Blue Shift In Band Gap Research Articles

Revealing the Universal Pressure‐Driven Behavior of Hybrid Halide Perovskites and Unique Optical Modifiability in Extremely Soft 2D Tin‐Based System

AbstractAs promising photovoltaic materials, halide perovskites display large structural modifiability specific to their organic‐inorganic hybrid lattices, thus providing key to unlock many enhanced and novel physical properties. In particular, hybrid perovskites exhibit extraordinary functional responses to mechanical stimulation due to their soft lattices. However, a general pattern describing the evolution of perovskite properties under pressure is missing, rendering such research without theoretical guidance and further the optimization of optoelectronic performance. Here, a framework delineating the pressure‐dependent evolutions of lattice structure, bandgap, and photoluminescence (PL) across four distinct regions in all perovskites assuming 3D and 2D structures is unveiled, accrediting long‐range disorderness to be the common origin of bandgap blueshift, PL annihilation, and structural amorphization. Using such developed model as an instructional guideline, an optical bandgap and luminescent evolutions in quasi‐2D tin(II) iodide perovskites are revealed, where (C4H9NH3)2(CH3NH3)Sn2I7 (C4H9NH3+: butylammonium; CH3NH3+: methylammonium) is found to be the softest perovskite (bulk modulus ≈4.8 GPa) known so far. By meticulously choosing appropriate peak pressure ≈4 GPa, (C4H9NH3)2(CH3NH3)Sn2I7 shows irreversible defect healing (carrier lifetime prolongation from 7 to 22 ns) and permanent PL enhancement upon decompression to ambient condition, signifying practicality of the pressure‐driven behaviors unveiled in this work.

Colorimetric IPN hydrogels embedded with colloidal photonic crystals: A novel approach for the detection of ethanol and Ba2+ ions in water

A critical bottleneck in sensor technology is the rapid and precise detection of specific analytes in complex matrices, hindering advancements in environmental monitoring, healthcare, and industrial process control. This study addresses this challenge by introducing a novel composite hydrogel sensor designed for rapid and selective detection of ethanol and barium ions (Ba2+) in aqueous environments. The sensor integrates interpenetrating network (IPN) hydrogels with embedded colloidal photonic crystals (CPCs), synthesized via a solution-based polymerization approach. This innovative configuration allows CPCs to dynamically adjust their photonic bandgap in response to environmental changes, manifesting as a visible, colorimetric shift. This response stems from the synergy between the mechanical properties of the IPN hydrogel and the optical sensitivity of CPCs. Upon exposure to analytes such as ethanol and Ba2+, the sensor exhibits a rapid and reversible color transition that is directly proportional to their concentration. Notably, ethanol (0 vol%–80 vol%) and Ba2+ (5–17.5 mM) induce a distinct blueshift in the photonic bandgap and trigger a color change from red–orange to green due to the alteration in the swelling behavior of the IPN hydrogel, affecting its lattice constant. The IPN hydrogel–CPC composite demonstrates exceptional operational stability and facilitates rapid detection, making it ideal for on-site applications without the need for complex equipment. These characteristics make the composite hydrogel sensor a promising candidate for environmental monitoring, industrial process control, and public health diagnostics, paving the way for the development of next-generation responsive sensor materials.

Structural, Optical, Electrical and Photocatalytic Investigation of n-Type Zn2+-Doped α-Bi2O3 Nanoparticles for Optoelectronics Applications.

