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Near-infrared-II photodetection realized by introducing organic-inorganic charge-transfer-complex photosensitive material into pentacene phototransistor
摘要： Organic phototransistor (OPT) is a promising photodetector with substantial attention due to its advantages such as low cost, light weight, flexibility and ease of large area preparation. Although the second near-infrared (NIR-II) window (1.0-1.7 microns) has important applications in fiber communication, the organic infrared photosensitive materials are scarce in this waveband, which greatly limits the application of organic photodetectors in near-infrared bands. In this work, a charge-transfer-complex (CTC) film with significant hyperchromic effect in the infrared range of 1000-1400 nm was prepared by co-evaporation of metal oxide WO3 and organic molecule m-MTDATA. A high performance near-infrared OPT was fabricated by combining this CTC photosensitive layer and pentacene (PENT) high-mobility channel layer, the photoresponsivity R of which has surpassed the recent reported level of 1.1 micron band inorganic infrared detector. The physical mechanism underlying the operation of CTC-PENT-OPT was clarified and the thickness of the CTC photosensitive film in this device was optimized. This new type of organic-inorganic CTC infrared-sensitive material will offer a new choice for the future study on organic infrared detectors.
关键词： Photodetection,Charge-transfer-complex,Pentacene,Near-infrared-II,Organic phototransistor
更新于2025-09-19 17:13:59
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Conjugated Polymer Controlled Morphology and Charge Transport of Small-Molecule Organic Semiconductors
摘要： In this study, we report an effective approach to tune the crystallization, microstructure and charge transport of solution-processed organic semiconductors by blending with a conjugated polymer additive poly(3-hexylthiophene) (P3HT). When 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) was used as a model semiconductor material to mix with different amount of P3HT, their intermolecular interactions led to distinctive TIPS pentacene film morphologies, including randomly-oriented crystal ribbons, elongated needles with enhanced long-range order, and grass-like curved microwires with interlinkages. Each type of morphology was found to further correlate to considerably different charge transport and device performance. As compared to pristine TIPS pentacene devices, bottom-gate, top-contact OTFTs with 2% in weight P3HT additive showed a 2-fold and 5-fold improvement of average field-effect mobility and performance consistency (defined as the ratio of average mobility to the standard deviation), respectively. The improvement in transistor electrical performance can be attributed to the combined effect of enhanced crystal orientation and uniformity, as well as increased areal coverage. This work can be applied beyond the particular example demonstrated in this study and to tune the charge transport of other small-molecule organic semiconductors in general.
关键词： OTFTs,TIPS pentacene,organic semiconductors,film morphology,P3HT,charge transport,conjugated polymer
更新于2025-09-19 17:13:59
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Systematic control of the rate of singlet fission within 6,13-diphenylpentacene aggregates with PbS quantum dot templates
摘要： Lead chalcogenide quantum dots (QDs) are promising acceptors for photovoltaic devices that harness the singlet fission (SF) mechanism. The rate of singlet fission of polyacenes in the presence of QDs is a critical parameter in determining the performance of such devices. The present study demonstrates that the rates of SF in a pentacene derivative, 6,13-dipenylpentacene (DPP), are modulated by forming coaggregates with PbS QDs in aqueous dispersions. PbS QDs generally accelerate SF within DPP aggregates, and the extent of acceleration depends on the size of the QD. The average rate of SF increases from 0.074 ps-1 for DPP-only aggregates to 0.37 ps-1 within DPP-D co-aggregates for QDs with radius 2.2 nm, whereas co-aggregation with the smallest (r = 1.6 nm) and largest (r = 2.7 nm) QDs we tried only slightly change the SF rate. The rate variation is associated with (i) the density of surface ligands, which is influenced by the faceting of the PbS surface, and (ii) the local dielectric constant for the DPP. To accelerate SF, the ligands should be dense enough to provide sufficient affinity for DPP aggregates and effectively perturb the perpendicular alignment of DPP monomers within aggregates to increase the intermolecular coupling that promotes SF, but should not be too dense so as to form a low dielectric environment that disfavors SF. The study suggests that it is critical to consider the influence of the microenvironment of QD surface on photophysical processes when fabricating QD/organic hybrid devices.
