Photoluminescence Decay Research Articles

Multi‐Responsive 0D Organic–Inorganic Hybrid Cuprous Bromides Constructed via Ultra‐Facile Approaches for Multimodal Luminescent Anti‐Counterfeiting

AbstractLuminescent anti‐counterfeiting has the advantages of high secrecy, low cost, flexible design, simple operation, and convenient light‐regulation of luminescent materials, which makes it easy to achieve high‐level multimodal anti‐counterfeiting. Here, zero‐dimensional (0D) organic–inorganic hybrid luminescent crystals (TPA)CuBr2 (TPA+ = [N(CH2CH2CH3)4]+) with multiple responses to ultraviolet (UV) light, water, and thermal stimulus are synthesized through an ultra‐facile approach for multimodal luminescent anti‐counterfeiting. Water‐sensitive (TPA)CuBr2 could transform into 0D (TPA)2Cu4Br6 upon external water stimulus, accompanied by the change of luminescence color from cyan to orange under UV light irradiation. Both (TPA)CuBr2 and (TPA)2Cu4Br6 exhibit high photoluminescence quantum yields, and long photoluminescence decay lifetimes. In addition, (TPA)CuBr2 and (TPA)2Cu4Br6 show reversible “on‐off” luminescence phenomena and excellent cycling stability under thermal stimulus. Exhilaratingly, multimodal anti‐counterfeiting luminescent labels with high‐security level could be fabricated based on the multiple responsive organic–inorganic hybrid cuprous bromides. Moreover, the test paper based on (TPA)CuBr2 could be fabricated for the detection of trace water in isopropanol. This work demonstrates the capabilities of (TPA)CuBr2 and (TPA)2Cu4Br6 as high‐security anti‐counterfeiting materials and luminescent sensors, which provides an important reference for exploring 0D metal halides for high‐level luminescent anti‐counterfeiting.

The Mn-Doped CsPbCl3 Perovskite Nanocrystals as a Photoluminescent Probe for Copper Ions Detection

Trace detection of toxic heavy metal ions is a hot topic in the sensing research area, especially in the organic phase using inorganic fluorescent colloidal nanocrystals. We report Mn-doped CsPbCl3 perovskite nanocrystals (PNCs), which were synthesized via the hot-injection method, as a fluorescent probe for the detection of copper ions in hexane. The introduction of Mn altered the emission peak, and lower the toxicity of the probe material. The photoluminescence (PL) intensity of Mn-doped CsPbCl3 PNCs is significantly quenched after contact with the [Formula: see text] solution. The mechanism of Cu quenching is electron transfer, which is experimentally proved by analyzing the PL spectrum, absorption spectrum and PL decay lifetime. The sensor in solution shape and solid shape is both prepared and their detection range from 10 nM to 500 [Formula: see text]M. The limit of detection in a low concentration area reaches 10 nM, showing great potential in sensing applications. This work expands the wavelength area of the [Formula: see text] detection probe by perovskite nanocrystals, and also improves the properties of probe material in optical performance, low toxicity, and stability.

High Operating Temperature Mid-Infrared InGaAs/GaAs Submonolayer Quantum Dot Quantum Cascade Detectors on Silicon

Monolithic integration of infrared photodetectors on a silicon platform is a promising solution for the development of scalable and affordable photodetectors and infrared focal plane arrays. We report on integration of submonolayer quantum dot quantum cascade detectors (SML QD QCDs) on Si substrates via direct growth. Threading dislocation density has been reduced to the level of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 10^{7}$ </tex-math></inline-formula> cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-2}$ </tex-math></inline-formula> with the high-quality GaAs-on-Si virtual substrate. We also conducted a morphology analysis for the SML QD QCDs through a transmission electron microscope strain contrast image and to the best of our knowledge, high quality InGaAs/GaAs SML QDs were clearly observed on silicon for the first time. Photoluminescence decay time of the as-grown SML QD QCDs on Si was measured to be around 300 ps, which is comparable to the reference QCDs on lattice-matched GaAs substrates. With the high-quality III-V epitaxial layers and SML QDs, the quantum cascade detectors on Si achieved a normal incident photoresponse temperature up to 160 K under zero bias.

