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Null Exciton Splitting in Chromophoric Greek Cross?(+) Aggregate
摘要： Exciton interactions in molecular aggregates play a crucial role in tailoring the optical behaviour of p-conjugated materials. Though vital for optoelectronic applications, ideal Greek cross-dipole (a = 908) stacking of chromophores remains elusive. We report a novel Greek cross (+) assembly of 1,7-dibromoperylene-3,4,9,10-tetracarboxylic tetrabutylester (PTE-Br2) which exhibits null exciton coupling mediated monomer-like optical characteristics in the crystalline state. In contrast, nonzero exciton coupling in X-type (a = 70.28, PTE-Br0) and J-type (a = 08, q = 48.48, PTE-Br4) assemblies have perturbed optical properties. Additionally, the semi-classical Marcus theory of charge-transfer rates predicts a selective hole transport phenomenon in the orthogonally stacked PTE-Br2. Precise rotation angle dependent optoelectronic properties in crystalline PTE-Br2 can have consequences in the rational design of novel p-conjugated materials for photonic and molecular electronic applications.
关键词： crystal engineering,chromophore aggregate,fluorescence,charge mobility,exciton splitting
更新于2025-09-23 15:21:01
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The effects of layer thickness and charge mobility on performance of FAI:MABr:PbI <sub/>2</sub> :PbBr <sub/>2</sub> perovskite solar cells: GPVDM simulation approach
摘要： The perovskite solar cells (PSCs) have been extensively interested and its performance has rapidly increased up to 24.2 %. Layer thickness and charge mobility are crucial for high-performance perovskite solar cells. In this paper, we study the effect of layer thickness and charge mobilities on some parameters in perovskite solar cell based on structure of FTO/TiOx/SnO2/FAIMABrPbI2PbBr2/Spiro-OMeTAD/Ag by using the GPVDM (General- purpose Photovoltaic Device Model) software. The simulation results show that the best optimized power conversion efficiency of 23.88 % can be obtained. The optimal layer thickness in the simulation of TiOx, SnO2, FAIMABrPbI2PbBr2, Spiro-OMeTAD are 50 nm, 30 nm, 400 nm, 30 nm, respectively. The optimal electron and hole mobilities of photoactive layer are 2?10-5 m2V-1s-1and 2?10-6 m2V-1s-1, respectively. Comparative study of simulation and experiment are observed, that performance of 15.93 % of efficiency can be experimentally achieved, however the model of this solar cell is observed 18.43 % of efficiency by simulation.
关键词： layer thickness,GPVDM simulation,perovskite solar cells,power conversion efficiency,charge mobility
更新于2025-09-12 10:27:22
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Improved charge transfer, mobility and morphology for high performance panchromatic organic photodetectors by adding PC71BM in P3HT:IEICO-4F
摘要： High performance of panchromatic organic photodetectors (OPDs) with a wide spectral response ranged from 300 to 1000 nm were realized through adding [6,6]-phenyl-C71-butyric acid methylester (PC71BM) fullerene as an electron acceptor into the polymer donor of poly (3-hexylthiophene) (P3HT) and the small molecular non-fullerene acceptor of 2, 2′-((2Z,2′Z)-(((4, 4, 9, 9-tetrakis(4-hexylphenyl)-4, 9-dihydro-sindaceno[1, 2-b:5, 6-b′] dithiophene-2, 7-diyl)bis(4-((2-ethylhexyl)oxy)thiophene-5, 2-diyl))bis-(methanylylidene))bis(5, 6-di?uoro-3-oxo-2, 3-dihydro-1H-indene-2, 1-diylidene))dimalononitrile (IEICO-4F) host system. The fabricated OPD exhibited a high detectivity (D*) of 1.35 × 1012 Jones at 805 nm by adding 10 wt% PC71BM, which is 1.5 folds higher than it from the control system. The improved performance was mainly attributed to the increased light absorption in the short wavelength range and cascade energy level alignment, which is responsible for the e?cient light harvesting and exciton utilization. Furthermore, the active layer morphology was optimized by adjusting the ratio of PC71BM acceptor, which e?ciently enhances charge transport and mobility of the device as well as suppress bimolecular recombination. This work indicates that adding fullerene into non-fullerene system plays a positive e?ect on the device performance of panchromatic OPDs.
关键词： Film morphology,Charge mobility,Non-fullerene and fullerene acceptors,Panchromatic organic photodetector,Charge transfer
更新于2025-09-11 14:15:04
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Solution-Processable All-Small-Molecule for High-Performance Nonfullerene Organic Solar Cells with High Crystallinity Acceptor
摘要： In this work, two small molecule acceptors (IDIC and IDIC-4F) with different crystallinity and energy level have been successfully applied in nonfullerene-based all-small molecule organic solar cells (NFASM-OSCs). The donor of DFDT(DPP)2 was chosen because of complementary absorption with IDIC and IDIC-4F. As acceptor, IDIC-4F exhibited a higher PCE than IDIC due to better crystallinity. This work not only shows us how to balance the relationship between Voc and Jsc, but also suggests us how to get a good phase separation morphology. Moreover, Increased crystallinity helps to inhibit bimolecular recombination and increase charge mobility. By optimizing device preparation conditions, the best PCE of 9.43% for DFDT(DPP)2 : IDIC-4F as active layer was achieved with excitable Jsc (16.83 mA cm-2) and FF (0.65). The FF and Jsc of resultant device show a significant increased which is among the top efficiencies based on DPP as terminal acceptor groups of NFSM-OSCs reported in document up to now.
