Enhancement Of Photoluminescence Intensity Research Articles

Photoluminescence Intensity Enhancement and Stability in CdTe/SiO2 Quantum Dots through Water Molecule Adsorption and Trap Passivation

Photoluminescence Intensity Enhancement and Stability in CdTe/SiO2 Quantum Dots through Water Molecule Adsorption and Trap Passivation

Synergy of photoluminescence emission and antibacterial activity of Ag-Cu2O nanocomposite

Conglomerate nanocomposites comprising metal and metal oxide hold significant potential for exhibiting properties that surpass the combined characteristics of their individual components, owing to the interactions occurring at the interfaces between the metal and metal oxide elements. In this study, we present the synthesis of Cu2O nanoparticles (NPs) (with diameters ranging from 40 to 53 nm) and Ag-Cu2O nanocomposites using an aqueous solution method at room temperature, employing varying concentrations of Ag NPs. Through optical absorption studies, we determined the optical band gap of Cu2O NPs in 0.5Ag-Cu2O, 1Ag-Cu2O, and 1.5Ag-Cu2O nanocomposites samples to be 2.13 eV, 2.25 eV, 2.34 eV, and 2.41 eV, respectively. The x-ray diffraction data are analysed using the Williamson–Hall technique and revealed noteworthy variations in microstructural characteristics such as strain and stress within the Cu2O nanocrystallites fabricated under different Ag concentrations. The nanocomposites amplified the intensities of violet-blue, blue, and green photoluminescence (PL) emissions, attributable to the interfaces between Ag and Cu2O, lattice mismatches, and the induced microstructural parameters lattice strain, and stress of Cu2O nanocrystallites. The enhanced PL intensities can be attributed to the influence of the local electric field on the Ag core composites. The Ag-Cu2O nanostructure exhibits potential applications in water purification technologies, while the PL emission properties and low band gap (∼2.13 eV) hold promising applications in optoelectronic devices. The antibacterial activities of Cu2O and Ag-Cu2O nanomaterials against Enterococcus faecalis and Escherichia fergusonii are examined using MH agar well plate diffusion methods. Here, Ag NPs enhance bactericidal effectiveness through enhanced interaction with bacteria and the release of Ag+ ions, while the Cu2O shell discontinuity on Ag NPs contributes to their unique antibacterial properties.

Surface plasmon-mediated photoluminescence boost in graphene-covered CsPbBr3 quantum dots

The optical properties of graphene (Gr)-covered CsPbBr3 quantum dots (QDs) were investigated using micro-photoluminescence spectroscopy, revealing a remarkable three orders of magnitude enhancement in photoluminescence (PL) intensity compared to bare CsPbBr3 QDs. To elucidate the underlying mechanisms, we combined experimental techniques with density functional theory (DFT) calculations. DFT simulations showed that the graphene layer generates interfacial electrostatic potential barriers when in contact with the CsPbBr3 surface, impeding carrier leakage from perovskite to graphene and enhancing radiative recombination. Additionally, graphene passivates CsPbBr3 surface defect states, suppressing nonradiative recombination of photo-generated carriers. Our study also revealed that graphene becomes n-doped upon contact with CsPbBr3 QDs, activating its plasmon mode. This mode resonantly couples with photo-generated excitons in the perovskite. The momentum mismatch between graphene plasmons and free-space photons is resolved through plasmon scattering at Gr/CsPbBr3 interface corrugations, facilitating the observed super-bright emission. These findings highlight the critical role of graphene as a top contact in dramatically enhancing CsPbBr3 QDs’ PL. Our work advances the understanding of graphene-perovskite interfaces and opens new avenues for designing high-efficiency optoelectronic devices. The multifaceted enhancement mechanisms uncovered provide valuable insights for future research in nanophotonics and materials science, potentially leading to breakthroughs in light-emitting technologies.

