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Synergetic interface and morphology modification to achieve highly efficient solution-processed sky-blue organic light-emitting diodes
摘要： Solution-processed organic light-emitting diodes (OLEDs), especially blue OLEDs, generally suffer from the low efficiency. Herein, we report an efficient approach to achieve high efficiency by synergetic interface and morphology modification with a polymer, Poly(9-vinylcarbazole) (PVK). Sky-blue thermally activated delayed fluorescent (TADF) material, 10-(4-(4,6-diphenyl-1,3,5- triazin-2-yl)phenyl)-10H- spiro[acridine-9,9-fluorene] (SpiroAC-TRZ), is used as the emitter. The incorporation of PVK thin layer at the hole injection layer/emission layer (EML) interface and a small amount of PVK inner the EML modify the carrier behaviors at the interface and improve the EML morphology. As a result, balanced carrier distribution and reduced carrier recombination are realized at the interface and inner the EML. Through these strategies, the maximum external quantum efficiency and current efficiency of the optimal OLED achieve 25.1% and 53.5 cd/A. To the best of our knowledge, the efficiencies are the highest values ever achieved by the solution-processed sky-blue TADF OLEDs.
关键词： Blue organic light-emitting diodes,Thermally activated delayed fluorescence,High efficiency,All-solution process,Film morphology
更新于2025-09-23 15:21:01
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Influence of Film Morphology on Transient Photocurrent Pulse Shape in Organic Thin Films: A Monte Carlo Study
摘要： The in?uence of ?lm morphology on the broadening of the time-of-?ight transient photo-current pulse is investigated using Monte Carlo simulation. Simulation of the time-of-?ight transient photo-current pulse shape is carried out for homogeneous and inhomogeneous organic thin ?lms by varying the overall energetic disorder. In homogeneous system, the value of the tail broadening parameter (W) of the photocurrent pulse is found to decrease upon decreasing the energetic disorder, which can be attributed to the variation in the non-thermal ?eld assisted diffusion. Interestingly, in the case of inhomogeneous system, upon decreasing the overall energetic disorder of the system the value of W initially attains a maximum value before it starts decreasing. This observation is explained in terms of the morphology dependent carrier diffusion. This study asserts the importance of the in?uence of the morphology dependent carrier diffusion on the charge transport in disordered systems and the related experimental measurements.
关键词： Polycrystalline organic thin ?lms,Charge transport,Tail broadening,Diffusion,Time of ?ight photoconductivity,Film Morphology
更新于2025-09-23 15:21:01
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Additivea??Assisted Hota??Casting Free Fabrication of Diona??Jacobson 2D Perovskite Solar Cell with Efficiency Beyond 16%
摘要： Two-dimensional (2D) Dion-Jacobson (DJ) perovskite solar cells (PVSCs) with high power conversion efficiency (PCE) are currently predominately fabricated via a hot-casting process. The reason lies in the difficulty in preparing high-quality perovskite film under mild condition when the application of divalent ammonium removes the weak interaction from the spacer cation layer. In this work, the morphology of the 2D DJ perovskite film with rigid piperidinium ring is tuned through room-temperature spin-coating method, with the aid of methylammonium thiocyanate (MASCN) additive. With optimized amount of MASCN addition, the perovskite films deposited on poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA)/poly[(9,9-bis(30-(N,N-dimethylamino)propyl)-2,7-uorene)-alt-2,7-(9,9-dioctylfuorene)] (PFN) substrate exhibit fine crystallinity, preferred orientation, decreased defects and better energy level alignment with the hole transport layer. The device with inverted planar structure presents JSC of 17.91 mA cm-2, VOC of 1.19 V, FF of 0.76, with a maximum PCE of 16.25%, which is the highest PCE for 2D DJ PVSCs free of hot-casting. The unsealed device maintained around 80% of its initial efficiency after 35 days exposure to air (Hr = 45 ± 5%). This work provides a potential route towards high performance 2D DJ PVSCs.
关键词： additive,2D perovskite,film morphology,charge transport,growth orientation
更新于2025-09-23 15:19:57
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Tetraphenylbutadiene-Based Symmetric 3D Hole-Transporting Materials for Perovskite Solar Cells: A Trial Trade-off between Charge Mobility and Film Morphology
摘要： Two three-dimensional symmetric tetraphenylbutadiene derivatives decorated with diphenylamine or triphenylamine fragments are first prepared for use as hole-transporting materials (HTMs) in perovskite solar cells (PSCs). The HTMs are acquired using straightforward synthetic methods and facile purification techniques. The thermal stability, photophysical properties, electrochemical behaviors, computational study, hole mobility, X-ray diffraction, hole transfer dynamics, hydrophobicity, surface morphology, and photovoltaic performances of the HTMs are discussed. The highest power conversion efficiency (PCE) of CJ-04-based cell is 13.75%, which is increased to 20.06% when CJ-03 is used as HTM, superior to the PCE of the cell based on 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) (18.90%). The preparation cost of CJ-03 accounts for merely 23.1% of the price of commercial spiro-OMeTAD, while the concentration of CJ-03 solution used in the device fabrication (60.0 mg mL–1) is lower compared with that of the spiro-OMeTAD solution (72.3 mg mL–1). These results corroborate that the screw-like HTMs with a highly distorted configuration are facilely available and promising candidates for PSCs. More importantly, a practical solution is proposed to achieve moderate charge mobility and good film-formation ability of the HTMs simultaneously.
