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Investigation on the photophysical properties of a series of promising phosphorescent iridium (III) complexes with modified cyclometalating ligands
摘要： Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were applied to investigate the electronic structures and photophysical properties of a series of phosphorescent iridium (III) complexes, [(C^N)2Ir(N^N)]+(PF6)(cid:2), in which C^N = 4-aryl-1-benzyl-1H-1, 2, 3-triazoles. Herein, aryl = phenyl, biphenyl, three-phenyl aromatic for complexes 1a, 2a, 3a (N^N = 2, 20-bipyridine) and aryl = 40, 60-di?uorophenyl, 60-?uoro-biphenyl, 60-?uoro-three-phenyl aromatic for complexes 1b, 2b, 3b (N^N = 4, 40-di-tert-butyl-2, 20-bipyridine), respectively. The geometric/electronic con?gurations, absorption/emission properties and phosphorescent performances have been outlined for each of the complexes. Based on the two simpli?cations presented in this paper and the available experimental data, the phosphorescent radiative rates for complexes 1a-3b were approximately obtained to be: 1.20 (cid:3) 106 s(cid:2)1, 1.68 (cid:3) 105 s(cid:2)1, 2.19 (cid:3) 107 s(cid:2)1, 3.85 (cid:3) 106 s(cid:2)1, 1.85 (cid:3) 107 s(cid:2)1 and 1.50 (cid:3) 107 s(cid:2)1, respectively. In view of the electroluminescent applications in OLED, our present research work is of great importance for the design and synthesis of organo-transition metal complexes with improved phosphorescent performances.
关键词： Phosphorescence,Photophysical properties,Time-dependent DFT,Iridium (III) complexes,Density functional theory (DFT)
更新于2025-09-19 17:15:36
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Dicyanovinyl substituted push–pull chromophores: effect of the central C=C/phenyl spacers, crystal structures and application in hydrazine sensing
摘要： To discern the distinctive effect of C=C bond and phenyl bridge on the photophysical and chemical properties of D?π?A molecular systems, three new dicyanovinyl substituted push–pull chromophores 1-3 containing either a C=C bond or a phenyl ring as the central π?linker, were synthesized by Suzuki-Miyaura and Knoevenagel reactions. Together with the counterpart of 1 developed by Zhang’s group (TPE-z), their optical properties and single crystal structures were systematically and comparatively investigated. Notably, the simple π–extension of a C=C linker to a phenyl ring between electron-donor and -acceptor moieties could greatly affect the photophysical properties of chromophores, particularly leading to significant hypsochromic shifts in both absorption and emission spectra. Meanwhile, as a node of twisted sections in chromophores, the C=C bond was demonstrated to play an important role in the nonradiative relaxation of excited states, as compared to the rigid phenyl spacer. Moreover, the three chromophores were found to display spectral responses to hydrazine with slightly different sensitivities and visual detection of hydrazine in gaseous state was achieved via using readily fabricated paper test strips.
关键词： C=C bond,hydrazine sensing,phenyl bridge,push-pull chromophores,photophysical properties,Dicyanovinyl
更新于2025-09-19 17:15:36
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Theoretical Studies of Photophysical Properties of Da????a??Aa????a??D-Type Diketopyrrolopyrrole-Based Molecules for Organic Light-Emitting Diodes and Organic Solar Cells
摘要： A series of D–π–A diketopyrrolopyrrole(DPP)-based small molecules were designed for organic light-emitting diode(OLEDs) and organic solar cell(OSCs) applications. Applying the PBE0/6-31G(d,p) method, the ground state geometry and relevant electronic properties were investigated. The first excited singlet state geometry and the absorption and fluorescent spectra were simulated at the TD-PBE0/6-31G(d,p) level. The calculated results revealed that the photophysical properties were affected through the introduction of different end groups. Furthermore, the electronic transitions corresponding to absorption and emission exhibited an intramolecular charge transfer feature. Our results suggest that the designed molecules acted not only as luminescent for OLEDs, but also as donor materials in OSCs. Moreover, they can also be used as potential electron transfer materials for OLEDs and OSCs.