Bioinspired ultrathin photonic color convertors for highly efficient micro‐light‐emitting diodes

AbstractPixelated color convertor plays an immensely important role in next‐generation display technologies. However, the inherent randomness of light propagation within the convertor presents a formidable challenge to reconcile the huge contradiction between excitation and outcoupling. Here, we demonstrate a bioinspired photonic waveguide pixelated color convertor (BPW‐PCC) to realize directional excitation and outcoupling, which is inspired by an insect visual system. The lens array of BPW‐PCC enables a focusing photonic waveguide that guides the excitation light and converges it on colloidal quantum dots; the directional channel provides a splitting photonic waveguide to enhance the outcoupling of photoluminescence light. Consequently, the excitation and outcoupling efficiency can be simultaneously improved at this judiciously designed pixelated color convertor with a thickness of 50 μm. By this strategy, ultrathin BPW‐PCCs with 4.4‐fold enhanced photoluminescence intensity have been demonstrated in micro‐light‐emitting diode devices and achieved a record‐high luminous efficacy of 1600 lm W−1 mm−1, opening a new avenue for efficient miniaturized displays.

Effect of Ga/Al ratio on the luminescent properties of inorganic scintillating GGAG:(4 mol%)Ce ceramic powder

Gadolinium gallium aluminum garnet doped with cerium (GGAG:Ce), a promising ceramic scintillator material, is being excessively explored for its high quality optical properties by the bandgap engineering with different Ga/Al ratio. In this study, GGAG:Ce powders were synthesized using a solvothermal method and sintered at 1300 °C to investigate the impact of the gallium-to-aluminum (Ga/Al) ratio on optical characteristics. The results revealed that a decrease in the Ga/Al ratio led to a decrease in particle size. This observation can be attributed to the different reactivity and growth kinetics of gallium and aluminum precursors during the solvothermal process. Perturbations from the optimized Ga/Al ratio of 1.5–1.77 and 1.27 resulted in substantially enhanced photoluminescence (PL) and radioluminescence (RL) spectra intensities. PL lifetime measurements of various Ga/Al ratio exhibit average PL lifetime between 48 and 57 ns. Specifically, the deviations to 1.77 and 1.27 ratios yielded approximately 125 % and 106 %, respectively, in observed luminescent measurements compared to other ratios. This enhancement in PL and RL intensity suggests that the Ga/Al ratio plays a critical role in modulating the optical properties of GGAG:Ce ceramic powders. The results of this study also highlight the importance of the Ga/Al ratio in tailoring the optical or luminescence characteristics of GGAG:Ce powders.

Multimodal optical detection, identification and reduction of Cr(VI) with carbon dots and its PVA/polyNIPAM spheres based 2D luminescent photonic structures

Multiple emissive carbon dots (CDs) were synthesized through a one-step solvothermal acid-assisted method using citric acid and urea. Three main emission bands were observed at ∼431 nm, ∼501 nm, and ∼622 nm, corresponding to excitation wavelengths of 360 nm, 430 nm, and 550 nm, respectively. Simultaneous detection through salient discernible features of three metal ions has been achieved. Emission of CDs with Fe(III) shows reduction in intensity at 360 nm and 550 nm wavelengths and an enhancement of photoluminescence (PL) intensity at an excitation wavelength of 430 nm. Al(III) revealed turn-on PL signals, along with a redshift when excited at 360 and 430 nm, and turn-off intensity at excitation of 550 nm. Under all the excitation wavelengths, Cr(VI) exhibits PL quenching accompanied with an additional red shift. This sensor enhances the accuracy and reliability of the probe through multiple distinctive and characteristic responses for all the three ions for which the probes were selective. Apart from the optical detection at a certain wavelength, the Cr(VI) reduction to the less toxic Cr(III) through as-prepared CDs could be monitored at three different excitation wavelengths. The Fe(III) and Cr(VI) detection in solid state has also been demonstrated through 2D luminescent photonic structures formed with CDs-PVA (poly-vinyl alcohol)-polyNIPAM (poly (N-isopropylacrylamide)) composites that can possibly be used for anticounterfeiting applications.

