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Facile color tuning of thermally activated delayed fluorescence by substituted ortho-carbazole-appended triarylboron emitters
摘要： We report the facile tuning of the emission color of thermally-activated delayed fluorescent (TADF) emitters based on an ortho-carbazole-appended triarylboron. A series of ortho-carbazole-appended triarylboron compounds (2-7) are prepared by introducing various electron-accepting substituents, such as phenyl, pyridyl, pyrimidyl, diphenylphosphine oxide, cyano, and dimesitylboryl groups, to the phenylene ring of the dimesitylphenylboryl (PhBMes2) acceptor moiety in the parent ortho-carbazole-appended triarylboron (CzoB, 1). The X-ray crystal structure of the cyano-substituted compound 6 confirms the twisted connectivity between the Cz and phenylene rings. All the compounds exhibit strong TADF (ΦPL = 48-93% in toluene) with large delayed portions. In particular, the emission bands gradually undergo bathochromic shifts from blue (l PL = 463 nm for 1) to greenish yellow (l PL = 532 nm for 7) depending on the electron-accepting substituents. Electrochemical studies show that the greater stabilization of the LUMO level compared to the HOMO is responsible for the red shifts of the emission. Theoretical studies further support the observed bathochromic shifts in the emission, as well as the small energy splittings (D EST) between the excited singlet and triplet states that afford the efficient TADF.
关键词： Ortho donor-acceptor,Color tuning,Triarylboron,Thermally activated delayed fluorescence
更新于2025-11-14 15:28:36
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Study of the photoresponse of a titanium anode coated with solution-processed fullerene-containing metal porphyrin/phthalocyanine films
摘要： The present paper deals with the recent studies on the preparation of porphyrin-based donor-acceptor complexes capable of photoinduced electron transfer for solution-processed organic solar cells. Here the synthesis and chemical structure of (octakis(3,5-di-tert-butylphenoxy)phthalocyaninato) cobalt(II) (1) and (2,3,7,8,12,18-hexamethyl,13,17-diethyl,5-(2-pyridyl)porphinato) manganese(III) chloride (2) are performed and self-assembly in toluene solution of 1 and 1′-N-methyl-2′-(pyridin-4-yl)pyrrolidino[3′,4′:1,2][60]fullerene (PyC60) were discussed in more details. The structure of the obtained dyad 1-PyC60 is con?rmed by means of chemical thermodynamics/kinetics, UV–vis, IR, 1H NMR spectroscopy. Photoelectrochemical studies of the phthalocyanine-fullerene dyad and its precursors were carried out by voltammetry and amperometry methods. A comparative analysis of the photoelectrochemical characteristics obtained in this paper and these for recent described cobalt(II)/manganese(III) porphyrin/phthalocyanine-fullerene dyads are introduced from which ideas for the future design of high performance organic solar cells will be developed.
关键词： donor-acceptor complexes,organic solar cells,phthalocyanine,photoinduced electron transfer,fullerene,porphyrin
更新于2025-11-14 15:14:40
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New copolymer involving PVK and F8BT for organic solar cells applications: Design, synthesis, characterization and theoretical studies
摘要： The new PVK-F8BT copolymer coupled to poly (9-vinylcarbazole) and poly(9,9-dioctyl?uorene-alt-benzothiadiazole) has been designed and elaborated by chemical oxidation for organic solar cells applications. Structural and photophysical properties were examined using di?erent and complementary techniques (Infrared, optical absorption, stationary and time resolved photoluminescence). The PVK-F8BT exhibited a broad absorption band covering the wavelength range from 200 nm to 700 nm covering the solar spectrum and, highlighting the charge transfer process. Moreover, the PVK-F8BT, showed a low band gap to be found to 1.9 eV and it average lifetime (2.62 ns) are longer than that of F8BT. The resulting copolymer exhibits original optical properties compared to the PVK and F8BT ones. The experimental analyses were coupled to theoretical calculations based on density functional theory and time-dependant density functional theory methods in order to better understand the structure-properties correlation. Furthermore DFT and TD-DFT calculations of the PVK-F8BT have been exploited to optimize the copolymer-based composites based on bulk heterojunction based organic photovoltaic copolymers with the 1-(3-methoxycarbonyl) propyl-1-phenyl-[6,6]–C61, as an acceptor. Thus, the band gap decreased to 1.69 eV, the power energy conversion e?ciency was about 7%. Our results have allowed us to discover a promising new photovoltaic material.