关键词： butadiene,hole-transporting materials,film morphology,charge transport,perovskite solar cells
更新于2025-09-19 17:13:59
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Two-dimensional Ruddlesdena??Popper layered perovskite for light-emitting diodes
摘要： Solution-processed metal halide perovskite light-emitting diodes (PeLEDs) have attracted extensive attention due to the great potential application in energy-efficient lighting and displays. Two-dimensional Ruddlesden–Popper (2DRP) layered perovskites exhibit high photoluminescence quantum efficiency, improved film morphology, and enhanced operational stability over their three-dimensional counterparts, making them attractive for high-performance PeLEDs. In addition, 2DRP perovskite materials with a tunable exciton binding energy are suitable for preparing PeLEDs with color-tunability. In this perspective, we first introduce the merits of the 2DRP layered perovskites in terms of their structural characteristics. The progress in 2DRP PeLEDs is then reviewed. The challenges and new opportunities of the PeLEDs are finally discussed. We hope to open up new perspectives for rational designs of the 2DRP perovskite materials for PeLEDs with unprecedented efficiency and stability.
关键词： operational stability,film morphology,photoluminescence quantum efficiency,Two-dimensional Ruddlesden–Popper layered perovskite,color-tunability,light-emitting diodes
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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A pre-solution mixing precursor method for improving the crystallization quality of perovskite films and electroluminescence performance of perovskite light-emitting diodes
摘要： Quasi-two-dimensional (Q-2D) perovskites are one kind of efficient luminescent material with fast energy transfer and radiative decay of excitons due to the energy cascade formed by the mixed perovskite phase. However, the existence of monolayer or bilayer nanosheets in the Q-2D perovskite film results in poor charge transport, high trap density and rough film surface because of the high ratio of ligands, which leads to poor performance of Q-2D perovskite light-emitting diodes (PeLEDs). Herein, we proposed a new strategy of a pre-solution mixing (PSM) precursor to inhibit the formation of ultrathin perovskite nanosheets, which significantly enhanced the charge carrier mobility, reduced the concentration of defects and improved the film morphology. The PeLEDs based on the PSM precursor achieved the maximum luminescence of 7832.1 cd m?2 (～218% enhancement) and the peak current efficiency of 6.0 cd A?1 (～131% enhancement). By introducing mixed cations in the PeLED, the maximum brightness of 14 211.0 cd m?2 and current efficiency of 14.6 cd A?1 were realized, demonstrating the generality of our PSM method for the preparation of high performance PeLEDs.
关键词： charge transport,pre-solution mixing,Quasi-two-dimensional perovskites,film morphology,light-emitting diodes
更新于2025-09-16 10:30:52
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Engineering Charge-Transfer States for Efficient, Low-Energy-Loss Organic Photovoltaics
摘要： Charge transfer (CT) between donors and acceptors following photoexcitation of organic photovoltaics (OPVs) gives rise to bound electron–hole pairs across the donor–acceptor interface, known as CT states. While these states are essential to charge separation, they are also a source of energy loss. As a result of reduced overlap between electron and hole wavefunctions, CT states are influenced by details of the film morphology and molecular structure. Here, we describe several important strategies for tuning the energy level and dynamics of the CT state and approaches that can enhance their dissociation efficiency into free charges. Furthermore, we provide an overview of recent physical insights into the key parameters that significantly reduce the Frenkel-to-CT energy offset and recombination energy losses while preserving a high charge-generation yield. Our analysis leads to critical morphological and molecular design strategies for achieving efficient, low-energy-loss OPVs.
关键词： molecular structure,energy loss,organic photovoltaics,charge transfer states,film morphology
更新于2025-09-12 10:27:22
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Surpassing the 10% efficiency milestone for 1-cm2 all-polymer solar cells
摘要： Naphthalenediimide-based n-type polymeric semiconductors are extensively used for constructing high-performance all-polymer solar cells (all-PSCs). For such all-polymer systems, charge recombination can be reduced by using thinner active layers, yet suffering insufficient near-infrared light harvesting from the polymeric acceptor. Conversely, increasing the layer thickness overcomes the light harvesting issue, but at the cost of severe charge recombination effects. Here we demonstrate that to manage light propagation within all-PSCs, a thick bulk-heterojunction film of approximately 350 nm is needed to effectively enhance photo-harvesting in the near-infrared region. To overcome the severe charge recombination in such a thick film, a non-halogenic additive is used to induce a well-ordered micro-structure that inherently suppresses recombination loss. The combined strategies of light management and delicate morphology optimization lead to a promising efficiency over 10% for thick-film all-PSCs with active area of 1 cm2, showing great promise for future large-scale production and application of all-PSCs.
关键词： all-polymer solar cells,light management,naphthalenediimide,thick-film,morphology optimization
更新于2025-09-11 14:15:04
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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