Investigation of the growth rate on optical and crystal quality of InGaAs/AlGaAs multi-quantum wells and InGaAs single layer grown by molecular beam epitaxy (MBE)

The impact of growth rate on the optical and crystal quality of InGaAs/AlGaAs multi-quantum wells (MQWs) and InGaAs single layer grown by molecular beam epitaxy (MBE) is studied. Photoluminescence (PL) and high-resolution X-ray diffraction (HRXRD) are applied for evaluation of the optical, crystal quality and interfaces smoothness. The room-temperature PL integral intensity increases by 220 % when the growth rate decreases from 2 to 1 Å/s. HRXRD analysis reveals the growth rate of 1 Å/s improves crystal and interface quality of MQWs, as well as significantly enhances PL intensity. But further reduce growth rate to 0.5 Å/s, the PL integral intensity decreases, instead. At lower growth rate, more impurities can incorporate into InGaN layer and act as nonradiative recombination centers. Growth rate can effectively control crystal quality, interfaces smoothness and impurity content and thus determine the optical quality of InGaAs/AlGaAs MQWs.

Influence of carbon dots integrated in Pr3+ doped gahnite nanophosphor for thermal sensing, data fortification and fingerprint visualization analysis through YOLOv8x deep learning embedded model

The remarkable optical properties of carbon dots (CDs) render them highly promising as a versatile group of carbon-based nanomaterials. Integrating hydrothermally synthesized CDs into zinc aluminate doped with Pr3+ ions (ZnAl2O4:Pr3+) nanophosphors (ZAO:Pr3+ NPs) fabricated via the solution combustion (SC) technique holds great potential. The aim of synthesizing these nanocrystals (NCs) is to explore their potential uses in optical thermometry and anti-counterfeiting (AC) measures. The synthesized nanoparticles (NPs) and nanocomposites (NCs) underwent characterization using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectra to verify their phase, morphology, particle size, oxidation state, and chemical composition. When excited at 447 nm, the Pr3+ doped ZAO: NPs exhibited an orange-red emission band at 614 nm. A remarkable enhancement in PL intensity, by a factor of 39.02 folds, is noted upon embedding CDs into the ZAO:Pr3+ NPs (CDs@ ZAO:Pr3+). The enhanced PL intensity can be ascribed to the Förster resonance energy transfer (FRET) mechanism. Even at a temperature of 423 K, the NPs retains 95.4% of its emission intensity compared to that at room temperature, showcasing exceptional thermal stability. The 5 wt% CDs@ZAO:1Pr3+ NCs demonstrate a high colour purity (CP) of 98.3%. Moreover, these NCs hold promise for optical thermometry applications across a broad temperature range spanning from 303 to 463 K. Utilizing the exceptional ZAO:1Pr3+ NPs and 5 wt% CDs@ZAO:1Pr3+ NCs, two representative white light emitting diodes (w-LEDs) have been successfully developed, boasting satisfactory luminous efficacy and colour-rendering index (CRI). This underscores their potential for high-performance w-LED applications. Simultaneously, a highly sensitive, non-contact optical thermometer has been engineered, featuring maximum relative sensitivities of approximately 44.51×10−4K−1 and 75.48×10−4K−1 at the emission intensities corresponding to 673, 693, 712 and 735 nm, respectively. We have developed a simple brush mode technique for creating a variety of patterns using the manufactured AC security ink. The latent fingerprints (LFPs) visualized using 5 wt% CDs@ZAO:1Pr3+ NCs exhibit excellent resolution and contrast, enabling the easy identification of fingerprint characteristics from levels I-III. Employing deep learning utilizing the YOLOv8x algorithm, fluorescence images of the revealed LFPs demonstrate remarkable alignment with standard controls, suggesting a high degree of similarity. In addition, the fabricated white light emitting diode (w-LED) boasts a favorable colour rendering index (Ra=87) alongside Commission International de L′Eclairage (CIE) coordinates (0.617, 0.376). Consequently, the inclusion of 5wt% CDs@ZAO:1Pr3+NPs showcases remarkable luminescent attributes and holds promising prospects across various applications.

