Doped System Research Articles

Metal atom doping with GeC: Tuning electronic, magnetic and electrocatalytic hydrogen evolution

The crystal structure stability, electronic and magnetic properties, field emission, and catalytic properties of the metal-doped GeC systems are investigated by the first principles. The Ef (formation energy) in the range of −5.713 to −14.240 eV indicates that the metal-doped GeC systems have energy stability. The Al-, Cr-, Fe-, Co-, Cu-, and Zn-doped GeC systems exhibit metallic properties, but the Ti-, V-, Mn-, and Ni-doped GeC systems retain semiconductor properties. Notably, the V-, Cr-, Mn-, Fe-, Co-, Cu-, and Zn-doped GeC systems exhibit magnetism due to doping effects. In addition, the Ti-, V-, Cr-, Mn-, Fe-, and Co-doped GeC systems have field emission properties relative to the intrinsic GeC due to the decrease of work function. Importantly, the low over-potential indicates that the doping systems have strong electro-catalytic hydrogen production ability. Therefore, the metal-doped GeC has potential applications in spintronic, field emission devices, and electro-catalytic hydrogen production.

The Influence of CdS on the Structural and Optical Properties of Nano ZnWO4

We investigated the influence of CdS on the structural and optical properties of nano ZnWO4 for optical applications. (1−x)ZnWO4/xCdS (x; 0 to 0.25) heterojunctions were formed and the structure and microstructure of the ZnWO4 and CdS phases developed were investigated using Rietveld refinement analysis for synchrotron X-ray diffraction data. Phase analysis revealed the phase percentage of the CdS phase is always less than the nominated value (x), implying merging of some Cd and S into ZnWO4. Raman spectra showed CdS peaks, confirming the existence of CdS. Scanning electron microscopy showed two distinct morphologies: plate-like particles (ZnWO4 phase) and spherical shape (CdS phase). UV–vis diffuse measurements revealed enhancement of absorbance and reduction in reflectance and transmittance, in the range 300–56 nm, as the amount of CdS (x) increased in the (1−x)ZnWO4/xCdS system. Band gap of the ZnWO4 phase reduced from 4.0 eV for x = 0.0 to 3.9, 3.6, and 2.9 eV for x = 0.05, 0.1, and 0.25, respectively. The highest refractive index values were obtained as the amount of CdS reached 0.05. Impact of alloying on linear and nonlinear parameters and emitted photoluminescence spectra was studied. Upon loading ZnWO4 with CdS, the PL intensity is greatly quenched and the whole spectrum is red shifted, from 480 to 540 nm. CIE chromaticity diagrams show that ZnWO4 sample without any doping exhibits a blue color while the doped system reveals green-yellow colors.

Atomistic modulating of structural, elastic, and optoelectronic behavior of pure TiO2 and Fe/TiO2 for photoelectrochemical water splitting application

Titanium dioxide (TiO2) has attracted much attention because of their desirable physicochemical properties especially in the water splitting process. In this work pure and Fe-doped TiO2 compounds are studies theoretically with the help of Generalized Gradient Approximation with the revised Pardew–Burke–Ernzerh (RPBE) exchange–correlation scheme. Total Density of States (TDOS) and Partial Density of States (DOS) were analyzed in detail which show that iron (Fe) and oxygen (O) orbitals hybridize, especially in the region of the doping system conduction band minima for both modes. Additionally, this interaction produces an energy level that effectively reduces the bandgap of the adsorbed system. Optical properties were elucidated which shows that Fe-doped TiO2 system results in high absorption and photoconductivity. Moreover, the results demonstrate low bandgap energy which is suitable for the reduction in water splitting without the need for external energy. Magnetic properties demonstrated that Fe-doped TiO2 systems show very low diamagnetic responses. The calculated elastic properties of Fe-doped TiO2 indicate ductile nature of the material with a strong average bond strength. Fe-doped TiO2 exhibited less microcracks with a mechanically stable composition.

Tunable electronic and magnetic properties of defective g-ZnO monolayer doping with non-metallic elements.