Herein, n-type pure and Zn2+-doped monoclinic bismuth oxide nanoparticles were synthesized by the citrate sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL) analysis, ultraviolet-visible (UV-vis) spectroscopy, and Hall effect measurements were used to study the effect of Zn2+ on the structural, optical, and electrical properties of nanoparticles. XRD revealed the monoclinic stable phase (α-Bi2O3) of all synthesized samples and the crystallite size of nanoparticles increased with increasing concentration of dopant. Optical analysis illustrated the red shift of absorption edge and blue shift of band gap with increasing concentration of dopant. Hall Effect measurements showed improved values (2.79 × 10-5 S cm-1 and 6.89 cm2/V·s) of conductivity and mobility, respectively, for Zn2+-doped α-Bi2O3 nanoparticles. The tuned optical band gap and improved electrical properties make Zn2+-doped α-Bi2O3 nanostructures promising candidates for optoelectronic devices. The degradation of methylene blue (MB, organic dye) in pure and zinc-doped α-Bi2O3 was investigated under solar irradiation. The optimum doping level of zinc (4.5% Zn2+-doped α-Bi2O3) reveals the attractive photocatalytic activity of α-Bi2O3 nanostructures due to electron trapping and detrapping for solar cells.

Structure evolution and energy band modulation in Ba-doped BiFeO3 thin films

Bi1−xBaxFeO3 (BBFO, x = 0, 0.03, 0.1) thin films were epitaxially grown on SrRuO3-buffered SrTiO3 (001) substrates by pulsed laser deposition. With increasing Ba content, the BBFO thin films show significantly reduced leakage currents but suppressed ferroelectric polarization. X-ray diffraction reciprocal space mappings and Raman spectra indicate a structural evolution from a rhombohedral-like to tetragonal-like phase in the BBFO thin films. Optical absorption and photoelectron spectroscopy measurements demonstrate a modulation of energy band structures in the BBFO thin films. With A-site Ba acceptor doping, the BBFO thin films exhibit a blue-shift of optical bandgap and an increase in work function. The energy positions of conduction and valence bands of the BBFO thin films have been modulated, and the Fermi level shifts down to the center of the forbidden band, but acceptor-doped BFO thin films still show n-type conduction. The presence of extra oxygen vacancies by acceptor doping is supposed to make contribution to conduction behavior. This study provides a method to manipulate the functional properties and gives insights into the physics of Ba doping in BFO thin films.

Defect-mediated time-efficient photocatalytic degradation of methylene blue and ciprofloxacin using tungsten-incorporated ternary perovskite BaSnO3 nanoparticles

Photocatalytic water purification has been extensively explored for its economic, eco-friendly, and sustainable aspects. In this study, tungsten (W) incorporated BaSn1-xWxO3 (x = 0 to 0.05) nanoparticles synthesized by facile hydrogen peroxide precipitation route has been demonstrated for photocatalytic degradation of methylene blue (MB) dye and ciprofloxacin (CIP) antibiotic. The structural analysis indicates the presence of hybrid composite-like nanostructures with reduced crystallinity. Optical studies reveal blueshift in bandgap and decrease in oxygen vacancy defects upon W-incorporation. Pure BaSnO3 shows overall enhanced photocatalytic activity towards MB (90.22%) and CIP (78.12%) after 240 min of white LED light and sunlight irradiation respectively. The 2 % W-incorporated BaSnO3 shows superior photocatalytic degradation of MB (26.89%) and CIP (45.14%) within first 30 min of irradiation confirming the presence of W to be beneficial in the process. The free radical study revealed the dominant role of reactive hole (h+) and oxygen radical (O2•−) species during photodegradation and their intermediates are investigated to elucidate the degradation mechanism of MB within 30 min of irradiation. This study is promising towards developing defect mediated and time-efficient photocatalysts for environmental remediation.

