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Steady Enhancement in Photovoltaic Properties of Fluorine Functionalized Quinoxaline-Based Narrow Bandgap Polymer
摘要： To investigate the influence of fluoride phenyl side-chains onto a quinoxaline (Qx) unit on the photovoltaic performance of the narrow bandgap (NBG) photovoltaic polymers, herein, two novel NBG copolymers, PBDTT-DTQx and PBDTT-DTmFQx, were synthesized and characterized. 2-ethylhexylthiothiophene-substituted benzodithiophene (BDTT), 2,3-diphenylquinoxaline (DQx) [or 2,3-bis(3-fluorophenyl)quinoxaline (DmFQx)] and 2-ethylhexylthiophene (T) were used as the electron donor (D) unit, electron-withdrawing acceptor (A) unit and π-bridge, respectively. Compared to non-fluorine substituted PBDTT-DTQx, fluoride PBDTT-DTmFQx exhibited a wide UV-Vis absorption spectrum and high hole mobility. An enhanced short-circuit current (Jsc) and fill factor (FF) simultaneously gave rise to favorable efficiencies in the polymer/PC71BM-based polymer solar cells (PSCs). Under the illumination of AM 1.5G (100 mW cm?2), a maximum power conversion efficiency (PCE) of 6.40% was achieved with an open-circuit voltage (Voc) of 0.87 V, a Jsc of 12.0 mA cm?2 and a FF of 61.45% in PBDTT-DTmFQx/PC71BM-based PSCs, while PBDTT-DTQx-based devices also exhibited a PCE of 5.43%. The excellent results obtained demonstrate that PBDTT-DTmFQx by fluorine atom engineering could be a promising candidate for organic photovoltaics.
关键词： quinoxaline,synthesis,polymer solar cells,bulk heterojunction,narrow bandgap conjugated polymer
更新于2025-11-19 16:56:42
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Proton Triggered Colorimetric and Fluorescence Response of a Novel Quinoxaline Compromising a Donor-Acceptor System
摘要： Quinoxaline-based novel acid-responsive probe Q1 was designed on the basis of a conjugated donor-acceptor (D-A) subunit. Q1 shows colorimetric and fluorometric changes through protonation and deprotonation in dichloromethane. With the addition of the trifluoroacetic acid (TFA), UV-vis absorption spectral changes in peak intensity of Q1 was observed. Moreover, the appearance of a new peaks at 284 nm 434 nm in absorption spectra with the addition of TFA indicating protonation of quinoxaline nitrogen and form Q1.H+ and Q1.2H+. The emission spectra display appearance of new emission peak at 515 nm. The optical property variations were supported by time resolved fluorescence studies. The energy band gap was calculated by employing cyclic voltammetry and density functional calculations. Upon addition of triethylamine (TEA) the fluorescence emission spectral changes of Q1 are found to be reversible. Q1 shows color changes from blue to green in basic and acidic medium, respectively. The paper strip test was developed for making Q1 a colorimetric and fluorometric indicator.
关键词： proton sensor,quinoxaline,fluorescent,colorimetric,reversible sensor
更新于2025-11-19 16:46:39
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Effect of cyano substituent on photovoltaic properties of quinoxaline-based polymers
摘要： Three donor-acceptor type quinoxaline-based conjugated polymers, in which electron-donating indacenodithiophene (IDT) and indacenodithieno[3,2-b]thiophene (IDTT) were connected to the electron-accepting 2,3-diphenylquinoxaline (DPQ) derivatives, were synthesized using the Stille coupling reaction. To investigate the effects of the strong electron-withdrawing cyano (CN) substituent on the photovoltaic properties of polymers, it was selectively introduced in the DPQ unit on the polymer backbone. The combination of IDT and the standard DPQ produced the reference polymer IDT-Qx, while the coupling of IDT and IDTT with mono-CN substituted DPQ provided the target polymers IDT-QxCN and IDTT-QxCN, respectively. Owing to the significant contributions of the CN substituent, IDT-QxCN and IDTT-QxCN exhibited better photovoltaic performances than IDT-Qx reference. Furthermore, the presence of more planar two thieno[3,2-b] thiophenes in IDTT than the two thiophenes in IDT allowed IDTT-QxCN to display the highest power conversion efficiency (5.47%) with an open circuit voltage of 0.95 V, short-circuit current density of 15.30 mA cm?2, and fill factor of 56.95%.