The electronic and magnetic properties of non-metallic (NM) elements doping defective graphene-like ZnO (g-ZnO) monolayer including O vacancy (VO) and Zn vacancy (VZn) are studied. The results show that VO-g-ZnO is a semiconductor and VZn-g-ZnO is a magnetic semiconductor. B, C, N, Si, P, 2S, and 2Si doping VO-g-ZnO systems present half-metal and magnetic semiconductors, and the magnetism mainly originates from the spin polarization of doping atoms. For single or double NM elements doping VZn-g-ZnO, 2P doping system presents a semiconductor, while other systems present ferromagnetic metal, half-metal, and magnetic semiconductor. The magnetism of single NM elements doping VZn-g-ZnO mainly comes from the spin polarization of O atoms near the defect point. For double NM elements doping VZn-g-ZnO, spin splitting occurs mainly in p orbitals of O atoms, dopant atoms, and d orbitals of Zn atoms. NM elements doping defect g-ZnO can effectively regulate the electronic and magnetic properties of the system. The software package VASP 5.4.1 (Vienna ab initio Simulation Package) is used for calculations in this paper. The local density approximation (LDA) is adopted as an exchange and correlation function to perform the structural optimization and analysis of electronic structure and magnetic properties.

Photoactivated Circularly Polarized Room‐Temperature Phosphorescence from Phenoselenazine Derivative and Its Application in Information Security†

Comprehensive SummaryRoom‐temperature phosphorescence (RTP) materials have experienced rapid development due to their potential in organic light‐ emitting diode, information security, bioimaging, etc. However, the design of chiral organic phosphors with circularly polarized RTP (CPP) property remains a formidable challenge. Here, we introduce a chiral perturbation approach using a combination of chiral binaphthol and phenoselenazine derivative to achieve CPP. The photoactivated CPP in polystyrene (PS) film demonstrates a luminescence dissymmetry factor (glum), emission efficiency, and RTP lifetime up to 9.32 × 10–3, 27.0%, and 40.0 ms, respectively. The remarkable sensitivity of PS film to oxygen and temperature enables the adjustable emission colors, ranging from green to offwhite and blue under varying conditions. The doping systems, utilizing hosts of triphenylphosphine and 9‐phenylcarbazole, demonstrate an extended CPP lifetime of 85.9 ms and exhibit a persistent mechanoluminescence property with low pressure response threshold as low as 0.15 N. The information security provided by this CPP material was attained via the using of diverse emission colors and afterglow generated by distinct UV irradiation times and host materials. Alternately, it can also be achieved by observing different emission patterns using R‐ and L‐polarizer. The research has presented a reliable approach for producing CPP materials with high emission efficiency and glum.

First principles computation of novel hydrogen-doped CsSrO3 with excellent optoelectronic properties as a potential photocatalyst for water splitting

This research exhaustively inquired about the structural, photocatalytic, mechanical, and optoelectronic characteristics of the cubic perovskite CsSrO3−x Hx with the CASTEP code’s implementation of the GGA-PBE formalism. It aims to examine the characteristics of CsSrO3−xHx cubic perovskite with varied concentrations of substituents (x = 0, 0.3, 0.6, 0.9, 1.2, 1.5, 1.8, 2.1, 2.4, 2.7, and 3.0). The stability and synthesizability of the compound are guaranteed by the values of elastic constants and negative formation enthalpies. As H-insertion increases, there are variations in the values of anisotropy and elastic moduli. A semiconductor’s wide bandgap narrows as dopant concentration rises, changing its nature from indirect to direct. The findings imply that the compound’s electronic characteristics can be altered through the application of dopants, rendering them appropriate for a range of optoelectronic uses. The inclusion of hydrogen caused the structural change from cubic to tetragonal and orthorhombic. The distortion caused the lattice parameters to vary in values. Tolerance factor lies in range of 0.7–1 that ensures structural stability of CsSrO3−x Hx. Our computed results reveal the anisotropic nature of our compound. The obtained bandgap for CsSrO3−xHx indicates that both O2 evolution and H2 reduction are allowed since the requisite redox potentials are satisfied. Photocatalytic properties of CsSrO2.4H0.6 reveals that it is the best doped system as a potential candidate for water-splitting photocatalysis, as it has equal effectiveness to both oxidation and reduction processes. The bandgap was shown to decrease from 5.33 eV to 2.812 eV at complete hydrogen insertion, which also had an impact on the material’s optoelectronic characteristics. All the optical considerations such as dielectric functions, refractive indices, extinction coefficients, optical reflectivity, absorption coefficients, and loss functions are also thoroughly explained. The material exhibits mechanical stability along with ionic and covalent bonding.

