Showing papers on "Hyperpolarizability published in 2022"

Design and synthesis of chromophores with enhanced electro-optic activities in both bulk and plasmonic–organic hybrid devices

Abstract: This study demonstrates enhancement of in-device electro-optic activity via a series of theory-inspired organic electro-optic (OEO) chromophores based on strong (diarylamino)phenyl electron donating moieties. These chromophores are tuned to minimize trade-offs between molecular hyperpolarizability and optical loss. Hyper-Rayleigh scattering (HRS) measurements demonstrate that these chromophores, herein described as BAH, show >2-fold improvement in β versus standard chromophores such as JRD1, and approach that of the recent BTP and BAY chromophore families. Electric field poled bulk devices of neat and binary BAH chromophores exhibited significantly enhanced EO coefficients (r33) and poling efficiencies (r33/Ep) compared with state-of-the-art chromophores such as JRD1. The neat BAH13 devices with charge blocking layers produced very large poling efficiencies of 11.6 ± 0.7 nm2 V−2 and maximum r33 value of 1100 ± 100 pm V−1 at 1310 nm on hafnium dioxide (HfO2). These results were comparable to that of our recently reported BAY1 but with much lower loss (extinction coefficient, k), and greatly exceeding that of other previously reported OEO compounds. 3 : 1 BAH-FD : BAH13 blends showed a poling efficiency of 6.7 ± 0.3 nm2 V−2 and an even greater reduction in k. 1 : 1 BAH-BB : BAH13 showed a higher poling efficiency of 8.4 ± 0.3 nm2 V−2, which is approximately a 2.5-fold enhancement in poling efficiency vs. JRD1. Neat BAH13 was evaluated in plasmonic–organic hybrid (POH) Mach–Zehnder modulators with a phase shifter length of 10 μm and slot widths of 80 and 105 nm. In-device BAH13 achieved a maximum r33 of 208 pm V−1 at 1550 nm, which is ∼1.7 times higher than JRD1 under equivalent conditions.

Design and synthesis of chromophores with enhanced electro-optic activities in both bulk and plasmonic–organic hybrid devices

Abstract: This study demonstrates enhancement of in-device electro-optic activity via a series of theory-inspired organic electro-optic (OEO) chromophores based on strong (diarylamino)phenyl electron donating moieties. These chromophores are tuned to minimize trade-offs between molecular hyperpolarizability and optical loss. Hyper-Rayleigh scattering (HRS) measurements demonstrate that these chromophores, herein described as BAH, show >2-fold improvement in β versus standard chromophores such as JRD1, and approach that of the recent BTP and BAY chromophore families. Electric field poled bulk devices of neat and binary BAH chromophores exhibited significantly enhanced EO coefficients (r33) and poling efficiencies (r33/Ep) compared with state-of-the-art chromophores such as JRD1. The neat BAH13 devices with charge blocking layers produced very large poling efficiencies of 11.6 ± 0.7 nm2 V-2 and maximum r33 value of 1100 ± 100 pm V-1 at 1310 nm on hafnium dioxide (HfO2). These results were comparable to that of our recently reported BAY1 but with much lower loss (extinction coefficient, k), and greatly exceeding that of other previously reported OEO compounds. 3 : 1 BAH-FD : BAH13 blends showed a poling efficiency of 6.7 ± 0.3 nm2 V-2 and an even greater reduction in k. 1 : 1 BAH-BB : BAH13 showed a higher poling efficiency of 8.4 ± 0.3 nm2 V-2, which is approximately a 2.5-fold enhancement in poling efficiency vs. JRD1. Neat BAH13 was evaluated in plasmonic-organic hybrid (POH) Mach-Zehnder modulators with a phase shifter length of 10 μm and slot widths of 80 and 105 nm. In-device BAH13 achieved a maximum r33 of 208 pm V-1 at 1550 nm, which is ∼1.7 times higher than JRD1 under equivalent conditions.

Synthesis of Crystalline Fluoro-Functionalized Imines, Single Crystal Investigation, Hirshfeld Surface Analysis, and Theoretical Exploration

Abstract: This investigation is focused on the synthesis of two halo-functionalized crystalline Schiff base (imine) compounds: (E)-2-methoxy-6-(((3-(trifluoromethyl)phenyl)imino)methyl)phenol (MFIP) and (E)-1-(((2-fluorophenyl)imino)methyl)naphthalen-2-ol (FPIN) by the condensation reaction of substituted benzaldehydes and substituted aniline. The crystal structures of MFIP and FPIN were determined unambiguously by single-crystal X-ray diffraction (SC-XRD) studies. Intermolecular interactions and the role of fluorine atoms in the stabilization of the crystal packing are explored for both compounds using Hirshfeld surface analysis. Accompanied with experimental studies, quantum chemical calculations were also performed for comprehensive structure elucidation at the M06/6-311G(d,p) level of theory. A comparison of experimental and density functional theory results for geometrical parameters exhibited excellent agreement. Interestingly, Frontier molecular orbitals and natural bond orbital (NBO) findings revealed that intramolecular charge transfer and hyper-conjugation interactions had played a significant role to stabilize the molecules. Both compounds exhibited a relatively larger value of hardness with a smaller global softness, which, as proposed by the SC-XRD and NBO study, shows a higher stability. Nonlinear optical (NLO) findings showed that FPIN manifested a larger value of linear polarizability ( = 293.06 a.u.) and second-order hyperpolarizability ( = 3.31 × 105 a.u.) than MFIP ( = 252.42 and = 2.08 × 105 a.u.) due to an extended conjugation. The above-mentioned findings of the entitled compounds may play a crucial role in NLO applications.

