High-performance Nonlinear Optical Materials Research Articles

Syntheses and nonlinear optical behavior of four-arm star-shaped phthalocyanine indium polymers containing azobenzene

In this report, a series of novel four-arm star-shaped polymethyl methacrylate with core of phthalocyanine indium polymers (InPc-(PMMAx)4) were achieved with different molecular weights through Activator ReGenerated by Electron Transfer Atom Transfer Radical Polymerization, using the synthesized phthalocyanine indium (InPc-Br) as initiator. The InPc-(PMMAx)4 polymers were characterized by NMR, FT-IR, GPC, UV–Vis and PL spectroscopy. The nonlinear optical (NLO) properties of InPc-(PMMAx)4 polymers were investigated by the Z-scan technique and it revealed that InPc-(PMMA16)4 obtained satisfactory NLO properties with imaginary third order susceptibility (Im[χ(3)]) of 16.4 × 10−12 esu. Furthermore, reacting polymer InPc-(PMMA16)4 with NaN3 and 1-(4-nitrophenyl)-2-(4-(prop-2-yn-1-yloxy) phenyl) diazene (Azo-yne) through click reaction, a novel InPc polymer InPc-(PMMA16-b-Azo)4 was successfully synthesized. InPc-(PMMA16-b-Azo)4 displayed a weak fluorescence at 707 nm compared to InPc-(PMMA16)4, demonstrating the energy transfer (ET) process between Azo and InPc, which could be proved by density functional theory. Because of the ET process, InPc-(PMMA16-b-Azo)4 exhibited a better NLO performance than InPc-(PMMA16)4, with Im[χ(3)] of 20.7 × 10−12 esu. In addition, the InPc-(PMMA16-b-Azo)4/PMMA complexes were prepared for the convenience of practical application, and it exhibited an excellent Im[χ(3)] value of 30.2 × 10−12 esu and a satisfactory limiting threshold of 0.04 J/cm2. The significantly enhanced NLO properties of InPc-(PMMA16-b-Azo)4/PMMA complexes demonstrate a weaker aggregation effect in polymethyl methacrylate matrix than in methyl methacrylate solution. Our study provides a promising design strategy to synthesize high performance NLO materials for practical applications.

Switching of second-order nonlinear response effected by different acceptors: The impacts of environment and frequency dispersion

In this work, the second-order nonlinear optical (NLO) switch features and electron transition properties for a series of donor-acceptor Stenhouse adducts (DASAs) were explored. The systems we studied contain of a given diethylamine donor and different acceptors, which can be photoinduced from open form to closed form. The calculation results show a remarkable difference in the first hyperpolarizability (β) value between two configurations for each of studied systems, revealing a conspicuous NLO switch feature. Interestingly, in the conditions of gas phase, solid phase polarization effects or frequency dispersion effects, the introduction of indandione acceptor demonstrates the most significant NLO switch feature due to the largest βopen/βclose ratio of compound 5. In general, the differences in the degree of π-electron conjugation and electron transition property between two configurations are responsible for the contrast of NLO response. Our work reveals the features of NLO switch on structure and electron transition property, which will provide some guidance for designing high performance NLO materials.

Influence of bi-alkali metals doping over Al12N12 nanocage on stability and optoelectronic properties: A DFT investigation

Bi-alkali metal atoms (Li2, Na2, K2) doped Al12N12 nanocages with remarkable stability are achieved for the first-time using density functional theory. Bi-alkali doping is a highly efficient technique to bring high stability as compared to single alkali metal atom doping. It is revealed that bi-alkali metal atoms doping significantly reduced the wide HOMO-LUMO energy gap (3.93 eV) of pure Al12N12 nanocage to 0.74–1.67 eV. The reduction in HOMO-LUMO energy gap is due to the formation of new HOMO energy levels having diffused excess electrons which is further confirmed by the PDOS and TDOS plots. The bi-alkali metal atoms doped Al12N12 nanocages exhibit remarkable nonlinear optical response. The highest first hyperpolarizability of 1.2 × 105 au is observed for K2@Ntop. Clearly, the doping of high atomic number atoms brings larger hyperpolarizabilities, while the non-monotonic trend is observed for M2@b66 series where Na2@b66 has a large hyperpolarizability value. These fascinating results will be helpful for achieving the potential applications of inorganic Al12N12 nanocages in the optoelectronic devices and high performance nonlinear optical materials.