Continuous tuning of optical transition properties and phonon spectrum in Er3+ doped germano-tellurite glass system

With the development of science and the progress of technology, novel and advanced rare earth ions doped luminescent materials with higher performance are demanded in the both emerging and traditional applications. Understanding the rules for tuning the spectroscopic properties of these materials is crucial for their development. However, achieving precise control over the optical properties of rare earth doped materials using traditional design and synthesis methods, such as altering dopants and their concentrations or modifying the preparative conditions, still remains challenging. This work aims to adjust the optical transition characteristics of Er3+ doped germano-tellurite glasses by changing the glass components. First, the Er3+ doped germano-tellurite glass series were synthesized using a high-temperature melt-quenching method at optimized melting temperatures. The tuning of band gap energy and refractive index of the glasses were revealed, and it was found that both of them can be monotonically and continuously tuned by changing the glass composition. The optical transition intensity parameters of Er3+ in the glasses were calculated in the framework of traditional three-parameterized Judd-Ofelt theory using the absorption spectra, and furthermore the corresponding optical transition parameters including radiative transition rates and intrinsic lifetimes for some interested levels were alsoconfirmed. The results demonstrated that the optical transition parameters could be efficiently modulated by changing the glass composition, indicating that the spectral properties of Er3+ doped germano-tellurite glasses can be tuned for the practical applications. The reliability of the deduced tuning rule was validated by comparing the theoretical and experimental transition rate ratios of 2H11/2 → 4I15/2 to 4S3/2 → 4I15/2. Furthermore, the tuning regulation of the phonon spectra in relation to the glass composition was discovered, showing a concordance between theoretical predictions and experimental results. From the above facts, it can be concluded that the optical transition properties of Er3+ in germano-tellurite glasses can be substantially adjusted by modifying the glass composition. This work provides a new perspective for designing and developing novel luminescent materials to meet specific application needs.

Effects of Zn contents and doping positions on the mechanical properties of η′-Cu6Sn5

η′-Cu6Sn5 is one of the main components of intermetallic compounds in the solder joint of electronic components. The research on improving its performance will help to solve the problem of increasing mechanical properties, electrical conductivity and thermal conductivity of solder joints of electronic devices. In this paper, we use the first-principles method to calculate the effects of 0.57 at.% and 1.14 at.% Zn doped on the Cu1, Cu2, Cu3 and Cu4 positions of η′-Cu6Sn5 on the mechanical and electronic properties of the structure. And we draw a 3D model to express the mechanical anisotropy of the doping system. The calculated results show that doping Zn makes η′-Cu6Sn5 more stable. However, the addition of Zn also reduces the fracture toughness of η′-Cu6Sn5, increases the anisotropy of η′-Cu6Sn5, and weakens the shear resistance of the solder joint of electronic devices.

Investigating the Structural, Electronic and Magnetic Properties of Single Vanadium Atom Doped Germanene Monolayer using Density Functional Theory (DFT)