Enriching NLO efficacy via designing non-fullerene molecules with the modification of acceptor moieties into ICIF2F: an emerging theoretical approach

Abstract: Non-fullerene (NF)-based compounds have attracted much attention as compared to fullerene-based materials because of their promising optoelectronic properties, lower synthetic cost and greater stability. Usually, the end-capped groups have a promising impact in magnifying the nonlinear optical (NLO) characteristics in the non-fullerene molecules. Based on this, a series of new NLO active non-fullerene molecules (NFAD2–NFAD6) have been established. The non-fullerene molecules (NFAD2–NFAD6) were designed by end-capped modification in acceptor moieties of the reference (NFAR1), while donor and π-bridge moieties were kept the same in the entire series. Quantum chemistry-based calculations at the M06/6-311G(d,p) level were done to determine the NLO characteristics and for other supportive analyses. The acceptor and donor moieties were utilized at the opposite terminals of NFAD2–NFAD6, which proved to be an effective approach in tuning the FMO band gap. Overall the results of natural bond orbital (NBO), density of state (DOS) and transition density matrices (TDMs) analyses supported the NLO properties of the designed compounds. Among all the studied compounds, NFAD4 was proven to be the most suitable candidate due to its promising NLO properties, well supported by a lower bandgap of 1.519 eV and a maximum absorption wavelength of 999.550 nm. Therefore, NFAD4 was reported with greater amplitude of dipole polarizability (10.429 e.s.u), average polarizability (2.953 × 10−22 e.s.u), first hyperpolarizability (13.16 × 10−27 e.s.u.) and second hyperpolarizability (2.150 × 10−31 e.s.u.) than other derivatives and NFAR1. Subsequently, the present study depicted the significance of utilizing different non-fullerene (NF)-based acceptor moieties to achieve the promising NLO material. This computational study may lead towards new plausible pathways for researchers to design potent NLO substances for impending hi-tech applications.

Heteroanionic Melilite Oxysulfide: A Promising Infrared Nonlinear Optical Candidate with a Strong Second-Harmonic Generation Response, Sufficient Birefringence, and Wide Bandgap.

Abstract: The achievement of balanced performance with a strong second-harmonic generation (SHG) response, proper birefringence, and wide band gap concurrently is a crucial but challenging task in infrared nonlinear optical (IR-NLO) crystals. Here, we theoretically confirmed that the heteroanionic oxysulfide tetrahedron would produce improved polarizability anisotropy and quadratic hyperpolarizability compared with the monoanionic oxide or sulfide tetrahedra. When this anion-mixing strategy was applied, melilite oxysulfide with the four representative members A2GeGa2OS6 (A = Ca, Sr) and Sr2MGe2OS6 (M = Zn, Cd) was successfully discovered as a promising IR-NLO material system. Remarkably, compared with the monoanionic melilite oxides, these compounds exhibited unbiased performances of proper birefringences (0.106-0.143), strong SHG responses (>10× melilite oxide Ba2CdGe2O7, 1.3-2.1× AgGaS2 (AGS) @1570 nm) with phase-matchable ability, wide band gaps (2.95-3.15 eV), and large laser-induced damage thresholds (LIDTs, 5.6-13.4× AGS). The high structure tolerance of melilite offers a great possibility to improve the SHG response via tuning the orbital composition and hybridization near band edges. This work provides an effective approach for the design of high-performance IR-NLO materials.

Noncentrosymmetric Rare-Earth Borate Fluoride La2B5O9F3: A New Ultraviolet Nonlinear Optical Crystal with Enhanced Linear and Nonlinear Performance.

Abstract: In crystal engineering, it is an effective and controllable approach to modify the electronic band structure and optimize crystal performances using rational chemical cosubstitution in a classic structure model. Herein, the noncentrosymmetric (NCS) rare-earth borate fluoride La2B5O9F3 was designed and synthesized successfully based on the extraordinarily stable M2B5O9X (M = Ca, Sr, Ba, Sn, Pb, and Eu; X = Cl, Br, and I) template. Moreover, all 70 rare-earth borate halides were discussed, and the ratio of crystallization in NCS group is only 17.1%, much lower than 34.9% in all anhydrous borates. Benefiting from the substitution of [MOX] by [LaOF] polyhedra with improved hyperpolarizability and anisotropy of polarizability, compared with the M2B5O9X family, La2B5O9F3 with optimized band structure exhibits the suitable SHG response (1.2 × KH2PO4 (KDP) @ 1064 nm), large band gap (6.58 eV), and moderate birefringence, which well achieves the optimal balance among the three critical parameters mentioned above for nonlinear optical (NLO) applications in the short-wavelength region. This work expands the research field of NLO materials to rare-earth borate fluorides and can lead to a better understanding of the role of rare-earth metal cations.