关键词： TD-DFT,Optical properties,Solar cells,Donor-acceptor,Charge transfer
更新于2025-10-22 19:40:53
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(Poly)terephthalates with Efficient Blue Emission in the Solid State
摘要： We prepared dimethyl and diaryl 2,5-dialkoxyterephthalates from dimethyl 2,5-dihydroxyterephthalate in good-to-high yields via alkylation or a sequence of alkylation, hydrolysis, chlorination, and condensation. The absorption spectra of the dialkoxyterephthalates contain a small band at 332–355 nm, which could be assigned to intramolecular charge-transfer transition from the alkoxy to alkoxycarbonyl groups on the basis of theoretical calculations using density functional theory. The dialkoxyterephthalates exhibited blue fluorescence with moderate-to-excellent quantum yields not only in solution but also in the solid state, such as a poly(methyl methacrylate) (PMMA) film and a powder. The solid-state quantum yields of the diisopropoxy-substituted terephthalates were similar or considerably higher than those of the dimethoxy-substituted counterparts. Copolymerization of 2,5-diisopropoxyterephthaloyl chloride and 1,4-butanediol with or without terephthaloyl chloride gave brilliantly blue fluorescent polymers, whose quantum yields were 0.72 and 0.71 in toluene and 0.46 and 0.40 in the neat film, respectively. Furthermore, white emission was achieved when a fluorescent yellow 2,5-diaminoterephthalate was doped into the thin film of the blue fluorescent polymer at 0.4 wt %.
关键词： materials science,arenes,donor-acceptor systems,conjugation,fluorescence
更新于2025-09-23 15:23:52
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Dithienobenzothiadiazole-Based Donor-Acceptor Polymer: Synthesis and Characterization for Organic Field-Effect Transistor
摘要： Conjugated polymers with coplanar conformation backbones can form a closer π-π stacking self-assembly in solid films, producing high charge-carrier mobility in organic field-effect transistors (OFETs). In this work, a new donor-acceptor (D-A) copolymer (PDTFBT-TVT) including (E)-2-(2-(thiophen-2-yl)vinyl)thiophene and dithienobenzothiadiazole conjugated units is synthesized via Stille copolymerization. It is found that PDTFBT-TVT has a good planar backbone structure with an optical band gap of 1.89 eV. Spun-cast film contains preferentially edge-on orientated polymer chains with respect to a polymer-treated SiO2 dielectric, yielding a hole mobility (μh) of 0.06 cm2 V-1 s-1 in OFET. Thermal annealing enhanced the π-conjugated ordering and orientation of PDTFBT-TVT chains in the spun-cast films. The annealed film-based OFETs show a considerable enhancement in μh up to 0.22 cm2 V-1 s-1, as well as high on/off current ratio of > 106.
关键词： organic field-effect transistor,donor-acceptor copolymer,dithienobenzothiadiazole
更新于2025-09-23 15:23:52
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Organic Transistor Based on Cyclopentadithiophene-Benzothiadiazole Donor-Acceptor Copolymer for the Detection and Discrimination between Multiple Structural Isomers
摘要： Distinguishing structural isomers is a critical and challenging task for biotechnology, chemical industry, and environmental monitoring. Approaches currently available are limited in terms of selectivity and simplicity. In this paper, a highly sensitive organic field-effect transistor (OFET) using the cyclopentadithiophene-benzothiadiazole (CDT-BTZ) copolymers as a semiconductor is presented for easy and selective detection of different families of structural isomers, as well as between different isomers within each family. High accuracy discrimination is achieved over a range of concentrations using only a single sensing parameter derived from the OFET characteristic transfer curve. As a reference, other homopolymer- and donor–acceptor copolymer-based OFET sensors are examined but do not have an equivalent sensing performance to that of the CDT-BTZ-based OFETs. Investigating the link between isomer absorption and swelling, supramolecular order and energy levels of the active layer reveals a unique effect of each isomer on the energy bands of the semiconducting polymer.
关键词： isomers,donor–acceptor copolymers,gas sensor,organic field-effect transistor,xylenes
更新于2025-09-23 15:23:52
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Electrochromic 2,4,6-triphenyl-1,3,5-triazine based esters with electron donor-acceptor structure
摘要： Ten tripod-shaped electrochromic materials (compound 1–10) were designed and synthesized by esterification of 4,4',4''-s-triazine-2,4,6-triyl-tribenzoic acid with different alcohols and phenols. These materials have a 2,4,6-triphenyl-1,3,5-triazine core and three ester side arms, forming an electron donor–π-acceptor structure. The electrochemical and optical properties of 1–10 were characterized by cyclic voltammetry and ultraviolet–visible spectroelectrochemistry. The conjugated structure of 1–10 markedly influenced their electrochemical properties. Electrochromic devices containing some of these compounds (1, 2, 4, 5, and 10) displayed intense color changes, fast switching times (<2 s), high optical contrast (>60%), good switching stability, high optical density (>1.0), and high coloring efficiency (>1000 cm2 C?1). The colored state of these devices strongly depended on the conjugated structure of the tripod-shaped component. Short chain lengths (compounds 1 and 2) and electron-donating groups (compounds 4, 5, 8, and 10) were beneficial to electrochromic properties, whereas a longer chain length (compound 3) and electron-withdrawing groups (compounds 6 and 9) adversely affected electrochromic properties.