In this study, density functional theory (DFT) within generalized gradient approximation (GGA) as implemented in Quantum ESPRESSO package has been employed. The structural, electronic, and magnetic properties of single Vanadium atom (V)-doped germanene monolayer have been investigated. The doping is carried out in 2x2x1 supercell with 32 atoms which gives around 3.12% doping concentration. The results revealed that single V atom doped Germanene monolayer induced both ferromagnetic and antiferromagnetic behavior with total magnetic moment of about 0.77 μB and 1.95 μB respectively. Also the behavior of the pristine germanene remains unaffected by the single V doping. The stability of the doped system are investigated by calculating cohesive and binding energies. These results are in good agreement with many reported results in case of both graphene and silicene. It’s also suggested that, the single V-doped germanene monolayer can support the quantum anomalous Hall effect, which has significant potential for spintronic applications.Keyword: Density Functional Theory (DFT), Generalized Gradient Approximation (GGA), Structural, Electronic and Magnetic Properties, Doping, Germanene Monolayer

Functions of tensile and compressive strain on electronic and optical properties of B-doped monolayer arsenene.

The structurals stability, electronic structure, density of states (DOS), and optical properties of B-doped arsenene under biaxial tensile and compressive strains were investigated using density functional theory (DFT) calculations. The doping system was found to exhibit good stability. The introduction of B atom transformed the originally indirect band gap of arsenene into a direct band gap. Under compressive strain, the band gap remained direct, gradually decreasing in value. In contrast, under tensile strain, the direct band gap occurred a transition into an indirect band gap, of which value initially increasing and then decreasing with an increasing strain. The static dielectric constant was increased under both compressive and tensile strains, but compressive strain had a stronger effect. Compressive strain led to an increase in the imaginary peak of the dielectric function, while tensile strain resulted in a decrease. Moreover, as compressive strain increased, the absorption and loss function peak initially blue-shifted and then red-shifted, while tensile strain caused a gradual red-shift of the absorption peak. All DFT calculations were performed using Quantum Espresso software; the structures were optimized using generalized gradient approximation (GGA-PBE), and electronic structure and optical properties are performed using Heyd-Sceria-Ernzerhof (HSE06). The cut-off energy was set as 70 Ry, the Monkhorst-Pack grid was set to 10 × 10 × 1, the atomic convergence criterion was set as 1.0 × 10-6 Ry, and the convergence criterion of interatomic force was set as 1.0 × 10-4 Ry/Bohr.

Naphthyl substituted guest induce efficient room temperature phosphorescence by a triplet-triplet energy transfer mechanism

Room-temperature phosphorescent (RTP) materials have attracted more and more attention due to their long luminescence life and large Stokes displacement. Host-guest doping systems are highly regarded for their simplicity of preparation and the absence of complex synthesis processes. Strong RTP emission can be activated by the doping of a guest molecules, in particular by substituting the phenyl group in the host structure with a naphthalene group. In this study, derivatives of benzophenone were constructed as the host molecule, and used 2-Benzoylnaphthalene, a commercially available naphthyl-substituted analogue of benzophenone, as the guest molecule. The phosphorescent lifetime of the doped system can reach 335 ms and the phosphorescent quantum yield can reach 58 %, which is expected to be used in anti-counterfeiting encryption, biological imaging and other fields. This work provides a general and effective host-guest doping strategy for constructing various organic room temperature phosphorescent materials.

Tuning the potentials of aluminum phosphide nanotube photocatalyst for wastewater treatment through band gap engineering: a DFT study

The photocatalytic properties of semiconductor materials, which are controllable through the design of the bandgap structure, make them a promising catalyst for wastewater treatment. This work investigated the photocatalytic properties of single-walled aluminum phosphide nanotube (SWAlPNT) doped with different concentrations of boron (B) atoms for wastewater treatment. Analysis of the structural, electronic and optical properties of the SWAlPNT photocatalyst was performed using the density functional theory approach in terms of plane wave basis set and pseudopotential. SWAlPNT was found to be stable to B doping with 3.6% and 7.1% concentrations. The obtained formation energy values of 12.33 eV, 12.00 eV and 11.98 eV and also cohesive energies of −0.82, eV, −0.75 eV and 0.79 eV for pristine, 3.6% and 7.1% B-doped SWAlPNTs, revealed the systems’ well mechanical and thermodynamic stabilities. Results also revealed that cohesive energy decreases with an increase in concentration of B dopant, which significantly enhances efficient thermal stability. Electronic band gap calculations revealed that pristine SWAlPNT demonstrated a direct band gap value of 0.2 eV. Due to B doping, an indirect band gap value of 1.4 eV was obtained with 3.6% B-doped SWAlPNT, which agreed well with band gaps of other photocatalysts used for wastewater purification. Analysis using optical absorption spectra revealed that 3.6% B-doped system absorbs visible light while 7.1% doped system absorbs both visible and ultraviolet light. This study found both 3.6% and 7.1% B-doped SWAlPNT as suitable photocatalysts for wastewater treatment under solar irradiation, with the 3.6% B-doped system demonstrating relatively better performance for wastewater treatment.