Revealing Unusual Bandgap Shifts with Temperature and Bandgap Renormalization Effect in Phase‐Stabilized Metal Halide Perovskite Thin Films

AbstractHybrid organic–inorganic metal halide perovskites are emerging materials in photovoltaics, whose bandgap is one of the most crucial parameters governing their light‐harvesting performance. This work presents the temperature and photocarrier density dependence of the bandgap in two phase‐stabilized perovskite thin films (MA0.3FA0.7PbI3 and MA0.3FA0.7Pb0.5Sn0.5I3) using photoluminescence and absorption spectroscopy. Contrasting bandgap shifts with temperature are observed between the two perovskites. Using X‐ray diffraction and in situ high‐pressure photoluminescence spectroscopy, it is shown that thermal expansion plays only a minor role in the large bandgap blueshift, which is attributed to the enhanced structural stability of the samples. The first‐principles calculations further demonstrate the significant impact of thermally induced lattice distortions on the bandgap widening. It is proposed that the anomalous trends are caused by the competition between static and dynamic distortions. Additionally, both the bandgap renormalization and band‐filling effects are directly observed for the first time in fluence‐dependent photoluminescence measurements and are employed to estimate the exciton effective mass. The results provide new insights into the basic understanding of thermal and charge‐accumulation effects on the band structure of hybrid perovskite thin films.

Characterization of Bi-doped ZnO nanorods prepared by chemical bath deposition method

This study investigates the effect of bismuth (Bi) doping on the structural, optical and electrical properties of ZnO nanorods prepared using a chemical bath deposition process. X-ray diffraction shows that the prepared nanorods are crystalline, and that Bi is successfully incorporated into the ZnO lattice. Scanning electron microscopy reveals an enhancement in the growth-rate upon Bi doping while X-ray photoelectron spectroscopy confirms the presence of Bi2O3 for Bi concentrations ≥ 2 at.%. Room temperature UV and deep-level emission peaks are observed in the as-grown ZnO nanorods. Following annealing at 573 K, in oxygen, only sharp UV luminescence peaks remain. Additinally, a blueshift in the optical band gap is observed following Bi doping. The current–voltage characteristics of the fabricated Schottky diodes show improved rectification behaviour after Bi doping. The best device is obtained at 3 at.% Bi with a Schottky barrier height and an ideality factor of 0.70 eV and 1.86, respectively.

Effect of yttrium doping on the crystal structure, optical, and photocatalytic properties of hydrothermally synthesized ZnO nanorods

The hydrothermal technique was utilized to fabricate yttrium doped ZnO nanorods (Y-doped ZnO). Various spectroscopic approaches were used to examine the effect of yttrium doping on the crystal structure, shape, energy bandgap, and photocatalytic performance of ZnO nanorods. The fact that Y-doped ZnO nanocatalysts had the same hexagonal wurtzite crystal structure and nanorod shape as like undoped ZnO, signifying that doped yttrium ions have no effect on the structural as well as morphological features of ZnO nanorods. By doping yttrium into the ZnO sites, the bandgap energy of the ZnO nanorods was significantly altered, and the photodegradation activity was improved. The absorption edge of the Y-doped ZnO nanorods was shifted towards the higher wavelengths and blue shift in bandgap was observed. It has been confirmed that yttrium doping increases the light sensitivity of ZnO in the visible region while providing several active charge transporters on the nanorods surface as well. The photocatalytic activity of Y-doped ZnO nanocatalysts was significantly increased by generated charge carriers. For doping concentrations of 1 %, 3 % and 5 %, the photodegradation activity of Y-doped ZnO nanorods is 71 %, 97 %, and 82 %, respectively, whereas the photodegradation efficiency of pure ZnO nanorods is 22 %. The photodegradation efficiency of ZnO:Y3 was found to be 4.4 times higher than the pristine ZnO nanorods. In addition to the photodegradation, the Y-doped ZnO nanorods are anticipated to offer a valued platform to the widespread applications in the field of photocatalysis like electrochemical water splitting, hydrogen production and supercapacitors.