关键词： photophysical properties,organic solar cells(OSCs),organic light-emitting diodes(OLEDs),diketopyrrolopyrrole(DPP)-based molecules,Charge transporting property
更新于2025-09-19 17:13:59
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Impact of Perovskite Composition on Film Formation Quality and Photophysical Properties for Flexible Perovskite Solar Cells
摘要： In recent years, ?exible perovskite solar cells have drawn tremendous attention in the ?eld of wearable devices, and optimization of perovskite composition plays an important role in improving ?lm quality and photophysical properties. At present, some researchers have only studied A-site organic cations mixing or X-site halide anions mixing in the ABX3 structure of perovskite, but there are few reports on co-mixing of A-site and X-site ions in ?exible perovskite solar cells. In this paper, we mainly try to study the e?ects of di?erent concentrations of mixed formamidine methylamine halide (FAxMA1-xBrxClyI1-x-y) precursor solutions on the quality and photophysical properties of perovskite ?lms under low temperature process. We conclude that the ?lm quality and photophysical properties reached the best results when the optimized precursor solution concentration was 60:6:6. The investigation on composition optimization in this experiment laid the foundation for the improvement of the performance of ?exible perovskite solar cells. We also use the results of this experiment to prepare ?exible perovskite solar cells based on carbon electrodes, which are expected to be applied in other ?exible optoelectronic or electro-optical devices.
关键词： photophysical properties,perovskite composition,?lm quality,?exible perovskite solar cells
更新于2025-09-19 17:13:59
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Investigation of Photophysical Properties of Ternary Zn–Ga–S Quantum Dots: Band Gap versus Sub-Band-Gap Excitations and Emissions
摘要： Highly luminescent ternary Zn?Ga?S quantum dots (QDs) were synthesized via a noninjection method by varying Zn/Ga ratios. X-ray diffraction and Raman investigations demonstrate composition-dependent changes with multiple phases including ZnGa2S4, ZnS, and Ga2S3 in all samples. Two distinct excitation pathways were identified from absorption and photoluminescence excitation spectra; among them, one is due to the band-gap transition appearing at around 375 and 395 nm, whereas another one observed nearby 505 nm originates from sub-band-gap defect states. Photoluminescence (PL) spectra of these QDs depict multiple emission noticeable at around 410, 435, 461, and 477 nm arising from crystallographic point defects formed within the band gap. The origin of these defects including zinc interstitials (IZn), zinc vacancies (VZn), sulfur interstitials (IS), sulfur vacancies (VS), and gallium vacancies (VGa) has been discussed in detail by proposing an energy-level diagram. Further, the time-dependent PL decay curve strongly suggests that the tail emission (appear around 477 nm) in these ternary QDs arises due to donor?acceptor pair recombination. This study enables us to understand the PL mechanism in new series of Zn?Ga?S ternary QDs and can be useful for the future utilization of these QDs in photovoltaic and display devices.
关键词： photophysical properties,ternary Zn?Ga?S quantum dots,sub-band-gap defect states,donor?acceptor pair recombination,photoluminescence,band-gap transition
更新于2025-09-16 10:30:52
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Amphiprotism-coupled NIR-Emission in Extended Pyrazinacenes containing Seven Linearly-fused Pyrazine Units
摘要： Peripherally substituted tetradecaazaheptacene (N14Hp) compounds, exhibiting amphiprotism-coupled emission, have been synthesized. X-ray crystallography reveals a planar acene-like chromophore, and electronic absorption and emission occur in the near infrared biological transparency window (650 – 900 nm). The compounds exhibit long wave emission with photoluminescence quantum yields ΦPL up to ~0.61 at 686 nm with monodeprotonated state ΦPL ~0.58 at 712 nm. This unprecedented highly nitrogenous chromophore illustrates the stability and utility of the pyrazinacenes for different applications based on their photophysical properties and chemical structures.
关键词： photophysical properties,NIR-emission,pyrazinacenes,amphiprotism,chromophore
更新于2025-09-16 10:30:52
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Photophysical and electronic properties of bismuth-perovskite shelled lead sulfide quantum dots
摘要： Metal halide perovskite shelled quantum dot solids have recently emerged as an interesting class of solution-processable materials that possess the desirable electronic properties of both quantum dots and perovskites. Recent reports have shown that lead sulfide quantum dots (PbS QDs) with perovskite ligand-shells can be successfully utilized in (opto)electronic devices such as solar cells, photoconductors, and field-effect transistors (FETs), a development attributed to the compatibility of lattice parameters between PbS and certain metal halide perovskites that results in the growth of the perovskite shell on the PbS QDs. Of several possible perovskite combinations used with PbS QDs, bismuth-based variants have been shown to have the lowest lattice mismatch and to display excellent performance in photoconductors. However, they also display photoluminescence (PL), which is highly sensitive to surface defects. In this work, we present an investigation of the transport and optical properties of two types of bismuth-based perovskite (MA3BiI6 and MA3Bi2I9) shelled PbS QDs. Our photophysical study using temperature-dependent PL spectroscopy between 5 and 290 K indicates that the PL efficiency of the reference oleic acid (OA) capped samples is much higher than that of the Bi-shelled ones, which suffer from traps, most likely formed at their surfaces during the phase-transfer ligand exchange process. Nevertheless, the results from electrical measurements on FETs show the successful removal of the native-OA ligands, displaying electron dominated transport with modest mobilities of around 10?3 cm2 [V s]?1 – comparable to the reported values for epitaxial Pb-based shelled samples. These findings advance our understanding of perovskite shelled QD-solids and point to the utility of these Bi-based variants as contenders for photovoltaic and other optoelectronic applications.