Electronic and magnetic properties of Mn-doped and Mn-X (F, Cl, Br, I) co-doped modulated monolayer SnSe2

The density functional theory is employed for learning the modulation of the electronic structure and magnetic properties of monolayer SnSe2 by an Mn atom and by co-doping an Mn atom with a halogen atom. It is found that intrinsic SnSe2 is nonmagnetic, which is consistent with the properties of semiconductors. Following Mn atom doping, the doped system is magnetic and the magnetic moments are primarily responsible for the Mn atom. After co-doping the Mn atom with halogen atoms, the doped system's total magnetic moments are decreased. The examination of the electronic structure demonstrates that the doping of the Mn atom and the co-doping of the Mn atom with halogen atoms lead to the introduction of impurity energy levels into the doped system, which appear only in the spin-up part and do not cross the Fermi energy level. There is asymmetry between the spin-up and spin-down energy bands and the doped system exhibits magnetic semiconductor properties. The hybridization of the p-orbitals of the halogen atoms and the 3d orbitals of the Mn atom is primarily responsible for the introduction of impurity energy levels in the energy bands of the doped system. In the Mn-doped system, ionic bonds were shaped between Mn and Se. In the co-doped system, strong ionic bonds were shaped between the Mn atom and F, Cl atoms, and covalent bonds were shaped between the Mn atom and Br, I atoms.

Concentration effects on the local structures and electronic properties of Er x BaY2− x F8: a first-principles study

Er3+ doped barium yttrium fluoride (BaY2F8) crystal has gained long-term attention due to its great potential in laser and medical device applications. However, the local structures of Er3+ doped BaY2F8 system (Er:BYF) remain uncertain, and the effect of doping concentration on structures and properties is unknown. Therefore, in this study, the first-principles study of the structural evolution of Er x BaY2−x F8 (x = 0.125, 0.25) crystals was carried out. By means of density functional theory and particle swarm optimization algorithm, the stable structures of Er:BYF crystals with two different concentrations are shown as standard monoclinic structures with P2 symmetry for the first time. The impurity Er3+ ions successfully enter the main lattice, replacing the Y3+ ions, and forming a [ErF8]5− polyhedron with C 2 point group symmetry. By calculating the electronic properties, the band gap values of the two structures are significantly reduced compared with that of pure BaY2F8 crystal. However, the conduction band does not break through the Fermi level, and the crystals still maintain the insulation characteristic. According to the calculation of the electron local density function, we conclude that Er–F and Y–F in Er:BYF are connected by ionic bonds. These results fill a theoretical gap in the study of Er:BYF crystals and provide inspiration for structural evolution and material design at different doping concentrations.

Aerosol Doping System for Microscale Seamless p-n Patterning of Carbon Nanotube Films.

Carbon nanotube (CNT) films are extensively researched as a promising material for wearable thermoelectric generators (TEGs) owing to their good flexibility and high thermoelectric conversion ability. Miniaturizing a pair of p- and n-type thermocouples and increasing the number of repeating elements can effectively increase the power of TEGs. However, conventional p-n patterning methods, such as dipping and printing, have a coarse resolution at the submillimeter level, thereby limiting the miniaturization rate. This study developed an aerosol doping system as a fine n-doping method. A dopant aerosol with a <3 μm diameter was formed through ultrasonic nebulization and air separation, while n-doping was achieved by exposing the CNT film to the dopant aerosol. Microscale p-n patterning of 1 μm was achieved through exposure using small-sized aerosols at an exceptionally slow rate of 3 Å/min. This resolution is 100 times higher than those of conventional p-n patterning methods. The developed aerosol doping system for CNTs can also be used on organic semiconductor materials, such as PEDOT/PSS and perovskite materials. Therefore, it has the potential to significantly impact the realization of Internet of Things (IoT) terminals, such as flexible TEGs, transistors, and solar cells.