Luminescence properties and energy transfer studies in thermally stable Bi2O3: Sm3+, Eu3+ phosphor

The advent of innovative rare-earth based metal oxide phosphors has prompted increasing interest in the search for highly efficient red emitting phosphors for various optoelectronic devices, lighting and display applications and motivated the research community to develop some promising, state-of-the-art, and potential red phosphors to meet the necessary requirements. In this study, a series of Sm3+ (1–7 mol%) doped, Sm3+ (5%) doped and Eu3+ (2–5 mol%) co-doped Bi2O3 red phosphors were synthesized by a facile urea assisted auto-combustion process. The X-ray diffraction (XRD) analysis of the phosphors ascertains the tetragonal crystal structure without any trace of impurity. The UV-Vis-NIR absorption study of the phosphors was carried out in 200–1000 nm range and the estimated optical band gap of the phosphors was lying in the range of 2.778–2.831 eV. The photoluminescence (PL) emission studies were performed at an excitation wavelength of 481 nm in the 550–720 nm range. The effective energy transfer mechanism from Sm3+ to Eu3+ in the Bi2O3 phosphor has been ascribed to the dipole-dipole (d-d) interaction. The energy transfer process was further validated by PL decay time measurements. The CIE color coordinates were obtained using PL emission data. The CIE chromaticity diagram ascertains that the emission color of Bi2O3: Sm3+ phosphors were tuned from reddish-orange to the red region by varying the concentration of Eu3+ ions. The temperature dependent PL study of the phosphors was taken out in the range of 293–453 K and was found thermally stable at elevated temperatures.

Efficient Ultrafast Scintillation of KLuS2:Pr3+ Phosphor: A Candidate for Fast-Timing Applications

A set of ${\mathrm{Pr}}^{3+}$-doped ${\mathrm{KLuS}}_{2}$ samples with different $\mathrm{Pr}$ concentrations are synthesized in the form of transparent crystalline hexagonal platelets by chemical reaction under a flow of hydrogen sulfide. Their structural, optical, and scintillation properties are investigated thoroughly by means of x-ray powder diffraction, time-resolved luminescence spectroscopy, scintillation light yield, and decay measurements to assess the spectroscopic properties of ${\mathrm{Pr}}^{3+}$ ions in the ${\mathrm{KLuS}}_{2}$ host. Charge-trapping processes are further investigated by electron paramagnetic resonance. The fundamental absorption band edge of the ${\mathrm{KLuS}}_{2}$ host is located at 303 nm, the absorption due to the ${\mathrm{Pr}}^{3+}$ 4f \ensuremath{\rightarrow} 5d transition is found at 347 nm, the emission maximum is given by the $4{f}^{1}5d1$ \ensuremath{\rightarrow} ${}^{3}{H}_{4}$ transition of the ${\mathrm{Pr}}^{3+}$ ion at 380 nm, and the leading photoluminescence and scintillation decay time is around 1 ns at room temperature. The moderate scintillation light yield reaches 7200 ph/MeV. A phenomenological model is fitted to the measured temperature dependences of the photoluminescence emission spectra and photoluminescence decay times to better understand the dynamics of the 5d excited state of the ${\mathrm{Pr}}^{3+}$ center in the ${\mathrm{KLuS}}_{2}$ host. The number of photons emitted in the first nanosecond of the scintillation response is evaluated and found to be considerably higher (1.6--2.5 times) than that in the commercial $(\mathrm{Lu};\mathrm{Y}{)}_{2}({\mathrm{SiO}}_{4})\mathrm{O}$:$\mathrm{Ce},\mathrm{Ca}$ scintillator, which shows the potential of $\mathrm{Pr}$-doped ${\mathrm{KLuS}}_{2}$ for fast-timing scintillator applications.