Sputtering Al2O3 enhanced bandgap engineering for integrated photonic devices

We present experimental results of the application of Sputtering enhanced Quantum Well Intermixing (QWI) process, where the bandgap of InGaAsP/InP quantum well laser microstructure is effectively modified by intermixing quantum well and potential barrier layers through sputtering Al2O3-QWI. This technique creates point defects through plasma induced disordering in the process of sputtering Al2O3. The subsequent Rapid thermal Anneal (RTA) process is performed to increase the diffusion rate and quantum well intermixing. This results in an increased transitional energy and hence it modifies the bandgap essential for the development of next generation complex photonic integrated circuits (ICs). We report a large bandgap blue shift of 144 nm is achievable with a very high increase in photoluminescence (PL) intensity. The experimental results of the bandgap shifted waveguides and laser diodes are presented. Photoluminescence (PL) measurements of InGaAsP/InP laser structure were taken before and after Al2O3-QWI process. The proposed technique can provide reliable and fast post-growth wafer level fabrication of photonic devices monolithically.

Reduced Leakage Current and Enhanced Photovoltaic Effect in Zn-Doped BiFeO3 Thin Films

Zn-doped BiFeO3 (BFO) thin films with compositional formula BiFe1–xZnxO3 (x = 0, 0.1, and 0.2) have been epitaxially grown on SrRuO3 buffered SrTiO3 substrates by pulsed laser deposition. The high-concentration Zn doping does not suppress the ferroelectric polarization of the BFO films, and the Zn-doped BFO thin films also show reduced leakage current and an enhanced photovoltaic effect. By optical and photoelectron spectroscopy measurements, with Zn doping, the BFO thin films show more oxygen vacancies and a structural evolution, and moreover, a blue-shift of optical bandgap and an increase of work function are demonstrated. The reduction of leakage current and the enhancement of photovoltaic effect are related to the variation of interfacial Schottky junctions and oxygen vacancies with doping. This study reveals systematic insights into the effects of Zn doping on the physical properties of BFO thin films.

Structural and Electrical Studies on ZnS Quantum Dots Using PEG as Capping Agent

AbstractZinc sulfide (ZnS) nanoparticles are produced in this study utilizing a simple wet‐chemical precipitation procedure using polyethylene glycol (PEG) as a capping agent. To analyze the structural, morphological, electrical, and electronic properties of the material, the ZnS nano powder is studied using X‐ray diffraction (XRD), scanning electron microscopy (SEM), FTIR, UV–visible absorption spectroscopy, and impedance spectroscopy techniques. The XRD patterns confirm the formation of the cubic phase in as‐prepared ZnS samples, whereas SEM and AFM images show the formation of prismatic and spherical morphology of nano crystallites, confirming the XRD results. FTIR spectra confirm formation of ZnS stoichiometric compound with a partial shifting of vibration bands in the presence of PEG in precursor solution. Optical band gap spectra show a blue shift of band gap with decrease in particle size. The controlled growth kinetics in the presence of PEG the ZnS synthesized nanoparticles show a better quantum confinement effect and enhancement of electrical conductivity behavior as predicted from impedance measurements. For the temperature range of the current investigation, the temperature dependence of conductivity is found to obey the Davis‐Mott model.

Fabrication of Eco-friendly UV-visible Driven Ni:CaCO3 Photocatalyst for Sustainable Environmental Remediation

Nano CaCO3, polymethyl methacrylate (PMMA) decorated Ni-doped CaCO3 nanoparticles (CPN) were synthesized from natural calcium magnesium carbonate (CaMg(CO3)2) via biomimetic synthetic route. The obtained products were thoroughly characterized through various physico-chemical techniques such as UV-DRS, PL, FTIR, XRD, TG-DTA, FE-SEM with EDX mapping, HR-TEM and SAED patterns. The XRD results revealed that the prepared products were in pure rhombohedral structure with the size range of 20-50 nm, respectively. Compared to other synthesized products, the sample CPN6 exhibited a blue-shifted band gap (2.7 eV) and red-shifted absorption and emission values. The morphological analysis of the samples shows the aggregated and rhombohedral with high porous like structure. The TG-DTA analysis shows the good thermal stability (up to 830 ºC). The photocatalytic activity exhibits a higher degradation efficiency 87% and 97% against methylene blue and rhodamine B dyes, respectively. The effect of different scavenger agents (ascorbic acid, AgNO3, EDTA2NA and isopropanol acid) was used to examine the efficiency of the photocatalytic activity. Based on the results, the prepared CPN6 nanoparticles show a great potential candidate for removal of organic dyes in the aqueous medium.