关键词： Electron donor-acceptor structure,2,4,6-Triphenyl-1,3,5-triazine based esters,Tripod-shaped electrochromic materials,Electrochromic devices
更新于2025-09-23 15:23:52
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Single-Crystal Poly[4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b′]dithiophen-2-yl)- <i>alt</i> -[1,2,5]thiadiazolo[3,4- <i>c</i> ]pyridine] Nanowires with Ultrahigh Mobility
摘要： We fabricated single-crystal poly[4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b']-dithiophen-2-yl)-alt-[1,2,5]thiadiazolo-[3,4-c]pyridine] (PCDTPT) nanowires with ultrahigh mobility using a liquid-bridge-mediated nanotransfer molding method. The structural analysis of the single-crystal PCDTPT nanowires reveals that PCDTPT crystals have a triclinic structure, and the nanowires grow parallel to PCDTPT backbone chains, which provide important insights into its intrinsic charge transport. The single-crystal PCDTPT nanowire exhibits a superior charge carrier mobility of 72.94 ± 18.02 cm2 V-1 s-1 (maximum mobility up to 92.64 cm2 V-1 s-1), which is a record high value among conjugated polymers till date. In the single-crystal PCDTPT nanowire, the backbone chains in the linear structure along the nanowire growth axis lead to strong backbone delocalization, resulting in highly conductive polymer backbones and a drastic increase in charge carrier mobility. In addition, the single-crystal PCDTPT nanowire shows good environmental stability under air conditions compared to small-molecule organic semiconductors.
关键词： donor-acceptor-conjugated copolymers,liquid-bridge-mediated nanotransfer molding,PCDTPT,single-crystal polymer nanowire
更新于2025-09-23 15:23:52
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Contact Angle Relaxation and Long-lasting Hydrophilicity of Sputtered Anatase TiO <sub/>2</sub> Thin Films by Novel Quantitative XPS Analysis
摘要： The contact angle relaxation of TiO2 surfaces is an important problem that must be understood, particularly for long-lasting hydrophilicity under dark conditions. The relaxation of sputtered anatase TiO2 thin films over a long time (~22 days) in an atmospheric environment was observed using quantitative XPS analysis. A new peak was identified as H2O within a donor-acceptor complex at ~2.57 eV above the lattice oxygen peak. This donor?acceptor complex turns out to be a key factor for long lasting hydrophilicity, and our model is presented. Adventitious carbon contamination was not the main cause of the contact angle relaxation. Instead, samples with lower amounts of donor?acceptor complexes (IDAC/Ibulk ≤ ~5%) underwent contact angle relaxation over time, and samples with a high density of donor?acceptor complexes (IDAC/Ibulk ≥ ~10%) showed good hydrophilicity (contact angle ≤ 20°) over 22 days. Larger amounts of basic Ti?OH relative to acidic OHbridge (ITi?OH/Ibridge ≥ 1) resulted in greater amounts of donor?acceptor complexes (IDAC/Ibulk ≥ ~10%). Thus, basic Ti?OH groups interact with H2O by forming a strong electrostatic donor?acceptor complex, leading to long-lasting hydrophilicity. Indeed, TiO2 was transformed to show long lasting hydrophilicity by high-density oxygen plasma treatment by forming sufficient Ti?OH groups and H2O molecules in the donor?acceptor complexes. Contact angle relaxation is closely related to the interactions between water molecules and the TiO2 surface in the dark. It is suggested that the relaxation depends on the number of electrostatic donor?acceptor complexes. This study provides new insight by linking theoretical studies with the experimental contact angle at the TiO2 surface in an ambient environment and is the first study that provides the presented relaxation mechanism.
关键词： Hydrophilicity,Sputtering,Plasma treatment,Contact angle relaxation,XPS analysis,Donor-acceptor complex,TiO2 thin films
更新于2025-09-23 15:22:29
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Charge transfer processes and carrier dynamics at the pentacene - C60 interface
摘要： Heterostructures of pentacene (PEN) and Buckminsterfullerene (C60) are frequently attracting scientific interest as a well-defined small-molecule model-system for the study of internal interfaces between two organic semiconductors. They are prototypical representatives forming a donor-acceptor combination for studies of fundamental optoelectronic processes in organic photovoltaics. Despite their importance in exciton dissociation, the energetics of their interfacial charge-transfer (CT) states and their microscopic excitation dynamics are not yet clarified and still being discussed. Here, we present steady-state and time-resolved photoluminescence measurements on stacked heterostructures between these two materials. All experiments are performed in the visible and near-infrared spectral regions as CT states are expected at energies below the fundamental electronic transitions of the respective bulk materials. A characteristic, interface specific emission at around 1.13-1.17 eV is found, which we attribute to an interfacial CT state. Its excitation-energy dependence reveals the intricate relaxation dynamics of excitons formed in both constituent materials. Moreover, the analysis of the dynamics of the C60 excitons shows that the lifetime of this state is reduced in the presence of an interface with PEN. This quenching is attributed to a long-range interaction, i.e., the relaxation of excitations into the interfacial CT state.
关键词： organic heterostructures,charge-transfer exciton,light harvesting,donor-acceptor pair,Organic thin films,pentacene,fullerene
更新于2025-09-23 15:22:29