New graphene oxide doped polymer dispersed liquid crystal nanocomposites targeted to eco-friendly and energy-efficient smart windows

Graphene oxide-polymer dispersed liquid crystal (GO-PDLC) composites are proposed as a solution for energy-efficient switchable windows. These composites were prepared by incorporating varying concentrations of graphene oxide (GO) into a mixture of nematic liquid crystal (E7) and a UV–Vis curable resin using the polymerization-induced phase separation technique. The results indicate that the dispersion of GO at an optimum concentration of 0.005 wt% significantly affects the morphology, phase transition temperatures, and electro-optic properties of polymer dispersed liquid crystal (PDLC). In particular, the GO-PDLC composites exhibit a transition from an opaque to a transparent state at a remarkably low voltage (∼11.5 V) compared to pure PDLC cell. Dielectric analysis reveals that adding GO increases the permittivity, conductivity, and dielectric strength of PDLC composites. Moreover, the Cole-Cole plot indicates a non-Debye type relaxation in a higher frequency region. Furthermore, a blue shift in emission wavelength and enhanced photoluminescence intensity suggest alterations in electronic transitions within the composites. This comprehensive study provides valuable insights into optimizing the properties of PDLCs through the dispersion of GO, thereby offering promising prospects for their utilization in various optoelectronic applications.

Luminescent carbon dots encapsulating in Eu3+ doped gahnite spinel nanocomposite for boosting thermal sensing, advanced level III detection and intelligent anti-counterfeiting applications

The exceptional optical properties of carbon dots (CDs) position them as a highly promising category of multifunctional carbon-based nanomaterials. When hydrothermally prepared CDs are incorporated into europium-doped zinc aluminate ZnAl2O4 nanophosphors (ZAO:Eu3+ NPs) synthesized via ultrasonication method, the resulting CDs@ZAO:Eu3+ nanocomposite (NCs) exhibits a broad excitation band, with a prominent peak at approximately 393 nm, perfectly matching the emission wavelength range (500–750 nm) of near-ultraviolet (n-UV) LED chips. Significantly, the CDs (5 wt %)@ZAO:Eu3+ NCs exhibit a remarkable 12.5 folds enhancement in photoluminescence (PL) intensity compared to ZAO:Eu3+ alone, thanks to the Förster Resonance Energy Transfer (FRET) between CDs and Eu3+ ions. This enhancement in luminescence could stem from the CDs capturing electrons and facilitating energy transfer to the luminescent Eu3+ ions. Utilizing CDs to enhance fluorescence presents a straightforward and eco-friendly approach for boosting luminescence properties. Impressively, even under elevated temperatures reaching 420 K, the thermal stability of CDs (5 wt %)@ZAO:Eu3+ NCs remains outstanding, retaining 90 % of its initial luminescence intensity. This highlights its exceptional thermal stability, characterized by a high activation energy of 0.27 eV. With an impressive internal quantum efficiency (IQE) of 87.01 %, the optimized composite also achieves remarkable colour purity (CP), reaching 99.5 %. The relative sensitivity was 1.36 %, at 300 K. Thus, CDs@ZAO:Eu3+ is a promising material for non-contact optical thermometry applications. Utilizing the optimized NCs through a simple powder dusting technique effectively develops latent fingerprints (LFPs) on various surfaces, revealing fingerprints (FPs) under 365 nm UV light. Additionally, the study investigates diverse pore parameters including number, position, size, shape, and inter-spacing. Furthermore, optimized NCs are utilized to create a transparent anti-counterfeiting (AC) ink, offering effective AC features through its red emission under 365 nm UV light.

Enhanced Spontaneous Emission through High‐k Modes in CsPbBr3 Perovskite Hyperbolic Metamaterials

AbstractNovel optical sources require fast decay rates, making hyperbolic metamaterials (HMMs) an increasingly attractive option. HMMs are well‐known for their remarkable anisotropy, and leverage hyperbolic dispersion to enhance the decay rate of a fluorophore placed on top of them. This study tackles the complex task of embedding a fluorophore into an HMM, successfully overcoming challenges related to surface roughness, thickness imperfections, and layer washing effects. Specifically, CsPbBr3 perovskite nanocrystals (NCs)‐based HMM are fabricated, by alternating silver/nanocrystals (Ag/NCs) layers. Through a systematic investigation of the photophysical response following the deposition of each bilayer, compelling evidence of the achievement of hyperbolic dispersion is provided. Specifically, the impact of “high‐k” modes is isolated, which is distinctive to the HMM architecture. Therefore, the longstanding debate regarding the number of bilayers needed to achieve hyperbolic dispersion is conclusively resolved. The research demonstrates a nearly twofold increase in the decay rate and a threefold enhancement in photoluminescence intensity. These findings are further supported by theoretical Purcell factor calculations. This study marks a pioneering advancement in the field of bulk dye‐embedded HMMs, laying the groundwork for the development of advanced optical sources such as “resonant gain HMMs”.