Water‐Stable and Photo‐Patternable Siloxane‐Encapsulated Upconversion Nanoparticles toward Flexible Near‐Infrared Phototransistors

AbstractUpconversion nanoparticles (UCNPs), as near‐infrared (NIR) absorbers, are promising materials for use in flexible NIR photodetectors, which can be applied for wearable healthcare applications due to their advantages in a broad spectral range, high photostability, and biocompatibility. However, to apply UCNPs in wearable and large‐area integrated devices, water stability and micro‐patterning methods are required. In this work, the UCNPs are encapsulated with a siloxane polymer (UCNP@SiOx) via a sol–gel process to enable photo‐patternability and photo‐stabililty in water conditions. The UCNP@SiOx can be photo‐patterned down to micron‐scale feature sizes and exhibit no significant decrease in upconversion photoluminescence (PL) intensities and PL decay time after immersion in water for 2 h. Moreover, UCNP@SiOx is evaluated by an in vitro biocompatibility test and found to be non‐toxic. By integrating the UCNP@SiOx with MoS2 phototransistors (MoS2 + UCNP@SiOx), the devices exhibit enhanced responsivity (0.79 A W−1) and specific detectivity (2.22 × 107 Jones), which are 2.8 times higher than in the bare MoS2 phototransistors, and excellent mechanical durability over 1000 cycles of 20% compression and re‐stretch test. This work opens the way for the facile synthesis of water‐stable and photo‐patternable siloxane‐encapsulated UCNPs and a strategy for fabricating high‐performance flexible NIR phototransistors through wavelength conversion.

Down-conversion and up-conversion photoluminescence studies of Er3+ doped calcium zinc borosilicate glass for optical fiber amplifiers

A series of Er3+ ion doped calcium zinc borosilicate (CZBS) glass with composition 15ZnO-(10-x)CaO-10SiO2-65B2O3-xEr2O3 (x = 0.1, 0.5, 1.0, 1.5, 2.0 mol%) has been synthesized using conventional melt quenching technique. The non-crystalline nature of the as-synthesized glass is established through X-Ray diffraction (XRD). Fourier Transform Infrared (FT-IR) spectral studies present a full picture of the functional groups present in the glass system. The absorption, up-conversion (UC) and down-conversion (DC) photoluminescence (PL) and corresponding PL decay dynamics, and laser power dependent PL are investigated to better understand the optical properties and energy transfer mechanism in the glass matrices. The radiative properties such as transition probability (AR), branching ratios (βR), radiative lifetimes (τR) and near infrared (NIR) emission quantum efficiency (η) are estimated. The absorption, emission cross-sections and optical gain coefficients reveal the potential applications as laser amplifiers. The results favorably suggest the potential utility of these Er3+ doped CZBS glasses in solid-state lighting and optical communication devices.

Controlled growth and spectroscopy characterization of blue violet perovskite quantum dots in borate glasses

Blue violet light emitting CsPb(Cl/Br)3 perovskite quantum dots glasses (QDGs) have been successfully fabricated in multi-component borate glass matrix by melt quenching and heat treatment. The spectral characteristics have been evaluated by photoluminescence (PL), PL excitation (PLE), PL decay and absorption spectra. The recipe and preparation conditions have been optimized for controlled growth of QDs. By using raw materials of NH4Br/NH4Cl/PbO and crucible cover, optimizing composition of Na2O/K2O in matrix, melting temperature and time, heat treatment temperature and time, and NH4Cl and NH4Br contents, we have finally realized blue violet exciton emission in target range of 405–440 nm. The PL wavelength adjustment is comprehensive effect of the abovementioned influence factors. The emission in short wavelength of 405–440 nm is due to controlled growth of the QDs. In final CsPb(Cl/Br)3 QDs, the contents of Cl and Br are suitable and the Cl/Br ratios are large. A little Br is necessary for growth of CsPb(Cl/Br)3 QDs and then the Br is partially replaced by Cl at suitable treatment condition. Unsymmetrical PL spectrum profile of some samples is explained as reabsorption effect by monitoring PL spectral profile and PL decay. The temperature characteristics of PL spectra show good recoverability after a temperature cycle.