Tailoring the Structural, Optical and Electrical Properties of Zinc Oxide Nanostructures by Zirconium Doping

Owing to its low resistivity, high transmittance, and tunable optical band gap, ZnO is of great interest for optoelectronic applications. Herein, the sol–gel technique was used to synthesize un-doped and zirconium-doped zinc oxide (ZZO) nanostructures with different concentrations of Zirconium (Zr). X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, and photoluminescence (PL) measurements were used to investigate the influence of Zr doping on the structural, optical, and electrical properties of developed nanostructures. XRD and SEM confirmed the increase in crystallite size with increasing concentrations of Zr. Raman analysis indicated the presence of oxygen vacancies in synthesized nanostructures. UV-Vis spectroscopy illustrated the blue shift of band gap and red shift of the absorption edge for ZZO nanostructures with increasing concentrations of Zr. For the measurement of electrical properties, the spin-coating technique was used to deposit un-doped and Zr-doped ZnO layers of ~165 nm thickness. The four-probe-point (4PP) method illustrated that the doping of Zr caused a reduction in electrical resistance. Hall Effect measurements showed a high value, 3.78 × 1020 cm−3, of the carrier concentration and a low value, 10.2 cm2/Vs, of the carrier mobility for the Zr-doped layer. The high optical transmittance of ~80%, wide band gap of 3.51 eV, low electrical resistivity of 1.35 × 10−3 Ω·cm, and maximum carrier concentration of 3.78 × 1020 cm−3 make ZZO nanostructures one of the most promising candidates for the application of transparent conductive oxide (TCO) in optoelectronic devices.

In-Situ Functionalization of Cotton Fabric by TiO2: The Influence of Application Routes

The desirable chemical, physical, electronic, and optical properties of TiO2, as well as its high availability, non-toxicity, and low price, make it very popular in the modern functional textile industry. Here, TiO2 from titanium tetraisopropoxide (TTIP) precursors at concentrations of 2, 4, and 6% and commercial TiO2 nanoparticles (NPs) in dispersion form were applied to cotton textiles using low-temperature application methods (i.e., sol–gel pad–dry–cure, pad–hydrothermal, and exhaustion–hydrothermal methods) to provide a systematic study of the influence of low-temperature application processes and TIIP concentration and on the overall properties of TiO2-functionalized textile materials. The treated cotton fabric samples were characterized using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction spectroscopy (XRD) to determine their surface morphology, chemical composition, and crystal structure, while the optical properties of the synthesized TiO2 were determined using the absorption method and Tauc plotting. Afterwards, corresponding UV protection properties and photocatalytic self-cleaning activity were evaluated. In contrast to commercial TiO2, a relatively thin TiO2 deposition with an amorphous structure and a blue-shifted band gap between 3.18 and 3.28 eV was formed when applied at low temperatures. A sol with a TIIP concentrations of 2 and 4% applied using the exhaustion–hydrothermal and sol–gel dry-cure method, respectively, proved to be optimal. Both applied sol concentrations provided good UV protection and excellent photocatalytic performance, which exceeded that of commercial TiO2, even though the Ti contents in the samples were two- to three-times lower and the synthesized TiO2 exhibited an amorphous structure.

Colorless SnO- and Sb2O3-containing borate and borosilicate glasses with small photoelastic and high refractive properties

We examined the relationship between optical properties and structures of 5s2-type cations such as Sn2+- and Sb3+-containing borate and borosilicate glass. Linear evolutions were observed for the compositional dependences of density, glass transition temperature, refractive index, and photoelastic constant in visible transparent oxide glasses. The structural information was provided using vibrational spectroscopy to elucidate polyhedral units of the borate and borosilicate systems. A weak ligand field around a Sn2+ close to tetrahedral borate unit, which is supported by applying density functional theory calculation, might lead to a blueshift of optical bandgap keeping small photoelastic constant and high refractive index.