关键词： Quinoxaline,Indacenodithiophene,Cyano substituent,Indacenodithieno[3,2-b]thiophene
更新于2025-09-23 15:21:01
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Theoretical investigation using DFT of quinoxaline derivatives for electronic and photovoltaic effects
摘要： Photovoltaic properties of solar cells based on fifteen organic dyes have been studied in this work. B3LYP/6-311G (d,p) methods are realized to obtain geometries and optimize the electronic properties, optical and photovoltaic parameters for some quinoxaline derivatives. The results showed that time dependent DFT investigations using the CAM-B3LYP method with the polarized split-valence 6-311G (d,p) basis sets and the polarizable continuum model PCM model were sensibly able to predict the excitation energies, the spectroscopy of the compounds. HOMO and LUMO energy levels of these molecules can make a positive impact on the process of electron injection and dye regeneration. Gaps energy ΔEg, short-circuit current density Jsc, light-harvesting efficiency LHE, injection driving force ΔGinject, total reorganization energy λtotal and open-circuit photovoltage Voc enable qualitative predictions about the reactivity of these dyes.
关键词： Computing methodology,TD-DFT,Energy,PCM,Optoelectronic,Particle physics,Quantum mechanics,Photovoltaic,Physics,Quinoxaline derivatives,Theoretical computer science,Solar cells,Molecular physics
更新于2025-09-23 15:19:57
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An iminodibenzyl–quinoxaline–iminodibenzyl scaffold as a mechanochromic and dual emitter: donor and bridge effects on optical properties
摘要： The influence of phenyl linkage and donor strength on the photophysical properties of new derivatives of quinoxaline-containing iminodibenzyl and iminostilbene moieties is studied. The donor–acceptor derivatives showed dual thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) despite a large energy gap between the excited singlet and triplet states (ca. 0.5 eV). This extremely rare observation is explained by the twisted and rigidified structure of the iminodibenzyl moiety.
关键词： dual emitter,quinoxaline,room temperature phosphorescence,iminodibenzyl,optical properties,mechanochromic,bridge effects,thermally activated delayed fluorescence,donor
更新于2025-09-19 17:15:36
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Effect of Side Substituents Incorporated into <i>??</i> a??Bridges of Quinoxalinea??Based Sensitizers for Dyea??Sensitized Solar Cells
摘要： ZW003, has been synthesized and applied in dye-sensitized solar cells (DSSCs). Both dyes have broad absorption and large molar absorption coefficients. The sensitizer with the HQ core effectively restrains intermolecular aggregation owing to steric hindrance of numerous alkyl chains. A thienyl unit with or without a hexyl branch is used as a π-bridge. Incorporation of only thienyl groups as a π-bridge into the sensitizer increases the dye-loading amount on TiO2 film owing to the smaller molecular size. Using the ZW002 dye with the Co (II/III) redox couple results in DSSCs that exhibits a high photovoltaic conversion efficiency of 8.23% and short-circuit current density (Jsc) of 12.43 mA cm?2, an open-circuit voltage (Voc) of 960 mV, and a fill factor (FF) of 0.69. Although ZW003 shows a wider absorption range than that of ZW002, the two additional phenyl groups on the quinoxaline unit contributes to poorer performance (PCE of 7.43%) due to more serious dye aggregation.
关键词： Quinoxaline,Additional acceptors,Intermolecular aggregation,Dye-loading amount,Dye-sensitized solar cells
更新于2025-09-19 17:13:59
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Wide band-gap organic molecules containing benzodithiophene and difluoroquinoxaline derivatives for solar cell applications
摘要： Two new semiconducting organic small molecules, namely BDTQ-BDT(EH) and BDTQ-BDT(OC), were prepared by attaching electron accepting 2,3-didodecyl-6,7-difluoro-5,8-di(thiophen-2-yl)quinoxaline (DTQ) unit on 2,6-position of electron donating 4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b’]dithiophene (BDT(EH)) and 4,8-bis(octyloxy)-benzo[1,2-b:4,5-b’]dithiophene (BDT(OC)) units. Molecule BDTQ-BDT(EH) showed higher thermal stability (5% weight loss temperature, Td “349 jC), slightly lower band-gap (Eg “2.10 eV) and deeper highest occupied molecular orbital energy level (HOMO “–5.36 eV) level compared to those (Td “336 jC, Eg “2.11 eV, and HOMO “–5.30 eV, respectively.) of the molecule BDTQ-BDT(OC). The organic solar cells (OSCs) made with the synthesized molecules as an electron donor and [6,6]-phenyl C71 butyric acid methyl ester (PC70BM) as an electron acceptor gave a maximum power conversion efficiency (PCE) of 1.20% and 0.83%, respectively, for BDTQ-BDT(EH) and BDTQ-BDT(OC). This study confirmed that the substituents attached on the 4,8-position of BDT unit greatly alter the properties of the resulting molecules.