关键词： pentacene,photovoltaic devices,PbS,quantum dots,singlet fission
更新于2025-09-11 14:15:04
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Pentacene Crystal Growth on Silica and Layer-Dependent Step-Edge Barrier From Atomistic Simulations
摘要： Understanding and controlling the growth of organic crystals deposited from the vapor phase is important for fundamental materials science and necessary for its application in pharmaceutical and organic electronics industries. Here this process is studied for the paradigmatic case of pentacene on silica by means of a specifically tailored computational approach inspired by the experimental vapor deposition process. This scheme is able to reproduce the early stages of the thin film formation, characterized by a quasi layer-by-layer growth, thus showcasing its potential as a tool complementary to experimental techniques for investigating organic crystals. Crystalline islands of standing molecules are formed at a critical coverage, as a result of a collective reorientation of disordered aggregates of flat-lying molecules. The growth then proceeds by sequential attachment of molecules at the cluster and then terrace edges. Free energy calculations allowed us to characterize the step edge barrier for descending the terraces, a fundamental parameter for growth models for which only indirect experimental measurements are available. The barrier is found to be layer dependent (approximately 1 kcal/mol for the first monolayer on silica, 2 kcal/mol for the second monolayer) and to extend over a distance comparable with the molecular length.
关键词： pentacene,atomistic simulations,silica,step-edge barrier,crystal growth
更新于2025-09-11 14:15:04
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Intermolecular Singlet Fission in Unsymmetrical Derivatives of Pentacene in Solution
摘要： Intermolecular singlet fission (SF) is an electronically coupled process between two chromophores, where distance dependences are decisive in terms of rates and yields. In the current work, a family of pentacene derivatives featuring different functional groups have been designed, synthesized, and probed with respect to intermolecular SF in the low, medium, and high concentration regimes rather than in the solid state. By means of advanced photophysical techniques, global analysis modeling, and ab initio calculations, a model for intermolecular SF is postulated. The model is based on an early key intermediate, which involves the diffusional encounter between one pentacene in its singlet excited-state with another one in its ground state and which features excimer characteristics. This is followed by a transformation into a coupled triplet excited-state. The role of the functional group appended to pentacene is analyzed with respect to steric shielding of the pentacene core as a means to prevent photophysical degradation, as well as control diffusional encounter and, subsequently, SF. The findings demonstrate the potential of new molecular materials for SF, especially in solution studies, as well as the challenges of implementing them in energy conversion schemes due to the appearance of photodegradation processes that compete with SF.
关键词： triplet diffusion,excitonic intermediates,singlet fission,unsymmetrical pentacene
更新于2025-09-10 09:29:36
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Synthesis, Structure, Photophysical Properties, and Photostability of Benzodipyrenes
摘要： We explored the syntheses, structure, photophysical properties, and photostability of benzodipyrenes (BDPs). BDPs were synthesized through an InCl3-AgNTf2 catalyzed, four-fold alkyne benzannulation reaction. The structures of BDP 4a and its corresponding endoperoxide product were unambiguously confirmed by X-ray crystallography. The BDPs reported here can also be recognized as peri- and cata-benzannulated pentacenes with a non-functionalized central ring. Unlike the previous reported pentacene-based polycyclic aromatic hydrocarbons, the absorbance of the BDPs was blue-shifted by ca. 40 nm relative to pentacene, even after extension of π–conjugation. The newly synthesized BDP products exhibit good relative stability with half-lives as high as 4612 min in THF.
关键词： pentacene,benzannulation,alkyne,singlet oxygen,photostability
更新于2025-09-10 09:29:36
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Tetra-Aza-Pentacenes via a One-Pot Friedl?nder Synthesis
摘要： Tetra-aza-pentacenes are attractive n-type small molecules for optoelectronic device applications, yet their syntheses are often laborious. Disclosed here is a one-pot Friedl?nder synthesis of 1,7,8,14-tetraazapentacece (tAP) derivatives (linear and/or bent), fully aromatized in-situ despite the absence of an exogenous oxidant. The photophysics of linear tAPs resembles that of regular pentacene while their crystal structures differ. A LUMO energy of -3.71 eV for di-tert-butylanisole-substituted linear tAP is similar to that of the well-known acceptor, C60.
