite films wherein Dy compound particles were embedded in a transparent urethane resin. All the resulting composite films exhibited photoluminescence properties attributed to the Dy-based compounds. When the composite films were prepared by varying the water/ethanol ratio of the raw material solution, the PL intensity was stronger when the water content of the composites was higher. Further ultraviolet irradiation of the resulting films caused the disappearance of the Dy–OH bonds and decrease in the PL intensity of the films. The increase in the PL intensity with increasing water content was attributed to the presence of Dy–OH bonds in the films. In addition, we investigated the presence and PL properties of Dy–OH bonds in Dy-based particle composite films.

Structural and optical properties of ZnGa2−x(YbXCrGe)xO4 (X = Ho and Er) up-conversion photoluminescence materials

ZnGa2−x(YbXCrGe)xO4 (X = Ho3+, Er3+) compounds are prepared using the solid-state-reaction method. Alteration in the lattice parameters and strain signifies the substitutional doping of elements at the octahedrally coordinated Ga3+ ions. Down-shifting PL properties are observed at the excitation wavelength of 275 nm. NIR wavelength (980 nm) induced up-conversion PL is observed in the Yb and Ho and/or Er doped samples. The prominent green-colored emission is observed in Yb3+ and Ho3+ doped sample and intense red-colored emission is achieved in the Yb3+ and Er3+ doped sample. The existence of up-conversion photoluminescence is mechanistically discussed by considering the energy transfer processes among the Zn2+, Ga3+, Yb3+, Ge3+, Cr3+, Er3+, and Ho3+ ions.

Single‐Layer Carbon Nitride as an Efficient Metal‐Free Organic Electron‐Transport Material with a Tunable Work Function

AbstractSingle‐layer carbon nitride (SLCN) is introduced as a metal‐free organic electron transport material (ETL) for organic solar cells, delivering a performance comparable to that of the benchmark nanocrystalline ZnO. SLCN is produced in the form of stable aqueous inks and can serve as an efficient electron transport layer for three different types of active layers, showing high stability to photodegradation. A lower conductivity of SLCN films as compared to ZnO is counter‐balanced by their higher transparency and lower light scattering losses. The SLCN ETL provides a unique opportunity to tune the work function from ca. −4.1 to −4.6 eV by varying the annealing temperature due to partial thermal oxidation of the SLCN film. The PL band position follows the oxidation‐induced changes of the work function allowing PL properties of SLCN to be used to predict the PV efficiency. The 2D structure of SLCN coupled with unique structural and compositional variability, and tunability of the work function show a high promise for emerging organic PV devices.

Photocatalytic activity of hollow mesoporous SiO2-BiOI/CQDs photocatalyst under visible light

In this paper, H-mSiO2-BiOI/CQDs hybrid materials were synthesized successfully via a facile method. Afterwards, the structures, morphologies, optical properties and photocatalytic performances of the prepared materials were investigated by multiple techniques. This research showed that the H-mSiO2-BiOI/CQDs materials demonstrated obviously improved photocatalytic performance compared with BiOI. In the photocatalysis process of rhodamine B (RhB) under visible light irradiation, the optimum photocatalytic performance would be obtained when the content of BiOI and the weight percentage of CQDs was appropriate. In this photocatalytic system, the enhanced photoactivity was mainly attributed to the synergistic effects of the huge BET surface area of H-mSiO2, multiple reflections of the internal cavities of H-mSiO2, facilitation of the reactant molecules transfer, efficient e−-h+ pair separation via CQDs, and the up-converted PL property of CQDs. The radical trapping experiments revealed that O2•−, e− and h+ were the main active species during the photocatalysis process. A possible mechanism of H-mSiO2 and CQDs for the enhancement of visible light performance was proposed.