Exploring Li4N and Li4O superalkalis as efficient dopants for the Al12N12 nanocage to design high performance nonlinear optical materials with high thermodynamic stability

The influence of superalkalis (Li4N and Li4O) doping on the structural, electrical, optical and nonlinear optical properties of the Al12N12 nanocage has been theoretically investigated through density functional theory. The research findings show the strong impact of the superalkalis over the Al12N12 nanocage. The doping of superalkalis significantly reduced the HOMO-LUMO energy gap up to 50.75% compared to the pristine Al12N12 nanocage due to the formation of a new HOMO energy levels. All isomers possess diffuse excess electrons and are electrides in nature. The results also revealed the higher stability (interaction energies of up to −118.49 kcal/mol) and deep ultraviolet transparency of the studied isomers. Furthermore, superalkali doping dramatically enhanced the nonlinear optical response of the Al12N12 nanocage. The largest first hyperpolarizability of 5.7 × 104 au is achieved for isomer A of the Li4N@Al12N12 series. This outstanding increase in the NLO response is attributed to the small transition energies (1.27–2.73 eV) and charge transfer from the superalkali towards the nanocage. AIM and NCI analysis were also performed to investigate the nature of intermolecular interactions between the superalkali and Al12N12 nanocage. AIM topological analysis revealed that a closed shell electrostatic interaction is dominant. These findings offer an insight into designing and fabricating nonlinear optical materials with exceptional features for their widespread applications in optoelectronics.

Second-order nonlinear optical property of carbon–boron–nitride heterostructure: Vertical carbon-segment into the BN nanosheet

Due to wide applications in optoelectronic field, carbon-boron-nitride materials have attracted considerable interest from scientists. In the present work, the structures and first hyperpolarizility (βtot) of three closed shell isoelectronic structures BNC-n (n = 1–3) were investigated, in which BNC-n are designed by the increasing vertical carbon-segment doping into the BN nanosheet. Results show the βtot value of isoelectronic are increased with the increase of the doping carbon-segment. Among these isoelectronic structures, the βtot value (2.80 × 104 au) of BNC-3 is larger (19 times) than the 1.51 × 103 au of BNC-1. Correspondingly, the BNC-3 has the smallest transition energy (1.455 eV), which is obviously smaller than 3.884 eV of BNC-1. We hope the present work is beneficial for scientists to understand and design high performance nonlinear optical materials on carbon-boron-nitride hetero-materials.

Theoretical investigation of superalkali clusters M2OCN and M2NCO (where M=Li, Na, K) as excess electron system with significant static and dynamic nonlinear optical response

