Optical Behavior Research Articles

Impact of the host lattice on crystallographic, Raman, optical, and luminescent properties on the terbium ion

AbstractA comparative study of the Gd2O3:Tb and Y2O3:Tb nanoparticles (NPs) was presented to examine the influence of the host lattices on the crystallographic phase, surface characteristics, optical properties, Raman effect, and photoluminescence properties. Cubic shapes Gd2O3:Tb and Y2O3:Tb NPs with an estimated crystalline size of 17 and 11 nm were recorded from the X‐ray diffraction pattern, respectively. Comparative absorption spectra of both oxides NPs were presented to examine the dispersibility, colloidal stability, and optical behavior of the NPs. Energy bandgap values were estimated to monitor the optical characteristics of the metal oxides in the UV/Vis region. Fourier transform infrared was recorded to confirm the surface‐attached water and organic moieties. The Raman spectra of metal oxides were recorded to examine the symmetrical dis‐order and polarizability of the vibrational bands. The ionic radius of the atoms distorts the bond structure resulting in it greatly influenced the vibrational bands of the materials. The emission spectra certified the effective doping of the luminescent Tb3+‐ion in the metal oxide host lattices. Raman spectra and emission spectra validated the crystal symmetry imperfections; subsequently, the efficiency of the Raman active modes and emission transitions was greatly influenced. In a comparative analysis, Y2O3:Tb NPs exhibited higher luminescence intensity in comparison with the Gd2O3:Tb NPs.

Transient Optical Modulation in Vanadium and Selenium Doped MoS2 by Carrier–Carrier and Carrier–Phonon Interactions

AbstractDoping and alloying induce defect states in atomically thin transition metal dichalcogenides (TMDCs), leading to strong carrier–phonon interactions. The robust excitonic behavior of these layered materials can be modified by injecting a high density of charge carriers. However, comprehending the influence of carrier–phonon and carrier–carrier interactions on the optical properties of 2D materials is crucial for their optoelectronic and photonic applications. Here, transient absorption (TA) spectroscopy is employed to demonstrate the modulation of the transient optical behavior of TMDCs through doping and excitation near Mott density. The TA spectra reveal broadening attributed to carrier–carrier and carrier–phonon interactions, with the broadening being particularly pronounced in vanadium (V) doped TMDCs due to the hybridization of defect and exciton transitions. Analysis of TA kinetics suggests the involvement of various carrier species in the carrier dynamics of TMDCs, with the influence of mid‐gap carriers dominating at higher excitation densities. Nonetheless, the presence of strong carrier–phonon coupling in V‐doped TMDCs is demonstrated by temperature‐dependent Raman and photoluminescence spectroscopy. The results reveal that the enhanced coupling between acoustic phonons and carriers can lead to multiphonon emission. The findings of this study hold promise for controlling the optical response of TMDCs in ultrafast optoelectronic applications.

In Situ Solid-State Dewetting of Ag-Au-Pd Alloy: From Macro- to Nanoscale.

Metal alloy nanostructures represent a promising platform for next-generation nanophotonic devices, surpassing the limitations of pure metals by offering additional "buttons" for tailoring their optical properties by compositional variations. While alloyed nanoparticles hold great potential, their scalability and underexplored optical behavior still limit their application. Here, we establish a systematic approach to quantifying the unique optical behavior of the AgAuPd ternary system while providing a direct comparison with its pure constituent metals. Computationally, we analyze their electronic structure and uncover the transition of Pd d states to Pd/Ag hybridized s states in the bulk form, explaining the similar optical properties observed between Pd and AgAuPd. Experimentally, we fabricate pure metal and fully alloyed nanoparticles through solid-state dewetting, a scalable method. During the process, we trace the optical transition in the systems from the initial thin film stage to the final nanoparticle stage with in situ ellipsometry. We reveal the interplay between optical properties influenced by chemical interdiffusion and localized surface plasmon resonance arising from morphological changes with ex situ surface characterizations. Additionally, we analytically implement a metallic layer derived from the ternary system in a trilayer device, resulting in a single-time and irreversible color filter, to demonstrate an application encompassing a lithography-free and cost-effective route for nanophotonic devices.