Fabrication of Transparent Green-Emitting Plastic Scintillators by the Modified Polymerization Method

The green-emitting plastic scintillators with high transparence, short decay time and high quantum yield were fabricated by the modified thermal polymerization procedure. The effects of different concentrations of primary and secondary fluorescent dopants on photoluminescence performance, such as fluorescence intensity, decay time and absolute quantum yield, were investigated through orthogonal experiments. The optimal formula ratio for the plastic scintillator was that the primary dopant concentration was 0.25 wt.% and the secondary dopant concentration was 0.03 wt.%. The photoluminescence decay time of the optimal sample was 3.37 ns, which was faster than that of EJ-260 (6.57 ns) and its corresponding quantum yield was 91.57%, compared to that of EJ-260 (98.59%).

Extended dimensionality of the density of states in InGaAs coupled quantum dot-ring structures as evidenced by radiative decay times

We observed radiative decay times as a function of temperature by analyzing the thermal relaxation from the excited exciton states in InGaAs coupled quantum dot (QD)–quantum ring (QR) structures. To investigate the confinement of electron-hole pair wavefunctions in the coupled QD-QR structures, we measured radiative decay times with temperature, where the photoluminescence decay time of electron-hole pairs was corrected based on the relative photoluminescence intensity at 4 K to discriminate the radiative processes. For decoupled QRs and QDs, quasi-one dimensional (for QRs) and zero-dimensional (for QDs) densities of states have been reported. However, dimensional densities of states from decoupled QRs and QDs do not apply when the distance between QRs and QDs is sufficiently close in the coupled QD-QR structure owing to coupling interactions (both short- and long-range). In the present coupled structure, QD and QR is connected at the bottom, and the top side peak-to-peak distance is approximately 24 nm. Based on our observations, the power order of temperature dependence increased from 0 to 0.33 (for QDs) and from 0.7 to 1.32 (for QRs), corresponding to the quasi-zero-dimensional (∼Tα=0.33) and quasi-two-dimensional (∼Tα=1.32) confinement state, respectively, owing to amended wavefunctions of electron-hole pairs and dark states effect.

Detection of Single Charge Trapping Defects in Semiconductor Particles by Evaluating Photon Antibunching in Delayed Photoluminescence.

Time-resolved analysis of photon cross-correlation function g(2)(τ) is applied to photoluminescence (PL) of individual submicrometer size MAPbI3 perovskite crystals. Surprisingly, an antibunching effect in the long-living tail of PL is observed, while the prompt PL obeys the photon statistics typical for a classical emitter. We propose that antibunched photons from the PL decay tail originate from radiative recombination of detrapped charge carriers which were initially captured by a very limited number (down to one) of shallow defect states. The concentration of these trapping sites is estimated to be in the range 1013-1016 cm-3. In principle, photon correlations can be also caused by highly nonlinear Auger recombination processes; however, in our case it requires unrealistically large Auger recombination coefficients. The potential of the time-resolved g(2)(0) for unambiguous identification of charge rerecombination processes in semiconductors considering the actual number of charge carries and defects states per particle is demonstrated.