Adsorption of NO on ZnO monolayer doped with transition metal (Ti, V, Cr, Mn, Co, and Zr): The first-principles study

Nitric oxide (NO) is a harmful gas produced by fuel combustion in the petrochemical industry. In this paper, the gas sensitivity of NO molecule on ZnO monolayer (ZnO-ML) doped with transition metal (TM = Ti, V, Cr, Mn, Co, and Zr) is systematically investigated by the first-principles calculation. The results show that the adsorption mode of NO molecule on the doped system (TM-ZnO-ML) changes from physisorption to chemisorption, and adsorption energies range from −1.59 eV to −3.12 eV, which are 8–16 times the origin adsorption energy (−0.19 eV) on the pristine ZnO-ML. Meanwhile, the charge transfer between NO molecule and substrates increases by 4–13 times compared with the pristine ZnO-ML. Furthermore, under the applied electric field of −0.4 V/Å, the charges transferred from V-ZnO-ML to the NO increase to 0.54 e. All of the results reveal the broad application prospect of TM-ZnO-ML in NO gas sensors.

First-principles study on the coexistence of different valence states of Zn vacancy, Cu1+/2+ doping, and Hi in ZnO magnetic switch

In this study, we used first principles to investigate the magnetic sources and switches of Zn34Cu1+HiO36(VZn0), Zn34Cu1+HiO36(VZn2−), Zn34Cu2+HiO36(VZn0), and Zn34Cu2+HiO36(VZn2−) systems. On the basis of formation energy, phonon spectrum, and temporal variation of energy, we concluded that the above systems were all in a stable state. The doped system can be magnetized by adjusting the valence state of Zn vacancy, and the Zn34Cu1+HiO36(VZn0) and Zn34Cu2+HiO36(VZn2−) systems demonstrated magnetism. We found that the Zn34Cu1+HiO36(VZn0) system acquired magnetism through (O.↓↑+VZn")x⇔(↑O.+VZn"+↑O.)x⇔(↑O.+VZn"+↓O.)x super- and double-exchange interactions, whereas the magnetism of the Zn34Cu2+HiO36(VZn2−) system originated mainly from the action of the O1−–VZn2−–Cu2+-bound magnetic polaron and double exchange. Our theory provides a new approach for the use of magnetic switches in magnetic semiconductors.

Time-dependent and clustering-induced phosphorescence, mechanochromism, structural-function relationships, and advanced information encryption based on isomeric effects and host–guest doping

To explore the intrinsic mechanism of pure organic room temperature and clustering-induced phosphorescence and investigate mechanochromism and structural-function relationships, here, 4-(2-(9H-carbazol-9-yl)phenyl)-2-amino-6-methoxypyridine-3,5-dicarbonitrile (Lo-CzAD), 4-(3-(9H-carbazol-9-yl)phenyl)-2-amino-6-methoxypyridine-3,5-dicarbonitrile (Lm-CzAD), and 4-(4-(9H-carbazol-9-yl)phenyl)-2-amino-6-methoxypyridine-3,5-dicarbonitrile (Lp-CzAD) were designed and synthesized by choosing self-made carbazole and 3, 5-dicyanopyridine (DCP) unit as electron acceptor and electron donor in sequence. Compared with crystals Lm-CzAD and Lp-CzAD, crystal Lo-CzAD shows better room temperature phosphorescence (RTP) performance, with RTP lifetimes of 187.16 ms, as well as afterglows 1s, which are attributed to twisted carbazole unit and donor–acceptor (D-A) molecular conformation, big crystal density and spin orbit coupling constant ξ (S1 → T1 and S1 → T2), as well as intermolecular H type stacking and small ξ (S0 → T1). By choosing urea and PPh3 as host materials and tuning doping ratio, four doping systems were successfully constructed, significantly improving RTP performance of Lo-CzAD and Lp-CzAD, as well as showing different fluorescence and RTP. The lifetimes and afterglows of pure organic Urea/Lo-CzAD and Urea/Lp-CzAD systems are up to 478.42 ms, 5 s, 261.66 ms and 4.5 s in turn. Moreover, Lo-CzAD and Lp-CzAD show time-dependent RTP in doping systems due to monomer and aggregate dispersion, as well as clustering-induced phosphorescence. Based on the different luminescent properties, multiple information encryptions were successfully constructed.