Confining excess electrons in a specific space is an effective strategy to design high-performance nonlinear optical (NLO) materials. Herein, with the aid of density functional theory (DFT) calculations, we investigated the nonlinear optical (NLO) properties of excess electron superalkali/supermetals M2OCN and M2NCO (where M = Li, Na, K) clusters. The electronic and optoelectronic properties of these superalkali clusters are studied at CAM-B3LYP/6−311+G(d,p) level of theory. The studied clusters possess significant thermal stability and their binding energies per atom are in the range of -120.98 to -128.04 kcal mol−1. Furthermore, the analyzed superalkali clusters show excellent electronic properties. Being excess electron candidate, these supermetals clusters show significant reduced HOMO-LUMO gaps (-4.40 ∼ 2.79 eV). The HOMO-LUMO gaps are further reduced for M2NCO configuration that reveals excellent conductive properties. The further comprehensive piture of electronic properties is obtained from the plotted density of states (DOS) analysis spectra. With the justified excess electron character, the static hyperpolarizability (βo) response increases up to 1.4 × 104 au. The strong resemblance of total hyperplarizability with βvec provides evidence for practical design of NLO materials. Moreover, the hyperpolarizability from the two-level βtl model nicely correlates with βo. Besides, static nonlinearity, frequency-dependent hyperpolarizability (β(ω)) shows remarkable values for electro-optical pockel’s effect β(-ω;ω,0) at dispersion frequency of 532 nm whereas, the second harmonic generation (SGH) phenomena is much pronounced at higher frequency (ω = 1064 nm). The obtained second hyperpolarizability (γ(ω)) response increase up to 2.1 × 108 au. The dc-Kerr effect (nonlinear refractive index) γ(-ω;ω,0,0) shows a remarkable response (2.1 × 1010 au) at ω = 532 nm.

Pb18 O8 Cl15 I5 : A Polar Lead Mixed Oxyhalide with Unprecedented Architecture and Excellent Infrared Nonlinear Optical Properties.

To develop high-performance nonlinear optical (NLO) materials for infrared (IR) applications, we have applied a rational element-composition design strategy and investigated the unexplored PbO-PbCl2 -PbI2 system. By doing so, we discovered a new polar lead mixed oxyhalide, Pb18 O8 Cl15 I5 , the first synthetic metal oxyhalide combining both Cl- and I- . Pb18 O8 Cl15 I5 reveals an unprecedented structural feature with two different dimensional types of oxocentered Pb-O units, namely, [O4 Pb8 ]8+ clusters and [OPb2 ]2+ chains. Centimeter-sized single crystals of Pb18 O8 Cl15 I5 have been successfully grown under ambient conditions. Remarkably, Pb18 O8 Cl15 I5 satisfies all fundamental yet rigorous criteria for high-performance IR NLO materials, exhibiting the widest IR transparency (up to 16.0 μm) among oxide-based crystals, strong second-harmonic generation response (1.05×AgGaS2 ), superior birefringence (0.086 at 636 nm), and a high laser-induced damage threshold (8.5×AgGaS2 ).

Structural, photophysical and nonlinear optical limiting properties of sandwich phthalocyanines with different rare earth metals

Four sandwich phthalocyanines with different rare earth metals (La, Y, Yb and Sc) are synthesized to investigate the influence of aggregation on nonlinear optical limiting effect. Hyperchem fitting results show that the distance between the phthalocyanine rings of the four phthalocyanine compounds is 2.81, 2.69, 2.56 and 2.38 Å for LaPc (Tetra-β-(4-nitro) lanthanum phthalocyanine), YPc (Tetra-β-(4-nitro) yttrium phthalocyanine), YbPc (Tetra-β-(4-nitro) ytterbium phthalocyanine) and ScPc (Tetra-β-(4-nitro) scandium phthalocyanine), respectively. As the radius of rare earth ions decreases, the interlayer spacing between phthalocyanine rings decreases, which greatly increases the degree of aggregation between phthalocyanine rings. As a result, the photophysical and nonlinear absorption coefficients of different rare-earth phthalocyanines also show regular changes. The nonlinear absorption coefficients of the four rare-earth phthalocyanines were LaPc (β = 1.86ⅹ10−10 m/W), YPc (β = 9.78ⅹ10−11 m/W), YbPc (β = 6.63ⅹ10−11 m/W), ScPc (β = 7.43ⅹ10−11 m/W), respectively, indicating that the degree of aggregation between phthalocyanine rings gradually increases as the radius of rare earth metals changes from La, Y, Yb, to Sc, which inhibits the reverse saturable absorption process of the triplet states, resulting in a gradual decrease of the nonlinear absorption coefficient. The experimental results fully reveal the effect of the aggregation effect between phthalocyanine rings on photophysical and nonlinear optical properties, and would provide a theoretical basis for the design of high-performance nonlinear optical materials.