Application of Sound Waves During the Curing of an Acrylic Resin and Its Composites Based on Short Carbon Fibers and Carbon Nanofibers

Research into particulate polymer composites is of significant interest due to their potential for enhancing material properties, such as strength, thermal stability, and conductivity while maintaining low weight and cost. Among the various techniques for preparing particle-based composites, ultrasonic wave stimulation is one of the principal laboratory-scale methods for enhancing the dispersion of the discontinuous phase. Nevertheless, there is a scarcity of empirical evidence to substantiate the impact of stimulating materials with natural sound frequencies within the acoustic spectrum, ranging from 20 Hz to 20 kHz, during their formation process. The present work investigates the effect of acoustic stimuli with frequencies of 56, 111, and 180 Hz on the properties of an acrylic-based polymer and its discontinuous carbon-based composites. The results indicated that the stimulus frequency affects the cure time of the studied systems, with a notable reduction of 31% and 21% in the cure times of the neat polymer and carbon-nanofiber-based composites, respectively, after applying a frequency of 180 Hz. Additionally, the higher stimulation frequencies reduced porosity in the samples, increased the degree of dispersion of the discontinuous phase, and altered the composite materials’ thermal, optical, and electrical behavior.

Effect of Titanium Oxide (TiO2) Nanoparticles on the Opto-Mechanical Properties of Polyethylene Terephthalate (PET) Fibers

Polyethylene terephthalate (PET) is widely used in various applications due to its excellent mechanical properties and chemical resistance. However, PET fibers still lack specific features and functionalities that can be improved via nano-additives, particularly metal oxides. In this study, we investigate the effect of adding TiO2 nanoparticles to PET to form PET/TiO2 fibers and examine their opto-mechanical properties. This study utilizes optical interferometric techniques to assess how mechanical stretching influences the optical and mechanical properties of PET fibers treated with TiO2 nanoparticles. A Mach–Zehnder interferometric setup, integrated with a versatile device capable of mechanically stretching samples, is used to achieve this task. Variations in refractive index and birefringence along the longitudinal axis of undrawn and drawn PET/TiO2 fibers are examined. The research meticulously explores the fluctuations and spatial variations in the refractive index and birefringence properties, exhibiting anisotropy in optical behavior, along the longitudinal axis of unstretched and stretched PET/TiO2 fibers. The findings and outcomes derived from this comprehensive study provide substantive information that can facilitate the enhancement and optimization of the coupled optical and mechanical properties of materials explicitly engineered for advanced applications.

Unusual Optical, Electric, and Magnetic Behaviors of OLEDs due to Exothermic/Endothermic Dexter-Energy-Transfer and Fusion Channels of Hot/Cold Triplet Excitons

Unusual Optical, Electric, and Magnetic Behaviors of OLEDs due to Exothermic/Endothermic Dexter-Energy-Transfer and Fusion Channels of Hot/Cold Triplet Excitons

Characterization of 3D printed composite for final dental restorations.

This study evaluated the mechanical, optical, microstructural, surface, and adhesive behavior of a 3D printing resin comparing it with a machinable resin composite. Specimens of different sizes and shapes were either printed (Vitality, Smart Dent) or machinable (Grandio Blocs, Voco GmbH) resin composites with similar composition were prepared. Surface and mechanical characterization were performed with Knoop hardness, flexural strength (three-point-bending), and elastic modulus tests. The wear of the tested materials was evaluated against steatite antagonists. The optical properties stability (color change, ΔE00, and translucency, TP00) were observed after staining in red wine. In addition, the bond strength of the resin composites to two resin cement protocols were investigated with microshear bond strength tests at baseline and after thermocycling. Scanning electron microscope (SEM) coupled with Energy-Dispersive X-ray Spectroscopy (EDS) was used for microstructural and chemical characterization. Statistical analyses were performed with t- and ANOVA tests. Hardness values (132.76 (16.32) KH- Machinable and 35.87 (2.78) KH - Printed), flexural strength (172.17 (26.99) MPa - Machinable and 88.69 (8.39) MPa - Printed), color and translucency change (1.86 (0.31)/0.06 - Machinable and 3.73 (0.36)/9,16- Printed), and wear depth (24.97mm (3.60)- Machinable and 7.16mm (2.84) - Printed) were statistically different. Average Regarding bond strength, mean values (MPa) for non-aged and aged groups were respectively 21.76 (6.64) / 31.9 (12.66) for Bifix cement (Voco GmbH, Cuxhaven, Germany) and 26.75 (5.14) / 24.36 (6.85) for Variolink cement (Ivoclar Vivadent, Schaan, Liechtenstein) in Printed and 17.79 (3.89) / 9.01 (3.36) ) for Bifix cement and 22.09 (6.55) / 11.01 (3.77) for Variolink cement in Machinable materials. The material and aging factors did affect bond strength but the cement factor did not (p = 0.202). No statistical differences were observed for mean roughness (Ra) between materials. The better dispersion and larger size of the inorganic particles in the Machinable resin were contrasted with the clustered smaller particles of printed resin, under SEM. The mechanical properties and color stability of the machinable resin were superior to those of the printed resin, probably due to the greater amount and dispersion of inorganic particles in the Mach resin, but bond strength after aging was stronger and more stable in the printed resin. 3D-printed resin composites with similar compositions to machinable resin composites do not necessarily exhibit the same properties, which can impact clinical performance. Understanding these differences can assist manufacturers in improving their materials and help clinicians distinguish between materials appropriate for provisional and final restorations.