Donor moieties with D–π–a framing modulated electronic and nonlinear optical properties for non-fullerene-based chromophores

Abstract: Herein, a series of non-fullerene-based substantial chromophores (FHD1–FHD6) with a D–π–A framework was designed from a synthesized non-fullerene compound (FH) via structural tailoring with various donor moieties. The FH and its designed derivatives were optimized with frequency analysis at the M06/6-311G (d,p) level to confirm their true minima on potential energy surfaces. These optimized geometries were utilized to perform further analyses, such as absorption, natural bonding orbital (NBO), frontier molecular orbital (FMO), and nonlinear orbital (NLO) analyses at the aforesaid level. Quantum chemical study revealed that all the designed chromophores exhibited a lower band gap than that of the parent molecule with the exception of FHD3. Furthermore, density of states (DOS) analysis supported the findings from the FMO study, and this agreement revealed that the efficient charge was transferred from the HOMO to the LUMO. The NBO investigations disclosed that all the compounds comprised donor moieties with positive charges and acceptors having negative charges. Interestingly, π-conjugated linkers were also found with positive charges, showing an effective donating property. These NBO findings explicated that FHD1–FHD6 exhibited an efficient push–pull mechanism. The λmax values of the designed chromophores were observed to be greater than the reference compound. The average polarizability 〈α〉, first hyperpolarizability (βtot), and second hyperpolarizability 〈γ〉 values of FHD2 were found to be 2.170 × 10−22, 3.150 × 10−27, and 4.275 × 10−32 esu, respectively, while all the other derivatives had been reported in the relevant range. Efficient NLO data revealed that FH-based derivatives may contribute significantly toward NLO technology.

Ultrawide Bandgap and Outstanding Second-Harmonic Generation Response by a Fluorine Enrichment Strategy at a Transition-Metal Oxyfluoride Nonlinear Optical Material.

Abstract: The development of nonlinear optical (NLO) materials has been hindered by competing microstructure requirements: the need to simultaneously engineer a large hyperpolarizability (a large second-harmonic generation (SHG)) and a wide HOMO-LUMO gap (a wide bandgap). Herein, a non-centrosymmetric transition-metal (TM) oxyfluoride K5(NbOF4)(NbF7)2 (KNOF) with an extremely high F/O ratio is constructed in high yield. KNOF exhibits an extremely wide bandgap (5.88 eV) and a strong powder SHG response (4.0 × KH2PO4) - both being the largest values for TM-centered oxyfluorides - as well as a birefringence sufficient for applications. The dominant roles of the partially fluorinated [NbO2F4] and totally fluorinated [NbF7] groups in achieving the enlarged bandgap in KNOF have been clarified by first-principles calculations. Our results suggest that maximizing the fluorine content of oxyfluorides may unlock the promise of short-wavelength-transparent materials with exceptional NLO performance.

Deciphering the Role of Alkali Metals (Li, Na, K) Doping for Triggering Nonlinear Optical (NLO) Properties of T-Graphene Quantum Dots: Toward the Development of Giant NLO Response Materials

Abstract: Nanoscale nonlinear optical (NLO) materials have received huge attention of the scientists in current decades because of their enormous applications in optics, electronics, and telecommunication. Different studies have been conducted to tune the nonlinear optical response of the nanomaterials. However, the role of alkali metal (Li, Na, K) doping on triggering the nonlinear optical response of nanomaterials by converting their centrosymmetric configuration into noncentrosymmetric configuration is rarely studied. Therefore, to find a novel of way of making NLO materials, we have employed density functional theory (DFT) calculations, which helped us to explore the effect of alkali metal (Li, Na, K) doping on the nonlinear optical response of tetragonal graphene quantum dots (TGQDs). Ten new complexes of alkali metal doped TGQDs are designed theoretically. The binding energy calculations revealed the stability of alkali metal doped TGQDs. The NLO responses of newly designed complexes are evaluated by their polarizability, first hyperpolarizability (βo), and frequency dependent hyperpolarizabilities. The Li@r8a exhibited the highest first hyperpolarizability (βo) value of 5.19 × 105 au. All these complexes exhibited complete transparency in the UV region. The exceptionally high values of βo of M@TGQDs are accredited to the generation of diffuse excess electrons, as indicated by NBO analysis and PDOS. NCI analysis is accomplished to examine the nature of bonding interactions among alkali metal atoms and TGQDs. Our results suggest alkali metal doped TGQD complexes as potential candidates for nanoscale NLO materials with sufficient stability and enhanced NLO response. This study will open new doors for making giant NLO response materials for modern hi-tech applications.