First row transition metals decorated boron phosphide nanoclusters as nonlinear optical materials with high thermodynamic stability and enhanced electronic properties; A detailed quantum chemical study

Electronic as well as nonlinear optical properties (first hyperpolarizabilities) of boron phosphide nanoclusters doped with first row transition metals (Sc–Zn) are explored using density functional theory (DFT) calculations. Four different doping sites (b64, b66, r4, and r6) of the B12P12 nanocluster are considered for doping of the transition metals. Computational results revealed that these transition metals doped boron phosphide complexes are highly stable, and their HOMO–LUMO energy gaps are considerably reduced as compared to the pristine B12P12 nanocage. The highest interaction energy (−74.42 kcal mol−1) is observed for Ni@r4-B12P12 complex. The lowest HOMO–LUMO energy gap (1.44 eV) is computed for Sc@b64-B12P12 complex. Moreover, adsorption of the first row transition metals (Sc–Zn) on the surface of B12P12 nanocluster significantly enhanced the nonlinear optical response of the resultant complexes. The highest static first hyperpolarizability value (4.4 × 104 au) is computed for Sc@r4-B12P12 complex. Moreover, frequency dependent hyperpolarizability calculations are also performed to evaluate the practicality of the transition metal doped boron phosphide (M@B12P12) complexes. The highest electro-optical Pockels effect (EOPE) value of 4.4 × 105 au is computed for Sc@r4-B12P12 complex while Sc@r6-B12P12 gives the highest second harmonic generation (SHG) value of 1.1 × 105 au. This study will be advantageous for providing guidance in further designing of new high-performance nonlinear optical (NLO) materials.

Syntheses and characterizations of Zn (Ⅱ) Phthalocyanines & Naphthopyrans based polymers for improved nonlinear optical properties

In this paper, four organic polymers of poly [(MMA)x-co-(NPMA)y-co-(CPMA)z] and four zinc phthalocyanine (ZnPc) polymers of poly [(MMA)x-co-(NPMA)y-co-(ZnPc)z] have been successfully synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, where MMA is methyl methacrylate, NPMA is 3,3-diphenyl-8-methacryloxy-3H-naphtho [2,1-b]pyran, and CPMA is 3,4-dicyanophenyl methacrylate. The components of these polymers have been fully characterized by 1H and 13C NMR, FT-IR, Raman, XPS, UV–Vis, and photoluminescence (PL) spectroscopy. From PL spectra, poly [(MMA)x-co-(NPMA)y-co-(ZnPc)z] polymers display strong fluorescence quenching by the energy transfer (ET) process between NPMA and ZnPc moieties. The third-order nonlinear optical (NLO) properties of poly [(MMA)x-co-(NPMA)y-co-(ZnPc)z] polymers have been investigated by the Z-scan technique, and poly [(MMA)168-co-(NPMA)5.2-co-(ZnPc)1.2] (Q4) showed the best NLO properties owing to the much stronger ET between NP and ZnPc units. Furthermore, it is essential to obtain doped poly (methyl methacrylate) (PMMA) films for practical application. The poly [(MMA)168-co-(NPMA)5.2-co-(ZnPc)1.2]/PMMA film exhibited a higher nonlinear absorption coefficient of 61 × 10−11 m/W and a lower limiting threshold of 0.19 J/cm2. The significantly enhanced NLO properties of poly [(MMA)168-co-(NPMA)5.2-co-(ZnPc)1.2]/PMMA film compared with solution are attributed to the weaker aggregation effect in PMMA film. This research provides a promising molecular design strategy for high performance NLO materials.