Holographic multiplexing metasurface with twisted diffractive neural network

As the cornerstone of AI generated content, data drives human-machine interaction and is essential for developing sophisticated deep learning agents. Nevertheless, the associated data storage poses a formidable challenge from conventional energy-intensive planar storage, high maintenance cost, and the susceptibility to electromagnetic interference. In this work, we introduce the concept of metasurface disk, meta-disk, to expand the capacity limits of optical holographic storage by leveraging uncorrelated structural twist. We develop a physical twisted neural network to describe the optical behavior of the meta-disk and conduct a comprehensive lateral error analysis, where the meta-disk stores large volumes of information through internal structural multiplexing. Two-layer 640 µm x 640 µm meta-disk is sufficient to store over hundreds of high-fidelity images with SSIM of 0.8. By harnessing advanced three-dimensional (3D) printing technology, optical holographic storage is experimentally demonstrated with Pancharatnam-Berry metasurfaces. Our technology provides essential backing for the next generation of optical storage, display, encryption, and multifunctional optical analog computing.

Modification of opto‐electrical behavior of polyvinyl chloride by infusion of SrTiO3 nanofiller synthesized via green route

AbstractEnhancing the opto‐electrical properties of polymer is crucial for optoelectronic devices. This study emphasis the synthesis of strontium titanate (SrTiO3) nanoparticles using a green sol–gel method and incorporates them into polyvinyl chloride (PVC) to create nanocomposite films via solution casting. The structural, optical, thermal, and electrical properties of PVC with SrTiO3 at concentrations of 1, 3, and 5 wt.% were examined. Better crystallinity was obtained with filler incorporation. Fourier transform infrared shows the physical interaction between nanofiller and the matrix. SEM results suggested that SrTiO3 nanofiller are well distributed in PVC surface. UV–Vis spectroscopy was used to study optical behavior of the nanocomposites. Optical bandgap energy decreased from 3.2 to 2.5 eV with increased concentration of SrTiO3 in PVC matrix. Photoluminescence results show the reduction of electron hole recombination rate. The integration of SrTiO3 nanofiller into the PVC matrix improved the thermal stability, dielectric constant, and the overall performance of the prepared nanocomposite films, making them suitable for high‐temperature optoelectronic and energy storage applications. The green synthesis of SrTiO3 nanofiller also ensures the environmental benefits, high purity, and homogeneity, leading to consistent enhancements in the PVC/SrTiO3 composites. These improvements highlight their potential for advanced optoelectronic devices requiring efficient and durable materials.

Strain effects on electronic structure and optics of al-Doped monolayer GaS

This comprehensive study utilises rigorous first-principles calculations to meticulously investigate the influence of uniaxial tensile strain on the electronic configuration and optical behaviours of aluminium-doped gallium sulphide. The study highlights the modulation of electrical properties and optical responses in Al-doped monolayer GaS through the application of tensile strain. Notably, with increasing tensile strain, the bandgap value of the pristine GaS exhibits a pronounced decline, whereas the Al-doped variant maintains a more stable bandgap. A deeper exploration of the state density reveals the emergence of novel electronic states and energy levels in both the pristine and Al-doped monolayer GaS systems as tensile strain is applied. Crucially, the stabilising effect of the doped Al atoms minimises variations in the state density profiles of the Al-doped monolayer GaS systems, in contrast to their pristine counterparts. This result implies that fine control of the electrical structure and optical characteristics of Al-doped monolayer GaS may be achieved by the application of uniaxial tensile strain. The optoelectronic characteristics of GaS and its doped systems are explained in detail by these discoveries, which also offer a crucial theoretical foundation and direction for the use of these materials in optoelectronic devices.