关键词： crystallinity,small molecule acceptors,phase separation morphology,nonfullerene organic solar cells,charge mobility
更新于2025-09-11 14:15:04
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Light-Tuned DC Conductance of Anatase TiO2 Nanotubular Arrays: Features of Long-Range Charge Transport
摘要： Experimental results related to the photoactivated dc conductance of anatase TiO2 nanotubular arrays (aTNTAs) under pulsed irradiation by a laser light inside and outside the fundamental absorption band are presented. It is found that the mobility and diffusion coefficients of charge carriers in the examined aTNTA are extremely low due to a strong charge-phonon coupling, abundance of shallow traps, and hopping conductivity between adjacent nanotubes. We consider that the confining electric field appeared within the array structure due to the difference in the local concentrations of excess electrons and holes at large values of the dc conductance suppresses the drift current. In this case, the dc conductance of such aTNTAs is mainly matured by the diffusion of mobile carriers. A recurrent kinetic model for evolution of the dc conductance of aTNTAs under laser irradiation has been proposed to interpret the experimental results.
关键词： anatase nanotubes,laser irradiation,dc conductance,Urbach energy,drift current,inter-band transition,diffusion current,charge mobility
更新于2025-09-10 09:29:36
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Charge Mobility and Recombination Mechanisms in Tellurium van der Waals Solid
摘要： Trigonal tellurium is a small band gap elemental semiconductor consisting of van der Waals bound one-dimensional helical chains of tellurium atoms. We study the temperature dependence of the charge carrier mobility and recombination pathways in bulk tellurium. Electrons and holes are generated by irradiation of the sample with 3 MeV electrons and detected by time-resolved microwave conductivity measurements. A theoretical model is used to explain the experimental observations for different charge densities and temperatures. Our analysis reveals a high room temperature mobility of cm2V-1s-1. The mobility is thermally deactivated suggesting a band-like transport mechanism. According to our analysis charges predominantly recombine via radiative recombination with a radiative yield close to 98%, even at room temperature. The remaining charges recombine by either trap-assisted (Shockley-Read-Hall) recombination or undergo trapping to deep traps. The high mobility, near unity radiative yield and the possibility of large-scale production of atomic wires by liquid exfoliation make Te of high potential for next-generation nanoelectronic and optoelectronic applications, including far-infrared detectors and lasers.
关键词： recombination mechanisms,charge mobility,optoelectronic applications,Tellurium,van der Waals solid
更新于2025-09-04 15:30:14
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Board‐like Fused‐Thiophene Liquid Crystals and Their Benzene Analogues: Facile Synthesis, Self‐assembly, p‐Type Semiconductivity, and Photoluminescence
摘要： Novel fused-thiophene discotic liquid crystals were designed and easily synthesized by Suzuki coupling and FeCl3 oxidized tandem cyclo-dehydrogenation reactions, including homo- and cross-coupling reactions. The resulting hexagonal and rectangular columnar mesomorphic supramolecular structures formed were characterized by polarizing optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering. Charge carrier transport properties in the mesophases of two of the synthesized fused-thiophene discogens were measured by transient photocurrent time-of-flight (TOF) technique, revealing fast hole transport values in the range of 10-3 to 10-2 cm2 V-1s-1, thus demonstrating potential applications in electronic devices. The luminescent sanidic mesogens, having different extended π-conjugated systems, also emit blue, green or red light, with absolute photoluminescent quantum yields as high as 18%.
关键词： thiophene,luminescence,mesophase,cyclo-hydrogenation,charge mobility
更新于2025-09-04 15:30:14
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Impact of Low‐Frequency Vibrations on Charge Transport in High‐Mobility Organic Semiconductors
摘要： Despite decades of intensive studies of charge transport in organic semiconductors (OSs), understanding of mechanisms underpinning efficient charge transport in them remains elusive. Recently, it has been suggested that low-frequency (LF) vibrations are a limiting factor of charge transport in high-mobility OSs. Nevertheless, the relationship between the molecular structure, crystal packing, LF vibrations, and charge transport is still obscured. This hinders the focused search of high-mobility OSs so that researchers rely mainly on trial-and-error method. This review presents theoretical and experimental approaches to studying the LF vibrations and their role in charge transport with a focus on recent results. It is anticipated that tight cooperation between experimentalists and theorists will yield an advanced understanding of LF vibrations in OSs and their impact on charge transport. This will guide the design of novel high-mobility organic semiconductors for organic electronics.
关键词： structure–property relationship,organic electronics,Raman spectroscopy,electron–phonon interaction,charge mobility
更新于2025-09-04 15:30:14