Heteroborospherene nanoclusters as high-performance nonlinear optical materials

Today, the design of new compounds with giant nonlinear optical responses is attracted to many researchers. Inspired by an interesting finding of a new class of heteroborospherenes which were formed by doping four carbon atoms in the B364- nanocluster (C4B32), we suggest the alkali metal-doped C4B32 (M@C4B32, M=Li, Na, and K) nanoclusters as high-performance nonlinear optical materials. Our results show that the alkali metal atoms have a considerable effect on the structural and electronic properties of the C4B32 nanocluster. We found that the doping alkali metal can remarkably decrease the HOMO-LUMO gap and significantly increases the first hyperpolarizability of the C4B32 nanocluster. Also, our results reveal that the first hyperpolarizability of the M@C4B32 nanoclusters can be progressively enhanced by increasing the atomic number of alkali metals. The effect of external electric fields on the nonlinear optical responses of the M@C4B32 has been systematically explored. We found that the first hyperpolarizability of the M@C4B32 compounds can be gradually increased by increasing the imposed external electric field from zero to the critical external electric field along the charge transfer direction (M→C4B32). Accordingly, this work presents an efficient strategy to improve the nonlinear optical responses of the heteroborospherenes.

Theoretical study on novel superalkali doped graphdiyne complexes: Unique approach for the enhancement of electronic and nonlinear optical response

Based on DFT calculations, we have explored the changes in geometric, electronic and nonlinear optical (NLO) properties of M3O and M3S (M = Li, Na and K) doped graphdiyne. The doping of superalkalis not only changes the electronic properties of GDY but also remarkably alters the NLO properties. Stabilities of doped GDY are evaluated through interaction energies. HOMO-LUMO gap, NBO, polarizability and first hyperpolarizability (βo) calculations at hybrid (B3LYP) and long-range corrected methods (CAM-B3LYP, LC-BLYP and ωB97XD) are performed for studying the NLO properties of doped GDY complexes. Significantly high values of βo are observed for all doped structures, especially for Na3S@GDY (1.36×105 au). Reduction in HOMO-LUMO gap concomitant with increase of βo value is attributed to the strong interaction of Na3S with GDY. The partial density of states (PDOS) spectra strongly support the existence of excess electrons. To rationalize the trends in first hyperpolarizability of doped GDY, two level model calculations are also performed. This study of super alkalis doped GDY will be advantageous for promoting the potential applications of the nanostructures in designing new types of electronic nanodevices and production of high performance nonlinear optical materials.

Insight into the Expanded Mislinked Porphyrins with High Second Order Nonlinear Optical Response.

Materials with outstanding nonlinear optical (NLO) response exhibit excellent prospects in electrooptic devices. Thus, it is essential to find a high-performance NLO material to meet the growing demand for high-speed data transmission. In this study, theoretical investigations on the second order NLO properties of the novel expanded mislinked thia-norhexaphyrin, sulfur-free pentaphyrin, and their substituted derivatives were performed using density functional theory. Theoretical calculations display that the approximate planar structures of sulfur-free pentaphyrin embedded with two five-membered rings exhibits a remarkable NLO response and holds large dipolar contribution (ΦJ=1 = 63.5%) to the first hyperpolarizability among four parent expanded mislinked porphyrins. The static first hyperpolarizability values of these expanded porphyrins were found to range from 3490 to 14 229 au. In addition, the second order NLO response of these porphyrins has greatly improved except for minority electron-releasing- and electron-withdrawing-group substituted cases, and the static first hyperpolarizability value has increased to 47 950 au after installing the donor and acceptor groups. Unambiguous evidence reveals that expanded mislinked porphyrin can serve as a potential candidate for NLO materials.