Effect of doped heteroatom on monolayer SnSe2 adsorption of Na

Based on the first principles, we have calculated the influence of B, Br, and N atom doping on the adsorption properties and optoelectronic properties of monolayer SnSe2 adsorbed Na. The calculations show that vacancy is the most favorable adsorption site for the Na atom. Among the three doping systems, the B-doped system has the best adsorption energy and height and Na’s adsorption capacity. After the adsorption of the Na atom by intrinsic SnSe2, the system behaves from a semiconductor to a metal nature. Doping Br atom increases the adsorption system’s Fermi energy level, the conduction band’s overall energy increases and the electrical conductivity is enhanced. Doping B and N atoms change the adsorption system from metallic to p-type semiconductor properties. The system’s adsorption performance, electrical conductivity, and energy band tunability are improved. Due to the electrostatic repulsion between Na atoms, the adsorption energy of the system shows an increasing trend with the increase in the number of adsorbed Na atoms on the surface. The maximum specific capacity of the surface of the doped system is 373 mAhg−1, and the system has high storage capacity. Optical property calculations show that the static refractive index of the Br-doped adsorption system is maximum. The static refractive index of the doped adsorption system is minimal. Doping makes the system’s energy loss smaller, complex conductivity decreases, intermolecular interactions decrease, and the adsorption system becomes more stable.

Ultra-long room temperature phosphorescence, intrinsic mechanisms and application based on host-guest doping systems

To construct efficient room-temperature phosphorescence (RTP) doping systems by simple doping methods, isomers 2-(2-(9H-carbazol-9-yl)benzyl)malononitrile (o-CzCN), 2-(3-(9H-carbazol-9-yl)benzyl)malononitrile (m-CzCN) and 2-(4-(9H-carbazol-9-yl)benzyl)malononitrile (p-CzCN) were designed and synthesized by choosing commercial carbazole. Based on the structure-function relationships of three isomers and excellent compatibility between carbazole and benzocarbazole, 2-(3-(9H-carbazol-9-yl)benzyl)malononitrile (Lm-CzCN) and 2-(3-(5H-benzo[b]carbazol-5-yl)benzyl)malononitrile (m-BCzCN) were prepared by self-made carbazole and 2-naphthylamine. Then, Lm-CzCN/m-BCzCN was constructed and optimized by dissolution and rapid evaporation, as well as tuning the mass ratios between Lm-CzCN and m-BCzCN. Lm-CzCN shows excitation dependent RTP and afterglow lifetimes, as well as concentration dependent RTP emission in poly(vinyl alcohol) (PVA) films, while 1% m-BCzCN@PVA film emits bright green afterglow, with RTP and afterglow lifetimes of 2.303 and 17 s in turn, as well as RTP quantum yield of 0.22. More importantly, Lm-CzCN/m-BCzCN presents ultra-long room temperature phosphorescence, with RTP and afterglow lifetimes of 597.58 ms and 8 s, respectively. Moreover, crystals m-CzCN and p-CzCN, as well as Lm-CzCN/m-BCzCN can be excited by visible light of 440 nm, showing yellow afterglow of 1–4 s. Noteworthy, polymorphism o-CzCNY and o-CzCNB were found, whose different emission was investigated by molecular conformation, intermolecular arrangement and stacking patterns. Finally, multiple encryptions were successfully constructed based on the different luminescent properties.