Enhanced spectroscopic traits of Eu3+/Dy3+ co-doped doro-telluro-borate glasses: Effect of silver nanoparticles embedment

Herein, Eu3+/Dy3+ co-doped doro-telluro-borate glasses containing silver nanoparticles have been made using the melt-quenching method. The spectroscopic properties of as-produced glasses were analyzed, experimentally and theoretically. Ag NPs was obtained with a median size of 25.50 nm and LSPR absorption peak at 479 nm. From the Photoluminescence (PL) and Fluorescence decay profiles, it was shown that the efficient energy transfer from Ag NPs to Dy3+ (Eu3+) ions alongside the local field effect induced by Ag NPs leads to the significant augmentation in the inclusive spectroscopic qualities wherein the glass composition of EDAx with x = 0.8 disclosed better branching ratio (64.73%), stimulated emission cross-section (50.76 ×10−21cm2), color correlated temperature (4123 K) and quantum efficiency (80.38%). Besides, Ag NPs integration into the glass network promoted white light emission by the excited Dy3+ (Eu3+) ions with varying tints. The unique results obtained in this study provides useful information for designing white light emitting diode (W-LEDs) devices.

Gd-doped silica fiber fabricated using surface plasmachemical deposition with view to radiation sensor applications

A Gd3+-doped-silica optical fiber free of other codopants in the core was fabricated with the help of surface plasma chemical vapor deposition (SPCVD) for the first time. The SPCVD-process parameters are described as well as the fiber properties in the as-drawn state (absorption and photoluminescence (PL) spectra upon excimer-laser excitation at λ = 276 and 193 nm and PL decay kinetics) and during γ-irradiation at 1–3.5 Gy/s up to 0.5–1.4 kGy (radiation-induced absorption (RIA) and radioluminescence (RL)). The 315-nm RL band is argued to be suitable for real time dose-rate monitoring, although RIA and persistent luminescence can influence the RL intensity. The possibility to suppress RIA on completion of irradiation by thermal annealing at 500 °C during 15 min was demonstrated.

Luminescent and Scintillation Characteristics of Ce-doped (Y2-xGdx)Si2O7 single crystal

Yttrium-gadolinium pyrosilicate ((Y2-xGdx)Si2O7) single crystals with different ratios of yttrium to gadolinium (x = 0.1–1.9) and 2% Ce-dopant were successfully synthesized using the floating-zone method. In this work, photoluminescence (PL) and scintillation properties of 2% Ce-doped (Y2-xGdx)Si2O7 were investigated. The conducted experiments included PL decay time and emission, X-ray-induced decay time and scintillation spectra, an afterglow analysis, as well as the total scintillation light yield by γ-ray-irradiation pulse-height spectra. Interesting results were including the considerably low afterglow at 20 ms of 40–65 ppm compared to commercial scintillator materials on the market like CdWO4. Further, the high light yield of 21,800 ph/MeV was achieved in Y0.5Gd1.5Si2O7 under 662 keV (137Cs) γ-ray-irradiation.

Effect of B2O3 on luminescence and scintillation properties of Ce3+-doped gadolinium aluminium–silicate glass

Different B2O3 content was added to Ce3+–doped Gd2O3–Al2O3–SiO2 (xBGAS:1.1Ce3+, x = 0, 5, 10, 15) glasses to improve the photoluminescence (PL) and scintillation properties. The transmittance of 15BGAS:1.1Ce3+ glass is over 80%. The X–ray absorption near edge spectroscopy (XANES) spectra imply that Ce4+ can be effectively reduced to Ce3+ in the glasses by adding Si3N4. The excitation and emission spectra show a blue shift with increase of B2O3 content. The photoluminescence quantum yield (PL QY) increases with the increase of B2O3 content, reached the maximum of 59.55% when x = 15. The PL decay time of the glasses exhibits typical values (44–50 ns) due to 5d→4f transition of Ce3+ ions. The PL thermal activation energy become larger, indicating that xBGAS:1.1Ce3+ glasses have better luminescent thermal stability. The integral X–ray excited luminescence (XEL) intensity of the 15BGAS:1.1Ce3+ glass is 37.38% of Bi4Ge3O12 (BGO) crystal, and the light yield is 1267 ph/MeV with an energy resolution of 23.22% at 662 keV when exposed to γ–rays. With the increase of B2O3 content, the fast component of scintillation decay time gradually becomes shorter and the slow component becomes longer. The thermally stimulated luminescence (TSL) curves were measured to investigate the trap depth and density of defects in xBGAS:1.1Ce3+ glasses.