Stable FAPbI3 Perovskite Solar Cells via Alkylammonium Chloride-Mediated Crystallization Control.

α-Phase formamidinium lead iodide (FAPbI3) perovskite solar cells (PSCs) have garnered significant attention, owing to their remarkable efficiency. Methylammonium chloride (MACl), a common additive, is used to control the crystallization of FAPbI3, thereby facilitating the formation of the photoactive α-phase. However, MACl's high volatility raises concerns regarding its stability and potential impact on the stability of the device. In this study, we partially substituted MACl with n-propylammonium chloride (PACl), which has a long alkyl chain, to promote the oriented crystallization of FAPbI3, ultimately forming an δ-phase-free perovskite. The FAPbI3 film containing PACl demonstrates an enhanced photoluminescence intensity and lifetime. Additionally, PACl's presence at grain boundaries acts as a protective layer for the PSCs. Consequently, we achieved a power conversion efficiency (PCE) of 22.4% and exceptional stability. It maintains over 95% of initial PCE for 100 days in an N2 glovebox, over 85% after 100 h of maximum power point tracking, and over 80% after 60 °C thermal aging.

Effect of DC poling on transparency and photoluminescence in Pr:PMN-PT transparent ceramics

Electric poling could significantly influence the transparency and the photoluminescence (PL) intensities in transparent ferroelectric PL ceramics. This work applied direct current (DC) poling on a highly transparent 0.75PMN-0.25PT:0.015Pr3+ ceramic, observed the domain configurations in a direction perpendicular to poling direction. Lamellar domains perpendicular to electric field were observed after poling and decreased the transmittance by changing the propagation path of incident light. Besides, the enhancement of PL intensities by poling was found as high as 62 %, mainly due to the following reasons: the change of light propagation path by the lamellar domains is supposed to increase the absorption of exciting light; and the reduced crystal symmetry may increase the PL efficiency. This work revealed the effects of DC poling on transparency and PL properties in transparent ferroelectric PL ceramics.

Unraveling Exciton-Plasmon Coupling and the PIRET Mechanism in Decorated Silicon Nanowires.

Exciton-plasmon coupling is a fascinating physical phenomenon that has been investigated in various metal semiconductor systems. Intentionally chosen silicon nanowires (SiNWs) systems act as a host material for providing exciton as well as silicon oxide as a thin dielectric. A clear blue-shift in photoluminescence (PL) peak and a significant increase in visible range absorption were observed for metal nanoparticle (MNP) decorated SiNWs (D-SiNWs) which signifies the presence of exciton-plasmon coupling. A further investigation reveals that the possibility of the occurrence of the plasmon-induced resonance energy transfer (PIRET) mechanism is higher. The PL intensity enhancement in Au-decorated SiNWs is higher (∼38 times) in comparison to that in Pt due to the presence of a strong and localized electric field of plasmons near the interface of metal and semiconductors. Moreover, splitting in PL for gold-decorated SiNWs might be due to the presence of dipole-quadrupole coupling along with dipole-dipole coupling, which further increases the strength of the PIRET mechanism.

Static and dynamic strain-driven photoluminescence tuning in rare-earth doped perovskite oxide thin films

Recently, there have been significant interest in the wide potential of photoluminescence (PL) response of rare-earth doped perovskite oxide thin films in the field of optoelectronics. This work reports an effective method to modulate the PL properties of 0.8 mol%Sm3+-doped BaTiO3 (BTO:Sm) thin films through static and dynamic strain. BTO:Sm films were epitaxially grown on LaAlO3 (LAO), 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT), MgO, and Mica single-crystal substrates by pulsed laser deposition technique. Compared with the BTO:Sm/PMN-PT heterostructure which experiences minimal lattice mismatch effect, the PL intensity of BTO:Sm/LAO and BTO:Sm/MgO is enhanced by 818.1% and 1014.7%, respectively, due to static tensile/compressive strain (-0.429% and 0.461%) during the epitaxial growth process. In the flexible BTO:Sm/Mica heterostructure, dynamic strain is introduced through mechanical bending. Compared with the unbent state, the u-type and n-type bending modes increase the relative changes in PL intensity (ΔI/I) by 599.0% and 768.5%, respectively. Particularly, BTO:Sm/Mica also exhibits a remarkable optical transmittance exceeding 75% (500–2500 nm). The enhancement of PL intensity is closely related to the adjustment of lattice strain, which changes the crystal field strength of the BTO:Sm and the radiative transition probability. This work provides valuable insights for designing future optoelectronic devices and environmental monitoring equipment. It has the potential to advance photonics and sensor technologies, paving the way for innovation and exploration in these fields.