关键词： one-pot synthesis,n-type molecules,tetra-aza-pentacene,Friedl?nder reaction,acenes
更新于2025-09-10 09:29:36
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Boosting Direct X-Ray Detection in Organic Thin Films by Small Molecules Tailoring
摘要： The attention focused on the application of organic electronics for the detection of ionizing radiation is rapidly growing among the international scientific community, due to the great potential of organic technology to enable large-area conformable sensor panels. However, high-energy photon absorption is challenging as organic materials are constituted of atoms with low atomic numbers. Here it is reported how, by synthesizing new solution-processable organic molecules derived from 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) and 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene, with Ge-substitution in place of the Si atoms to increase the material atomic number, it is possible to boost the X-ray detection performance of organic thin films on flexible plastic substrates. Bis(triisopropylgermylethynyl)-pentacene based flexible organic thin film transistors show high electrical performance with higher mobility (0.4 cm2 V?1 s?1) and enhanced X-ray sensitivity, up to 9.0 × 105 μC Gy?1 cm?3, with respect to TIPS-pentacene-based detectors. Moreover, similar results are obtained for 5,11-bis(triethylgermylethynyl)anthradithiophene devices, confirming that the proposed strategy, that is, increasing the atomic number of organic molecules by chemical tailoring to improve X-ray sensitivity, can be generalized to organic thin film detectors, combining high X-ray absorption, mechanical flexibility, and large-area processing.
关键词： organic X-ray detectors,thin film transistors,TIPS-pentacene,TIPGe-pentacene
更新于2025-09-09 09:28:46
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Dynamic Nuclear Polarization Using Photo-Excited Triplet Electron Spins in Eutectic Mixtures
摘要： Dynamic nuclear polarization using photo-excited triplet electrons (Triplet-DNP) is a method to significantly enhance nuclear spin polarization even in a low magnetic field and at room temperature. Pentacene has been practically used as an efficient polarizing agent for Triplet-DNP. In this study, we demonstrate room temperature 1H and 13C hyperpolarization of eutectic mixtures of deuterated benzoic acid doped with pentacene and a target molecule such as salicylic acid, nicotinic acid, or 2-naphthoic acid. These molecules are otherwise difficult to hyperpolarize by Triplet-DNP due to the low pentacene-dopabilities of these molecules. The highest 1H polarization of 1.2% has been obtained for the eutectic mixture of salicylic acid in 0.39 T. The present sample preparation is a crucial method to widen the range of applications of Triplet-DNP to chemical and biomedical analyses.
关键词： Pentacene,Eutectic mixtures,Hyperpolarization,Dynamic nuclear polarization,Triplet-DNP
更新于2025-09-09 09:28:46
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Nucleation of diindenoperylene and pentacene at thermal and hyperthermal incident kinetic energies
摘要： The authors have examined the nucleation of diindenoperylene (DIP) on SiO2 employing primarily atomic force microscopy and focusing on the effect of incident kinetic energy employing both thermal and supersonic sources. For all incident kinetic energies examined (Ei ? 0.09–11.3 eV), the nucleation of DIP is homogeneous and the dependence of the maximum island density on the growth rate is described by a power law. A critical nucleus of approximately two molecules is implicated by our data. A re-examination of the nucleation of pentacene on SiO2 gives the same major result that the maximum island density is determined by the growth rate, and it is independent of the incident kinetic energy. These observations are readily understood by factoring in the size of the critical nucleus in each case, and the island density, which indicates that diffusive transport of molecules to the growing islands dominate the dynamics of growth in the submonolayer regime.
关键词： thermal,SiO2,supersonic sources,diindenoperylene,hyperthermal,kinetic energies,nucleation,atomic force microscopy,pentacene
更新于2025-09-09 09:28:46