Improved Crystallization of Lead Halide Perovskite in Two-Step Growth Method by Polymer-Assisted "Slow-Release Effect".

Fast reaction between organic salt and lead iodide always leads to small perovskite crystallites and concentrated defects. Here, polyacrylic acid is blended with organic salt, so as to regulate the crystallization in a two-step growth method. It is observed that addition of polyacrylic acid retards aggregation and crystallization behavior of the organic salt, and slows down the reaction rate between organic salt and PbI2 , by which "slow-release effect" is defined. Such effect improves crystallization of perovskite. X-ray diffraction study shows that, after addition of 2mm polyacrylic acid, average crystallite size of perovskite increases from ≈40 to ≈90nm, meanwhile, grain size increases. Thermal admittance spectroscopy study shows that trap density is reduced by nearly one order (especially for deep energy levels). Due to the improved crystallization and reduced trap density, charge recombination is obviously reduced, while lifetime of charge carriers in perovskite film and devices are prolonged, according to time-resolved photoluminescence and transient photo-voltage decay curve tests, respectively. Accordingly, power conversion efficiency of the device is promoted from 19.96 (±0.41)% to 21.84 (±0.25)% (with a champion efficiency of 22.31%), and further elevated to 24.19% after surface modification by octylammonium iodide.

Insight into Hot Carrier Kinetics of CsPbBr3/ZnO Heterostructures for Photodetector Application

Understanding the hot carrier kinetics in heterostructures of inorganic halide perovskite nanocrystals (PNCs) and extraction of the excess energy of hot-carriers is crucial for their future emergence in optoelectronic devices. Herein, CsPbBr3/ZnO heterostructures have been prepared via the most adopted in situ hot-injection method, and ZnO nanoparticles were obtained by a simple chemical process. We have investigated the carrier transfer dynamics through steady-state and ultrafast optical measurements. Steady-state measurements (i.e., photoluminescence and time-resolved photoluminescence decay) reveal that electron transfer from PNCs to surface-attached ZnO nanoparticles is the most probable transition process that happened in heterostructured systems. Furthermore, deep insights into the charge transfer kinetics were investigated by performing ultrafast transient absorption (UTA) spectroscopy at two varying pump fluences (i.e., 0.40 and 0.20 mW) with an excitation wavelength of 450 nm. UTA analysis reveals a significant slow hot carrier cooling at 0.40 mW fluence (from 670 fs to 1.56 ps) and 0.20 mW (from 480 fs to 1.23 ps) in CsPbBr3/ZnO heterostructure systems, suggesting reduced exciton recombination and high charge-carrier transfer through the heterostructure interface. The efficient charge extraction in CsPbBr3/ZnO results in a measurable change in photodetector responsivity and detectivity. This study provides an understanding of the hot carrier kinetics of metal halide perovskites CsPbBr3/ZnO for optoelectronic device applications.

Thermally stable Sm3+ -doped alkali zinc alumino borosilicate (AZABS) glass for warm white light generation and w-LED applications.