Physical and enhanced photocatalytic MO dye degradation behaviour of Zn doped β-Ga2O3 microrods

This work explored the effects of Zn doping on the structural, micrographic, optical and photocatalytic behaviour of gallium oxide (β-Ga2O3) microrods. The X-ray diffractogram (XRD) and Raman spectral analyses confirmed the monoclinic structure of β-Ga2O3, with a shift to lower angles in the XRD pattern indicating Zn incorporation into the Ga2O3 lattice. The Scanning electron microscopy (SEM) images revealed a rod-like shape, with the diameter decreasing from 604 nm to 573 nm with Zn doping. Further analysis using TEM, HR-TEM, SAED, EDX, and elemental mapping confirmed the shape, crystallinity, crystal structure, and elemental distribution. The interplanar spacings were measured as 0.4 and 0.2 nm, corresponding to the (002) and (−311) planes of β-Ga2O3. UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS) showed a slight shift in the absorption edge, while photoluminescence (PL) analysis demonstrated strong UV and weak visible light emission. Photocatalytic results revealed a high efficiency of dye degradation,(i.e) 98 % (20 ppm) and 89 % (30 ppm) against methyl orange (MO) dye aqueous solution over 150 min, with a rate constant of 0.02/min and 0.01/min, respectively for 1.5 wt% Zn doping. This suggests that the Zn-doped material holds promise as a photocatalyst for wastewater treatment applications.

New optical soliton solutions and dynamic behaviours analysis of the Sasa-Satsuma equation in optical fibers

This article investigates novel exact solutions of the Sasa-Satsuma equation for describing the nonlinear characteristics of pulse transmission in optical fiber communication. Various new exact solutions of the Sasa-Satsuma equation were derived employing both the ( G ′ G ′ + G + A ) expansion method and the Bernoulli ( G ′ G ) expansion method. To provide a more intuitive depiction of the optical solitons’ behaviour during transmission, we generated two-dimensional graphs, three-dimensional graphs, and contour maps corresponding to the solutions. These images enable us to showcase the dynamic behaviour of this theoretical model and delve into the specific influence of the self-steepening effect on the transmission characteristics of optical solitons described by the new exact solutions to the Sasa-Satsuma equation.

Cerium-infused tungstate nanocrystals: Illuminating the future of solid-state lighting

Rare earth based luminescent materials have emerged as a focal point of the scientific investigation owing to their remarkable optical behaviour and potential applications. An effort has been made to develop a series of Ce3+ doped CaWO4 nano-phosphors using an ethylene-glycol assisted reflux route. The detailed structural and morphological properties have been examined through various analytical techniques. The +3-oxidation state of the activator ion Ce has been verified through the XPS study. The change in optical band gap due to the substitution is well discussed using diffuse reflectance spectroscopy. In Photoluminescence study, a broad emission centred at 465 nm is observed due to the 5D3/2→2FJ transitions (J = 7/2 and 5/2) and a significant enhancement in the emission peak is obtained for the optimized phosphor. Concentration quenching phenomenon, observed after 3 mol% of Ce3+ is mainly mediated by the electric multipole-multipole type interaction. The CIE diagram indicates the tuning of emission colour from blue to white region and the emission near white region for the optimized phosphor is further authenticated by its low colour purity value (43 %). The effective tunability of photo-physical properties and colorimetric parameters suggest the applicability of the optimized nano-phosphor in solid state lighting especially for outdoor illumination.

Reversible photochromism and photoluminescence modulation in (K,Na)NbO3‐based ceramics via oxygen vacancy regulation

AbstractMost of the optical behaviors in photoelectric multifunctional ceramics strongly depend on the addition of rare‐earth elements. However, the limited species of rare‐earth cations available as luminescence centers restrict the further development of photoelectric devices. Additionally, introducing the large atomic‐radii elements usually dramatically deteriorates the piezoelectric properties. Herein, the novel photochromism and luminescence modulation properties have been realized in CuO‐doped [(K0.43Na0.57)0.94Li0.06][(Nb0.94Sb0.06)0.95Ta0.05]O3 (KNLNST) piezoelectric ceramics which show intense sensitivity to visible‐light irradiation. As a strategy for regulating oxygen vacancy concentrations in piezoelectric ceramics, different CuO amounts are doped to generate color centers for photochromism. The photoluminescence phenomenon exhibiting green emission under 375 nm excitation is observed in KNLNST piezoelectric ceramics, which is most commonly realized via rare‐earth doping in luminescent materials. KNLNST–0.3CuO ceramics with the highest oxygen vacancy concentration achieve a reversible luminescence modulation of 46.9% by altering light irradiation and thermal stimulus. Moreover, a hand‐rewritable optical information test demonstrates exceptional reproducibility and fatigue durability. This research displays the controllable photochromism and luminescence behaviors in ceramics via regulating oxygen vacancy concentration by CuO “hard” doping. The lead‐free high performance photoelectric ceramics fulfill the demands of potential applications in anti‐counterfeiting and optical storage devices.