Study of structural and optical properties of Gd doped ZnO nanostructures synthesized by one-step, mass-scale productive method

In the present work, one-step, mass-scale productive solid state reaction method has been employed for the preparation of gadolinium (Gd) doped ZnO (GZOx: x = 0, 2, 4, 6, 8 wt%) nanostructures. The prepared GZOx samples have been studies their structural, morphological, elemental diffusion profile and optical properties using P-XRD, FE-SEM, EDS, FTIR, and photoluminescence (PL) spectroscopy. The powder X-ray diffractometer (P-XRD) results clearly indicate strong and sharp diffraction peaks with broadening that confirms the formation of hexagonal nanocrystalline structure of ZnO and Gd doped ZnO. The hexagonal morphology formation of the grains after doping of Gd contents into the ZnO nanostructures system is seen from the FE-SEM micrographs and the sizes of the grains are found to close to the results obtained from XRD patterns. The presence of Gd contents in ZnO matrix confirms its doping by EDS spectrum of 4 wt% Gd doped ZnO nanostructures. Fourier transform infrared (FTIR) results confirm the presence of functional groups and chemical bonding of ZnO at room temperature. Investigation of optical emission is interesting and the PL spectra reveal two emission peaks, one in UV-region located in the range of ∼385 to 395 nm and other is defects related emission centred at ∼450, ∼468, ∼503 and ∼562 nm in visible region for all the samples. The enhanced PL intensity is observed in the higher doped Gd contents in ZnO nanostructures and can be attributed to the presence of Gd ions into ZnO lattice. The detailed structural and luminescence analysis has been carried out and correlated. The study of structural and optical properties GZOx samples suggest the luminescent optoelectronic applications.

Compositional Transformation and Impurity‐Mediated Optical Transitions in Co‐Evaporated Cu2AgBiI6 Thin Films for Photovoltaic Applications

AbstractQuaternary copper‐silver‐bismuth‐iodide compounds represent a promising new class of wide‐bandgap (2 eV) semiconductors for photovoltaic and photodetector applications. In this study, vapor phase co‐evaporation is utilized to fabricate Cu2AgBiI6 thin films and photovoltaic devices. The findings show that the properties of vapor‐deposited films are highly dependent upon processing temperature, exhibiting increased pinhole density and transforming into a mixture of quaternary, binary, and metallic phases depending on the post‐deposition annealing temperature. This change in phase is accompanied by an enhancement in photoluminescence (PL) intensity and charge‐carrier lifetime, along with the emergence of an additional absorption peak at high energy (≈3 eV). Generally, increased PL is a desirable property for a solar absorber material, but this change in PL is ascribed to the formation of CuI impurity domains, whose defect‐mediated optical transition dominates the emission properties of the thin film. Via optical pump terahertz probe spectroscopy, it is revealed that CuI impurities hinder charge‐carrier transport in Cu2AgBiI6 thin films. It is also revealed that the predominant performance limitation in Cu2AgBiI6 materials is the short electron‐diffusion length. Overall, the findings pave the way for potential solutions to critical issues in copper‐silver‐bismuth‐iodide materials and indicate strategies to develop environmentally compatible wide‐bandgap semiconductors.