关键词： small molecule solar cells,wide band-gap molecules,quinoxaline-based molecules,benzodithiophene-based molecules,organic solar cells
更新于2025-09-16 10:30:52
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The effect of molecular structure on the properties of quinoxaline-based molecules for OLED applications
摘要： Different donor-acceptor-donor (D-A-D) and donor-π-bridge-acceptor-π-bridge-donor (D-π-A-π-D) systems based on quinoxaline acceptor are compared. A significant difference in electrochemical and photophysical properties was found depending on molecular structure. A luminescence shift from 539 nm up to 671 nm was observed upon extension of conjugation length. The studied compounds were tested in fluorescent organic light emitting diodes (OLEDs) demonstrating an external quantum efficiency up to 4.5 % for the deep red non-doped device and 7% for the doped into the exciplex host device. A quantum-chemical interpretation of the electroluminescence spectra for the fabricated OLEDs was carried out including modelling of excimers and exciplexes.
关键词： OLEDs,conjugation length,Quinoxaline,donor-acceptor,organic emitter,exciplex
更新于2025-09-12 10:27:22
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Designing a thiophene-fused quinoxaline unit to build D–A copolymers for non-fullerene organic solar cells
摘要： In this work, a kind of thiophene-fused quinoxaline (QXT) unit has been designed and synthesized as an electron-deficient unit to build two D-A conjugated copolymers (PBDTT-QXT-TF1 and PBDTT-QXT-TF2) with a thiophene ring as "π-bridge" and thienyl substituted benzo[1,2-b:4,5-b’]dithiophene (BDTT) unit as an electron-rich unit, in which two adjacent side-chain thiophene rings with different number of fluorine atoms have been introduced at 2,3-position of QXT unit. It is found that the fusion of a thiophene ring onto QX unit can result in a red-shift of absorption and narrow the optical bandgap through stabilizing the quinoid structure of the conjugated backbone, and the introduction of carboxyl group at the fused thiophene can reduce the HOMO energy level that is favorable for the enhancement of VOC of the organic solar cells (OSCs). However, the introduction of fused thiophene ring results in partially twist of conjugated backbone, thus attenuating the intramolecular charge transfer (ICT) absorption intensity and finally lead to the decrement of the JSC for the OSCs. Therefore, the corresponding OSC devices based on the PBDTT-QXT-TF1 or PBDTT-QXT-TF2 with IDIC acceptor show much high VOC but low JSC. In addition, the introduction of side-chain thiophene rings with different number fluorine atoms also regulates the energy levels and the structural crystallinity, thus further influencing the photovoltaic performances. By comparison, the PBDTT-QXT-TF1:IDIC blended film exhibits higher and more balanced hole/electron charge mobilities than the PBDTT-QXT-TF2:IDIC blended film, and PBDTT-QXT-TF1:IDIC based device shows higher power conversion efficiency (PCE) of 6.67 % (VOC = 0.951V, JSC =11.56 mA cm?2 and FF = 60.65 %) than PBDTT-QXT-TF2:IDIC based device with a PCE of 5.12 % (VOC = 0.975V, JSC = 9.78 mA cm?2 and FF = 53.61 %).
关键词： Thiophene-fused quinoxaline,Organic solar cells,Photovoltaic performances,D-A copolymer
更新于2025-09-12 10:27:22
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Deep Red Iridium(III) Complexes Based on Pyrene-Substituted Quinoxaline Ligands for Solution-Processed Phosphorescent Organic Light-Emitting Diodes
摘要： In this paper, we systemically investigated the photoelectric properties of three new deep-red quinoxaline-based iridium(III) complexes: Ir-0, Ir-1, and Ir-2. (MPQ)2Ir(dpm) (Ir-0) bore a 2-methyl-3-phenyl-quinoxaline cyclometalated ligand, while (c-PyMPQ)2Ir(dpm) (Ir-1) and (t-PyMPQ)2Ir(dpm) (Ir-2) possessed a 1-pyrene substituent that connected at the 6/7 position of the corresponding ligands. The configurations of the latter two complexes were well-confirmed by single-crystal X-ray diffraction, and both of them had large dihedral angles between the quinoxaline and pyrene units, preventing the emission peaks of the three complexes from being altered too much. Based on the density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations, we concluded that the emission of all complexes originated predominantly from the triplet metal-to-ligand/intraligand charge transfer (3MLCT/3ILCT) state of the non-pyrene-substituted counterpart Ir-0 core. Interestingly, we also obtained another type of pyrene-stacking characteristic crystal of Ir-1, which had an emission resembled the phosphorescence observed in thin film. The easily formed pyrene-stacking configuration would most probably limit their device performance at a higher concentration. Moreover, the fabricated organic light-emitting diodes (OLEDs) using these materials achieved considerable device performance at a low doping concentration of 0.5 wt %. This work provides an approach for reasonably designing large fused-ring-substituted quinoxaline ligands of iridium complexes.
关键词： Pyrene-Substituted Quinoxaline Ligands,Deep Red Iridium(III) Complexes,Solution-Processed Phosphorescent Organic Light-Emitting Diodes
更新于2025-09-12 10:27:22