关键词： field-effect transistors,bismuth-perovskite,electronic properties,photoluminescence,photophysical properties,lead sulfide quantum dots
更新于2025-09-12 10:27:22
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Synthesis of new simple hole-transport materials bearing benzodithiazole based core for perovskite solar cells
摘要： Benzo[c][1,2,5]thiadiazole(BT) core-based novel organic hole-transport materials (HTMs) BTT-PMe and BTT-2F are successfully synthesized for perovskite solar cells. The new HTMs are prepared by the simpler synthetic route with cost-effective purification steps. These HTMs are structurally confirmed by NMR, FT-IR and mass spectroscopy. The optical parameters are analysed using the UV–Vis spectrophotometer and cyclic voltammetry. To further confirmation of these properties we conducted the theoretical studies, which are fully matched with the experimental data. We have studied the effect of fluorine atom for its photo physical properties.
关键词： Photophysical properties,Perovskite solar cells,Benzo[c][1,2,5]thiadiazole,Hole-transport materials (HTMs)
更新于2025-09-12 10:27:22
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Molecular Packing and Solid-state Fluorescence of Conjugated Compounds of Carbazole-acrylonitrile Derivatives
摘要： In this review paper, have been investigated three novel crystal structures of three molecules with carbazole substituents as the electron-donor group. These molecules, 2-(phenyl)-3-(N-ethyl-(3'-carbazolyl))acrylonitrile (I), 2-(3''-pyridyl)-3-(N-ethyl-(3'-carbazolyl))acrylonitrile (II), and 2-(4-pyridyl)-3-(N-ethyl-(3′-carbazolyl))acrylonitrile (III) in their structure, possess the electron-donor carbazole moiety, a -CN group attached to the double bond, and a phenyl or a pyridine function at the meta- or para-position. It was revealed with the help of single crystal diffraction X-ray analysis that there exists no difference in the crystal system, because all the compounds were crystallized in monoclinic system with space group P21/c. For determining the effect of the position of the nitrogen atom substitution on the crystal properties, has been analyzed and contrasted the molecular packing in a single crystal with that of other previously reported carbazole derivatives. The double bond bearing N-ethylcarbazole,–CN, phenyl or pyridine groups was observed to impart sufficient polarity in order to show slipped π-stacking aggregation in the solid state, affecting the compounds in the solid state and consequently affecting their fluorescence properties. The substitution at the para position was reported to exhibit more multiple C-H...π interactions as well as an interesting and unexpected short contact distance between adjacent N...N molecules those brought a conformational change resulting in an edge-to-face alignment in the molecules and affecting the best relative photoluminescence efficiency of the sample.
关键词： crystal structures,aggregation,cyano-substituted,Acrylonitrile derivatives,N-carbazole-acrylonitriles photophysical properties,TD-DFT calculations,pyridine derivatives
更新于2025-09-11 14:12:44
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Effect of substituents on photophysical and aggregation behaviour in quinoline based bis-terpyridine Zn(II) complexes
摘要： Synthesis of the terpyridine based novel Zn(II) complexes (C1-C3) have been described. Characterization of these complexes has been achieved by spectroscopic studies (IR, 1H, 13C, 19F, HRMS, UV/Vis and fluorescence) and structure of C1 determined by X-ray single crystal analyses. Cautious tuning by incorporating appropriate substituents (–H; C1, –CH3; C2 and –OCH3; C3) enabled the complexes to exhibit solvent dependent emission indicative of more polarized excited state probably due to enhanced intramolecular charge transfer (ICT). Occurrence of aggregation induced emission (AIE) in C3 has been validated by solid state emission and vital role of RIR in inducing AIE upon aggregation by fluorescence lifetime experiments. The role of solvent and substituents on photophysical behaviour and morphology of the complexes has been investigated by UV/Vis, emission and scanning electron microscopy (SEM). As well, lowering of the energy gap between HOMO and LUMO by electron donating substituents –CH3 (C2) and –OCH3 (C3) has been supported by DFT studies.
关键词： Zn(II) complexes,photophysical properties,DFT studies,aggregation induced emission,terpyridine
更新于2025-09-10 09:29:36