Theoretical study of electronic and nonlinear optical properties of Janus all-cis-1,2,3,4,5,6-hexafluorocyclohexane derivative with an extended π conjugation

More and more scientists are paying attention to Janus all-cis-1,2,3,4,5,6-hexafluorocyclohexane (hereafter system 1) due to interesting structure and unique property. The question of how to design high-performance nonlinear optical (NLO) materials based on system 1 is studied. In this work, by means of ab initio calculations, a new series of system 1 derivatives with an extended π conjugation have been theoretically designed by introducing –(CH=CH)n–NO2 or –(CH=CH)n–NH2 (n = 1–4, 8, 12) chain into system 1. The results indicate that introducing –(CH=CH)n–NO2 or –(CH=CH)n–NH2 chain leads to small transition energy, which can bring a significant enhancement of the first hyperpolarizability. It is expected that these novel systems exhibit the large first hyperpolarizabilities up to 4.17 × 104 au. Moreover, the effect of different substitutions on the NLO responses is investigated. With increasing the first hyperpolarizability, the –(CH=CH)n–NH2 chain has an advantage over the –(CH=CH)n–NO2 chain. It is hoped that this work can provide theoretical help for the design of new nonlinear optical materials.

Giant and Multistage Nonlinear Optical Response in Porphyrin-Based Surface-Supported Metal-Organic Framework Nanofilms.

Benefitting from the strong intrinsic nonlinear optical (NLO) property of the individual porphyrin molecule, the integration of porphyrin molecules into tightly aligned arrays may lead to intuitively promising high-performance materials of tailorable NLO effect. In order to verify this speculation, we prepare crystalline and highly oriented porphyrin-based surface-supported metal-organic framework nanofilms (SURMOFs) and then characterize their NLO performance. Results reveal that porphyrin-based SURMOFs exhibit the highest saturable absorption (SA) yet recorded with a third-order NLO absorption coefficient up to -10-3 cm/W, about 7 orders stronger than porphyrin solvents in which the porphyrin molecules are disordered, under a certain excitation strength. Further increasing the excitation strength shows that the NLO absorption property of the porphyrin-based SURMOFs can be effectively modulated from SA to reverse saturable absorption, followed by a reemerging SA. The multiple-stage NLO switching is assigned to the interplay of simultaneous one-photon SA, two-photon absorption, and two-photon SA effects. The superior and modulatable NLO property as well as the designable and ordered crystalline structure suggest that porphyrin-based SURMOFs might be employed as a new class of high-performance NLO materials with potential applications in novel optical switches or logic gates to realize the all-optical information process.

Design of novel inorganic alkaline earth metal doped aluminum nitride complexes (AEM@Al12N12) with high chemical stability, improved electronic properties and large nonlinear optical response

Aluminum nitride nanocages (Al12N12) doped with alkaline earth metals (Be, Mg, and Ca) are theoretically designed and their geometrical structures, electronic properties, and nonlinear optical responses are explored by using density functional theory (DFT) calculations. The results revealed that the doped complexes are thermodynamically quite stable, and alkaline earth metals effectively narrow the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energy gaps (EH-L) of the resultant complexes. More importantly, the adsorption of alkaline earth metal significantly increased the first hyperpolarizability (βo) values from 0 au of the pristine aluminum nitride nanocage up to 7769 au for the doped complexes. This study successfully demonstrates that the doping of alkaline earth metal on aluminum nitride nanocage is an effective approach to enhance electronic properties and NLO response of the system. In future these complexes can act as promising candidates to be used as high-performance nonlinear optical (NLO) materials for optoelectronic devices.

Doping superalkali on Zn12O12 nanocage constitutes a superior approach to fabricate stable and high-performance nonlinear optical materials

Fabrication of stable nonlinear optical materials is highly demanding due to their widespread applications in optical and optoelectronic devices. Novel inorganic complexes are theoretically designed and investigated by doping superalkalis on Zn12O12 cluster. The results reveal that doping causes shifting of excess electrons from superalkalis towards Zn12O12 cluster and enhances the NLO properties of these isomers. Moreover, the effect of doping different superalkalis (Li3O, Na3O and K3O) over Zn12O12 nanocages is also studied. All the isomers have shown excellent NLO response and are transparent under ultraviolet region of workable laser conditions. Comparative analysis reveals that hyperpolarizability shows monotonic dependence on atomic number of metal atom in the superalkalis. K3O@Zn12O12 exhibits the highest first hyperpolarizability (βo) value of 394,217 au. The band gap is reduced up to 70% as compared to pristine nanocage, making them n-type semiconductors. This study provides a pathway for designing thermally stable inorganic complexes as potential precursors for high-performance NLO materials.