Synthesis, Optical, Electrical, Fluorescence, Dielectric, Thermal, and Mechanical Characterization of 3-Aminopyridine (Scaffold in Drugs) Single Crystal

Objectives: To screen the optical, electrical, fluorescence, dielectric, thermal, and mechanical behavior of the 3-aminopyridine single crystal for its suitability in optoelectronic applications. Methods: A good single crystal of 3-aminopyridine (3-AP) was grown by the slow evaporation method. Findings: The lattice parameters of the grown crystal were determined using a single crystal X-ray diffractometer as, a = 6.184 (4) Å, b = 15.350 (6) Å, c = 5.361 (7) Å and the required functional groups C-N, NH2 bonds of 3-AP were recognized by the FTIR studies. The grown crystal was screened using the UV-Vis-NIR spectrum to understand the transmission and absorption character of the crystal. The various optical constants such as absorption coefficient, optical conductivity, and electrical conductivity of the crystal have been determined from the UV-Vis transmission plot. The lower cut-off wavelength of the 3-AP crystal was observed at 250 nm. The band gap of the grown crystal is found to be 4.5 eV. The emission property of the crystal was studied using fluorescence spectra. Violet, blue, and red emissions are observed from the fluorescence spectra. Thermal screening of the 3-AP crystal was performed using TGA and DTA. The 3-AP crystal remains stable up to 220 ºC and then the crystal begins to decompose up to 260 ºC due to the loss of the -NH2 group of the 3-aminopyridine. The Vickers hardness test revealed the nature of the material as soft type with Meyer’s index (n) of 2. The electronic polarization behavior of the crystal was examined using the dielectric study. Novelty: The lower cut-off wavelength of 250 nm, wide band gap of 4.5 eV, excellent transparency in the entire visible and near-infrared region, violet, blue, and red emission by the material are the distinguishing and mandatory features for optoelectronic applications. These features are good as compared to the 3-AP derivatives reported earlier. Keywords: Unit cell, Absorption, Emission, Conductivity, Strength, Loss

Optical and electrical degradation behavior of GaN-based UV-A laser diodes

The degradation mechanism of GaN-based ultraviolet (UV-A) laser diodes (LDs) is analyzed by studying the changes of their electrical and optical properties after aging process with the operation current below the threshold current (Ith). After aging treatment, Ith increases, the slope efficiency decreases, and the leakage current increases. In particular, the emission spectra of aged LD show significant broadening, with additional peaks on the shorter wavelength side. Both cathodoluminescence and deep level transient spectrum results indicate defects can develop around the active region of the LD, even when the operation current is below Ith. This leads to an increase in trap-assisted tunneling current and non-radiative recombination. The observed defects may result from the diffusion of water molecule in the environment from the cavity facet into the active region and formation of ON–CN and VGaON complex defects. These defects not only reduce the effective carrier concentration injected into the quantum well but also increase non-radiative recombination. These results will contribute to our understanding of the degradation mechanism of UV LDs and the preparation of long lifetime UV LDs.

Enhanced optical nonlinearity in suspensions of dual-resonance gold–copper chalcogenide core–shell nanoparticles

Plasmonic copper chalcogenide (Cu2−xE, E = S, Se, Te) nanoparticles (NPs) possess high potentials in photothermal therapy and photoacoustic tomography for their unique localized surface plasmon resonant absorption in the second near-infrared biologically transparent window. In this study, strong thermal-induced nonlinear negative-lens effect in aqueous suspensions containing Cu2−xSe NPs was observed. Furthermore, the nonlinear absorption was notably enhanced in aqueous suspensions containing Au@Cu2−xSe core–shell NPs, as the positive nonlinear absorption coefficient increased by 20-fold, attributed to the strong plasmonic coupling in Au@Cu2−xSe core–shell NPs. This finding underscores the importance of the nonlinear optical behaviors of plasmonic NPs in biomedical applications, as they offer extra strategy for optimizing systems and incorporating additional functionalities.