Rapid PL Enhancement in Cd doped Alq3 Nanowires

Aluminium tris (8-hydroxyquinoline) (Alq3) is a popular coordination complex extensively used in organic luminescent devices as the emissive layer. Metal doping in Alq3 and its nanoscale synthesis are two strategies which are widely adopted to enhance the functional properties of Alq3. In the present work, Cadmium (Cd) doped Alq3 films having 1-dimensional morphology have been successfully synthesised using thermal vapor transport method. These films have been subjected to different analytical studies to study their functional properties. Scanning Electron Microscopy (SEM) images reveal the dendritic nature of Cd-doped Alq3 nanowires while Energy Dispersive X-ray Spectroscopy (EDAX) analysis confirms the presence of Cd in Cd-doped Alq3 nanowires. X-ray Diffraction (XRD) study reveals the polycrystalline nature of Cd-doped Alq3 nanowires. X-ray Photoelectron Spectroscopy (XPS) analysis of Cd-doped Alq3 nanowires samples indicates the replacement of some Al atoms with Cd atoms in Alq3 matrix. UV–visible spectroscopy study of the Cd-doped Alq3 nanowires shows enhancement in the optical absorbance with increasing Cd concentration while Photoluminescence (PL) spectroscopy analysis shows a 7-fold enhancement in PL intensity for 0.5 mol% Cd-doping. This rapid enhancement in the PL is explained on the basis of electronic charge transfer from Cd ions to Alq3 molecules.

Enhancement of Optical Properties and Stability in CsPbBr3 Using CQD and TOP Doping for Solar Cell Applications

Cesium lead bromide (CsPbBr3) nanocrystals exhibit remarkable optoelectronic properties and exceptional stability. As a result, they have garnered significant interest for their potential applications in various fields, including solar cells, light-emitting devices, photodetectors, and lasers. Despite its resistance to moisture, oxygen, and heat compared to other perovskite materials, CsPbBr3 still faces challenges maintaining its structural and optical stability over extended periods. This study proposes a robust solution to enhance and improve simultaneously the photoluminescence intensity and stability of CsPbBr3 nanocrystals. The solution involves doping the perovskite precursor with green-synthesized carbon quantum dots (CQDs) and tri-n-octyl phosphine (TOP). The results indicate that the photoluminescence intensity of the perovskite nanocrystals (NCs) is sensitive to varying CQD ratios. A high photoluminescence intensity enhancement of 45% was achieved at the optimal CQDs ratio. The synthesized perovskite NCs/CQDs also demonstrated improved stability by adding TOP into the mixture. After storage in the air for 45 days, the mixed perovskite NCs maintained their performance, which was almost unchanged. Solar cell devices based on the modified perovskite NCs showed a power conversion of 7.74%. The devices also demonstrated a significant open-circuit voltage (VOC), with the most successful device achieving a VOC of 1.193 V, an Isc of 10.5748 mA cm−2, and a fill factor (FF) of 61%. This study introduces a cost-effective method for producing high-quality all-inorganic optoelectronic devices with enhanced performance and stability.

Conjugated polymer-perovskite quantum dot (MDMO-PPV:CsPbBr3) nanocomposites: Miscibility, nano-structures, and properties

All-inorganic cesium lead bromide (CsPbBr3) quantum dots (QDs) have received a surge of attention in the field of light-emitting diode (LED) display and lighting. Hence, it is interesting to study the composite film composed of CsPbBr3 and light-emitting MDMO-PPV matrix polymer. In this study, we investigate the phase behavior among the components, MDMO-PPV, toluene (solvent), and oleic acid and oleylamine (the surface ligands for QDs) based on the Flory-Huggins theory with the group contribution method for the first time. Here we find that the MDMO-PPV and ligand molecules are immiscible whereas MDMO-PPV and toluene are partially miscible. Then through the x-ray diffraction (XRD) patterns, we demonstrate that CsPbBr3 QDs form a nanoscale domain with ∼33–52 nm crystallites in the MDMO-PPV matrix. Furthermore, the scanning electron microscope (SEM) images display that CsPbBr3 QDs can be highly aggregated at MDMO-PPV:CsPbBr3= 50:50 composition. Then, through the ultraviolet-visible (UV–vis) and photoluminescence (PL) spectra, the enhancement of PL intensity is observed at ∼30–50 wt% CsPbBr3. Finally, the electrochemical impedance spectra indicate that the composite film exhibits less resistance (∼3.2×104 Ω) than the pure MDMO-PPV film (∼1.4×107 Ω), suggesting that the MDMO-PPVCsPbBr3 composite approach is promising for electrochemical and optoelectronic applications.