A Theoretical Investigation on Second-Order NLO Properties of Organic Substitutions of [Mo6O19]<sup>2-</sup> and [MoW5O19]<sup>2-</sup>

In this study, density functional theory (DFT) was used to calculate second-order polarizabilities and second-order polarizabilities densities of a series of organic substitution for Lindqvist-type polyoxometalates (POMs), and the nonlinear optical (NLO) properties was also analyzed. We found that βzzz has the main contribution to β value. The expansion of molecular structure on z-axis greatly increased second-order polarizabilities. Both the size of the organic segments and metal hybridization exert an influence on β value. The analysis on the second-order polarizabilities density is used to explain the NLO phenomenon. In the present investigation, metal hybridization and π-conjugation changed the contribution of βzzz value from different parts. The results of this work will contribute to the potential applications in high-performance NLO materials.

First principle characterization of structural, electronic, mechanical, thermodynamic, linear and nonlinear optical properties of zinc blende InAs, InSb and their InAsxSb1-x ternary alloys

The structural and electronic properties of InAsxSb1-x ternary alloys are studied using plane-wave pseudopotential method based on the density functional theory. The Born effective charge, elastic constants, phonon dispersion curves, linear and nonlinear optical properties of these compounds are calculated using density functional perturbation theory. Based on the calculated phonon frequency, the specific heat at constant volume and entropy are obtained within the harmonic approximation. Moreover, due to the density functional theory band gap problem, the band gap correction is performed within the one-shot GW approximations. The distinguished role of In 4d states on the electronic energy band gap and nonlinear properties of these alloys are extensively explored by the comparison between the calculated results of Hartwigsen-Goedecker-Hutter and Trouiller-Martins-type pseudopotentials. The calculated results show that InAsxSb1-x alloys are mechanically stable and can be a good candidate for high-performance nonlinear optical material. The calculated results of InAs and InSb compounds are in acceptable agreement with available theoretical and experimental results, so the calculated results of InAsxSb1-x alloys will be helpful for future experimental and theoretical investigations.

Theoretical exploration of second-order nonlinear optical properties of mono- and bimetallic Pt(II) dithienylcyclopentene complexes: Ligands and photoisomerization effect

On the basis of great diverse applications of nonlinear optical (NLO) materials, organometallic complexes have attracted considerable attention. In this paper, we present a detailed investigation on a series of Pt(II) dithienylcyclopentene(DTE)-based complexes via density functional theory method with the aim of evaluating their structures, electronic absorption spectra and first hyperpolarizabilities. The calculations demonstrate that the first hyperpolarizabilities can be enhanced by the introduction of quinolone into the complexes because of the enlarged spatial separation of electron density. However, Pt(II) complexes containing perfluorocyclopentene ring exhibit decreasing NLO response attributed to lower amount of charge transferred and short effective CT distance. The static first hyperpolarizabilities (βtot) of monometallic Pt(II) complexes are larger than those of bimetallic Pt(II) complexes due to correlative mixed charge-transfer patterns. More importantly, the closed-ring (1c) complex comprising DTE unit exhibits the largest βtot value approaching 144 × 10−30 esu, with the contrast over five times compared to corresponding open-ring due to the better π-conjugated delocalization and smaller HOMO and LUMO energy gap. In general, we envision our work will be beneficial for further rational design of DTE-containing Pt(II) complexes as high performance NLO materials.