Exploring the Impact of 3D Printing Parameters on the THz Optical Characteristics of COC Material.

In terahertz (THz) optical systems, polymer-based manufacturing processes are employed to ensure product quality and the material performance necessary for proper system maintenance. Therefore, the precise manufacturing of system components, such as optical elements, is crucial for the optimal functioning of the systems. In this study, the authors investigated the impact of various 3D printing parameters using fused deposition modeling (FDM) on the optical properties of manufactured structures within the THz radiation range. The measurements were conducted on 3D printed samples using highly transparent and biocompatible cyclic olefin copolymer (COC), which may find applications in THz passive optics for "in vivo" measurements. The results of this study indicate that certain printing parameters significantly affect the optical behavior of the fabricated structures. The improperly configured printing parameters result in the worsening of THz optical properties. This is proved through a significant change in the refractive index value and undesirable increase in the absorption coefficient value. Furthermore, such misconfigurations may lead to the occurrence of defects within the printed structures. Finally, the recommended printing parameters, which improve the optical performance of the manufactured structures are presented.

Photochemical and electrochemical behavior of a molecular probe: Fluorescence on-off-on response to detect multiple ions (Cu2+, ClO− and CN−) with different rate of reaction

A molecular probe 3 containing phenyl substituted imidazolyl unit and diaminomaleonitrile (DAMN) moiety has been synthesized and characterized. Photophysical and electrochemical behavior probe 3 were studied in partial aqueous medium (ACN/H2O, 9.5:0.5 v/v). Probe 3 upon interaction with different class of ions showed sensitivity for Cu2+, ClO− and CN− ions with different response time and reaction rates due to variation in intramolecular charge transfer (ICT) process. Both Cu2+ and ClO− ions displayed enhanced emission due to hydrolysis of imine bond to form compound 2 in the medium whereas, with CN− fluorescence quenching was observed due to the deprotonation of –OH/–NH2 functions. The kinetic and optical behavior of the probe suggested that interaction occurred in two steps with Cu2+ (complexation and hydrolysis; absk1,2,3(Cu2+) = 1.17, 0.74 and 0.06 s−1) and ClO− (hydrolysis and deprotonation; absk1,2(ClO−) = 3.0 and 0.60 s−1) ions while CN− (absk1,2(CN−) = 2.13 and 1.66 s−1) induces deprotonation in one step. The interaction of probe 3 with ClO− was relatively fast than with Cu2+/CN− ions. Job's plot analysis between probe 3 and ions revealed a 1:1 (Cu2+/ClO−) and 1:2 (CN−) ratio stoichiometry with good limit of detection (nM) and binding affinity (LOD, 17; KCu2+ = 3.23 × 106 M−1; LOD, 18.5; KClO− = 5.23 × 105 M−1 and LOD, 23.2; KCN− = 5.50 × 109 M−2) respectively. Probe 3 displayed a naked–eye sensitive fluorescence response to detect tested ions on test paper strips and good recovery percentage of ions in real water sample analysis.

A comparative study on the optical performance of retro-reflective coatings before and after the aging process

Retro-reflective (RR) materials are largely included among the strategies to mitigate Urban Heat Island (UHI) phenomenon in the urban spaces thanks to their optical directional properties. As materials potentially used in the building exterior envelope, RR materials are subjected to outdoor aging and soiling processes, which could alter their optical behaviour. In this perspective, the investigation focuses on the characterization of the optical performance of several types of RR plaster coatings after outdoor aging and soiling processes. The RR plaster coatings were previously developed and studied, before undergoing the outdoor exposure. The RR samples were developed covering the support with a reflective white paint and glass beads. Five different microsphere diameter ranges and three different microsphere superficial density ranges have been employed. In this paper, the RR plaster coatings were tested in terms of optical properties after outdoor aging and soiling and results were compared with data of the same plaster coatings pre-aging. Generally, all RR aged samples show a lower solar reflectance in the Vis region with respect to the pre-aging conditions. The RR behaviour is qualitatively maintained after aging and soiling. The RR sample made of glass beads of 200–300 μm diameter range could represent the best solution both in pre- and post-conditions and both in terms of solar reflectance and retro-reflective behaviour, regardless of the density of microspheres used.