Samarium ion (Sm3+ )-doped alkali zinc alumino borosilicate (AZABS) glass was synthesized via quick melt quench technique. Various spectroscopic studies like optical absorption, photoluminescence (PL) emission, PL excitation, temperature-dependent PL and PL decay kinetics were performed on the as prepared glass system. Under 402 nm excitation, three sharp bands at wavelengths 563, 599 and 645 nm corresponding to transitions 4 G5/2 → 6 H5/2 , 6 H7/2 and 6 H9/2 , respectively, can be seen in the PL emission spectra. The 0.25 mol% Sm3+ glass has the highest intensity for these emissions. The lanthanide interaction in the glass matrix is dipole-dipole in nature as was proven from Dexter's analysis. The direct bandgap of 0.25 mol% Sm3+ -doped AZABS glass was calculated to be 2.88 eV. The lifetimes of the as prepared glass range from 1.93 ms for the lowest concentration of Sm3+ to 0.75 ms for the highest. From temperature dependent PL studies, the activation energy for 0.25 mol% Sm3+ -doped AZABS glass was found to be 0.19 eV which shows high thermal stability of this glass. We propose to utilize these Sm3+ -doped AZABS glasses for white-light emitting diodes (w-LEDs) and solid-state lighting (SSL) applications.

A one-dimensional organic-inorganic hybrid copper(I)-halide with broadband emission

Organic-inorganic perovskite materials have shown excellent performance and strong competitiveness in high-performance photovoltaic and optoelectronic devices. Besides the color-tunable and narrow-band emissions realized in hybrid perovskites, broadband emission from lead-halide perovskites has also attracted strong interest for applications in the next generation of solid-state lighting. Although great progress has been made in lead halide perovskites, a very important aspect that hinders their commercial exploitation is the severe lead toxicity. In this research, a lead-free copper(I)-iodine hybrid was synthesized by a solution evaporation method at room temperature. Single crystal X-ray diffraction shows that this hybrid possesses the chemical formula of C6H5CH2CH2NH3CuI2. The C6H5CH2CH2NH3CuI2 belongs to the monoclinic phase with the C2/c space group, where the edge-sharing [CuI4] tetrahedral chains are separated by organic C6H5CH2CH2NH3+ ions, exhibiting one-dimensional (1D) crystal structure. The optical band-gap of C6H5CH2CH2NH3CuI2 was determined to be 4.02 eV. The photoluminescence (PL) spectrum shows a broadband emission ranging from 380 nm to 780 nm and peaks at 542 nm together with a small peak at 336 nm, which can be attributed to the emission of self-trapped exciton (STE) and free exciton (FE), respectively. The large Stokes shift of 230 nm between the PL and photoluminescence excitation (PLE) as well as the broad emission was ascribed to the Jahn–Teller lattice distortion of [CuI4] tetrahedra. The reduced 1D characteristic facilitates the tetrahedral distortion. PL decay analysis shows that the average lifetime of STE is about 66.9 ns? Temperature and time-dependent PL measurements show that the normal working temperature of this luminescent material should be no higher than 100 °C. Theoretical calculations were performed to better understand this compound. The successful synthesis and preliminary optical investigations on C6H5CH2CH2NH3CuI2 can be of great significance for offering more environmental-benign options in both solid-state lighting and other perovskite optoelectronic devices.

Influence of Eu3+ dopant on lithium barium gadolinium phosphate glass properties for orange-reddish photonic devices

The Eu3+-doped lithium barium gadolinium phosphate glasses were prepared using the conventional melt-quenching method with different concentrations of Eu2O3 and Gd2O3. The physical characteristics were determined by refractive index, density, molar volume, oxygen packing volume, and oxidation states. Moreover, the optical characteristics were investigated via photoluminescence spectroscopy (PL), UV-vis spectroscopy, Radioluminescence (RL), and decay time. It was found that the Gd2O3 concentration of 12 mol% was the optimum composition for further investigations of the Eu2O3 doping concentration optimization. The emission spectra of PL and RL showed the strongest intensity of orange-reddish emission (λEx = 394 nm) when the Eu2O3 concentration was at 0.3 mol% corresponding to energy transition from 5D0→7F0,1,2,3,4. The oxidation state of Eu3+ ions due to the formation of non-bridging oxygens (NBO) in the glass network was confirmed by using X-ray Absorption Near Edge Spectroscopy (XANE). Furthermore, the high transparency and fast decay time in the range of 2.4–2.8 ms displayed the potential to improve laser and radiation detector performances.