Sputtered Ultrathin TiO2 as Electron Transport Layer in Silicon Heterojunction Solar Cell Technology.

This work presents the implementation of ultrathin TiO2 films, deposited at room temperature by radio-frequency magnetron sputtering, as electron-selective contacts in silicon heterojunction solar cells. The effect of the working pressure on the properties of the TiO2 layers and its subsequent impact on the main parameters of the device are studied. The material characterization revealed an amorphous structure regardless of the working pressure; a rougher surface; and a blue shift in bandgap in the TiO2 layer deposited at the highest-pressure value of 0.89 Pa. When incorporated as part of the passivated full-area electron contact in silicon heterojunction solar cell, the chemical passivation provided by the intrinsic a-Si:H rapidly deteriorates upon the sputtering of the ultra-thin TiO2 films, although a short anneal is shown to restore much of the passivation lost. The deposition pressure and film thicknesses proved to be critical for the efficiency of the devices. The film thicknesses below 2 nm are necessary to reach open-circuit values above 660 mV, regardless of the deposition pressure. More so, the fill-factor showed a strong dependence on deposition pressure, with the best values obtained for the highest deposition pressure, which we correlated to the porosity of the films. Overall, these results show the potential to fabricate silicon solar cells with a simple implementation of electron-selective TiO2 contact deposited by magnetron sputtering. These results show the potential to fabricate silicon solar cells with a simple implementation of electron-selective TiO2 contact.

Novel Thermal Decomposition Method for the Synthesis of Iron‐doped SnS2 Nanoparticles and Studies on their Peroxidase‐like Activity

AbstractIron‐doped SnS2 nanoparticles (Sn1‐xFexS2) have been synthesized by a novel thermal decomposition method. Phase analysis was done using powder XRD. FE‐SEM and TEM studies show flake‐like morphology for iron doped SnS2 nanoparticles. Diffuse reflectance spectroscopy results demonstrate blue shift of band gap of Sn1‐xFexS2 nanoparticles with respect to pure SnS2 nanoparticles. M−H measurements of iron doped SnS2 nanoparticles at 300 K and 2 K show weak ferromagnetic behaviour when x=0.10 and 0.15. When x=0.20, paramagnetic behaviour at 300 K and superparamagnetic behaviour at 2 K are observed. ZFC‐FC measurements were also carried out for the iron doped SnS2 nanoparticles. The Sn1‐xFexS2 nanoparticles were used as catalyst for peroxidase‐like activity and for the detection of H2O2.

Atomic insights into the influence of Bi doping on the optical properties of two-dimensional van der Waals layered InSe

As a narrow-gap semiconductor, III–VI two-dimensional (2D) van der Waals layered indium selenide (InSe) has attracted a lot of attention due to excellent physical properties. For potential optoelectronic applications, the tunability of the optical property is challenging, e.g., the modulation of optical bandgap commonly by element doping. However, the deep understanding of the influence of element doping on the microstructure and the optical properties lacks of systematic investigation. In this work, by using aberration-corrected high-angle annular dark-field scanning transmission electron microscopy, we investigate the influence of Bi doping on controlling of the microstructure and optical properties of InSe single crystal in detail. The results show that Bi doping can introduce additional stacking faults in InSe single crystal, and more importantly, the atomic spacing and lattice constant of Bi-doped InSe are changed a lot as compared to that of the undoped one. Further optical characterizations including photoluminescence and transmission spectra reveal that Bi-doping can broaden the transmission wavelength range of InSe and make its optical bandgap blue-shift, which can also be physically interpreted from the doping-induced structure change. Our work expands new ideas for the optical property modulation of 2D thin-layer materials and brings new possibilities for the development of thin-layer InSe optical devices.

Explanation of the Opposing Shifts in the Absorption Edge and the Optical Resonance in CuFeS2 Nanoparticles

Size-dependent change of the electronic band structure is one of the key features of nanoparticles in the quantum confinement region. CuFeS2 nanoparticles have a strong absorption feature in the visible region that has, controversially, been described as neither an excitonic transition nor a free carrier plasmon oscillation. Instead, the absorption feature in CuFeS2 nanoparticles has been attributed to quasi-static optical resonances from inter-band transitions between the valence band (VB), intermediate band (IB), and conduction band (CB). As such, we hypothesized that the feature should be subject to quantum confinement effects through modification of the electronic bands. In this paper, we show experimentally that the optical resonance absorption peak red-shifts and the optical band gap blue-shifts as the particle size decreases. Through density functional theory (DFT) and the tight binding (TB) modeling, we elucidate the size dependence of the band structure, especially focusing on the change in the IB. Using a Lorentzian oscillator optical model to simulate the absorption spectrum with inputs from the DFT-calculated band structure and band shifts from the TB model, we find that the size-dependent shifts of the optical resonance peak position in CuFeS2 are due to a tri-band quantum confinement effect that results in both the VB to IB and IB to CB gap expansion that accompanies a decrease in particle size. We also find that the transitions between the IB and CB play only a minor role in the optical spectrum. Moreover, the linear optical Lorentzian model predicts that the optical resonance peak is tunable across the visible range by partially filling the IB, lowering the CB, or expanding the IB.

Strain-size features of bare ZnSe:Cu and ZnSe:Cu@ZnS core/shell quantum dots from extensive X-ray diffraction analysis, and their photoluminescence properties

ZnSe:Cu d-dots and ZnSe:Cu@ZnS core/shell quantum dots (QDs) were synthesized under different synthesis regimes of Cu-dopant content, microwave irradiation time (MWIRT) and over-coating of ZnSe:Cu by ZnS shell in order to optimize their structural and photoluminescence (PL) properties. The morphological and microstructural characterizations broadly done by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), revealed the spherical shape, synthesis-condition tunable and almost uniform size distribution of bare and core/shell QDs. Extended X-ray diffraction analysis (XDA) was performed by employing both Williamson-Hall (W–H) and Williamson-Smallman (W–S) approaches in order to validate these methods and obtain lattice strain (ε), dislocation density (δ) and particle size. The results indicated that all the QDs had cubic zinc-blend structure with an average crystallite size of ∼1.5 nm, and shift of peak positions shift toward higher angles for core/shells compared with bare QDs. W–S and W–H's outputs for bare and core/shell QDs showed similar trends, i.e. the optimal Cu-content of 0.1 mol% with higher crystalline quality. In addition, bare and core/shell QDs were investigated by Ultraviolet–Visible and PL spectroscopy. The blue-shift of band gap for the synthesized ZnSe QDs (∼3.5 eV) in comparison with bulk counterpart (∼2.7 eV) confirmed the formation of nano-sized particles. It was found that these QDs exhibited PL emission in the range of 423–559 nm. After changing the experimental variables during the experiment, the samples with optimal PL were identified. In reasonable relation to the microstructural aspects, ZnSe:Cu(1.5%) under MWIRT = 6 min has the highest band-edge PL intensity, which was associated with increased particle size, reduced lattice strain and higher atomic order raised from MWIR. Among the core/shell QDs, ZnSe:Cu(1.5%)@ZnS under MWIR indicated the highest band-edge emission intensity, which besides the microstructural parameters, may be a result of the morphological change from spherical to nanorod as certified by TEM. In addition, ZnSe@ZnS under MWIR showed the highest trap-defect emission intensity. In brief, due to the strong experimental condition-dependence of studied features, which is very important in tuning the properties, the studied bare and core/shells can be promising agents in green-blue luminescent photometric-biological applications.