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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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Enhancing charge mobilities in self-assembled Na?ˉI halogen bonded organic semiconductors: A design approach based on experimental and computational perspectives
摘要： Charge transport in pyridine-ethynyliodophenyl supramolecules that involve intermolecular halogen bonding is studied by a combined experimental and computational approach. Selective fluorination of the molecules determines their crystallization pattern and is found to potentially increase the charge mobilities in the crystal. We report the synthesis of the molecules, full chemical characterization and resolved crystal structures. Computational analysis of the charge transport is provided to understand at the molecular level the structure-function relationships determining the charge mobilities. Combination of selective fluorination, halogen bonding motif and increased π system is highlighted as bearing the potential to achieve both enhanced hole and electron mobilities.
关键词： Selective fluorination and phenylation,Hole and electron mobility,Halogen bonding,Organic semiconductors,Charge transport,Density functional theory
更新于2025-09-16 10:30:52
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Combining steady-state with frequency and time domain data to quantitatively analyze charge transport in organic light-emitting diodes
摘要： Typically, organic light-emitting diodes (OLEDs) are characterized only in steady-state to determine and optimize their efficiency. Adding further electro-optical measurement techniques in frequency and time domain helps to analyze charge carrier and exciton dynamics and provides deeper insights into the device physics. We, therefore, first present an overview of frequently used OLED measurement techniques and analytical models. A multilayer OLED with a sky-blue thermally activated delayed fluorescent dopant material is employed in this study without loss of generality. Combining the measurements with a full device simulation allows one to determine specific material parameters such as the charge carrier mobilities of all the layers. The main part of this tutorial focuses on how to systematically fit the measured OLED characteristics with microscopic device simulations based on a charge drift-diffusion and exciton migration model in 1D. Finally, we analyze the correlation and sensitivity of the determined material parameters and use the obtained device model to understand limitations of the specific OLED device.
关键词： charge transport,frequency domain,OLED,time domain,material parameters,device simulation
更新于2025-09-16 10:30:52
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Size Effect of Two Dimension Conjugated Space in Photovoltaic Polymersa?? Side-chain: Balancing Phase Separation and Charge Transport
摘要： Various two-dimension (2D) side-chains substituted benzo(1,2-b:4,5-b’)dithiophene (BDT) blocks have been used to construct donor polymers, while the size effect of side-chains on photovoltaic performance was overlooked in past few years. This work, three size varied conjugated space (benzene, naphthalene and biphenyl) were introduced into corresponding polymers PBDB-Ph, PBDB-Na and PBDB-BPh. This space engineering has significant impact on the extent of phase separation in active layer which blended with polymer and acceptor ITCPTC and preserved the desired morphology. Varied space size in side-chains lead to distinct balance mobility ratios of hole to electron (benzene is 0.21, and for naphthalene is 0.75, biphenyl is 0.57). Finally, PBDB-Na-based polymer solar cells (PSCs) delivered the highest power conversion efficiency (PCE) 12.52% when compared to the PSCs performance of PBDB-Ph (8.48%) and PBDB-BPh (11.35%). The mothed in tailoring the side-chains structures could fabricate a balance between phase separation and charge transport, providing an enlightenment for the development of photovoltaic device.
关键词： side-chain,phase separation,desired morphology,charge transport,photovoltaic performance
更新于2025-09-16 10:30:52
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Hysteresis-free Planar Perovskite Solar Cells with a Breakthrough Efficiency of 22% and Superior Operational Stability over 2000 Hours
摘要： Understanding the transport loss and the ways to improving opto-electronic properties of the charge transporting layers is critical to fabricate highly efficient, long-term stable, and hysteresis-free perovskite solar cells (PSCs). Herein, we report success in suppressing hysteresis and boosting the performance of operationally stable planar solar cells using ruthenium (Ru) doped tin oxide (SnO2) electron transport layer (ETL) and Zn-TFSI2 doped spiro-OMeTAD hole transport layer (HTL). Apparently, the incorporation of Ru drastically shifted the Fermi level of SnO2 ETL upward, which provides a facile route to tailor the ETL/perovskite band-offset to improve built-in electric field of devices for improving VOC and electron extraction, simultaneously. Meanwhile, rapid injection of the photo-generated electrons from perovskite into ETL with reduced trap density is also observed when Ru doped SnO2 is employed as ETL. On the other hand, the conception of Zn-TFSI2 incorporation into HTL not only further boost the photovoltaic performance but also prolong the photo-stability of the devices. Consequently, a breakthrough efficiency of 22% (average 21.8%) with JSC of 24.6 mA cm?2, VOC of 1.15 V and FF of 0.78 has been obtained in planar-type PSCs with a loss in efficiency of only ~3% at maximum power point tracking (MPPT) over 2000?h.
关键词： Ruthenium doping,Charge transport layer,SnO2,Zn-TFSI2,Stability
更新于2025-09-16 10:30:52
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Hybrid CdSe/CsPbI <sub/>3</sub> quantum dots for interface engineering in perovskite solar cells
摘要： Hybrid CdSe/CsPbI3 quantum dots (QDs) are selected for incorporation between the perovskite film and the hole transport layer (HTL). Owing to the high absorption coefficient and the suitable band gap of CsPbI3, an optimized energy level structure can be expected. Besides, energy transfer could be realized due to the overlap between the emission spectrum of CdSe QDs and the excitation spectrum of CsPbI3 QDs. Hence, CdSe/CsPbI3 QDs can serve as an interface layer to promote interfacial charge extraction and enhance light harvesting ability simultaneously. Compared with pristine perovskite solar cells (PSCs), hybrid CdSe/CsPbI3 QD incorporated PSCs achieve 21% enhancement in power conversion efficiency (PCE). The enhancement of PCE can be ascribed to the ultrafast charge carrier dynamics and F?rster resonance energy transfer (FRET) effect. The design of hybrid CdSe/CsPbI3 QDs offers an alternative method for interfacial engineering to enhance optical properties and facilitate the charge transport process in PSCs.
关键词： interface engineering,charge transport,perovskite solar cells,Hybrid CdSe/CsPbI3 quantum dots,F?rster resonance energy transfer
更新于2025-09-16 10:30:52
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Fabrication and performance of AC-coupled LGADs
摘要： Detectors that can simultaneously provide ?ne time and spatial resolution have attracted wide-spread interest for applications in several ?elds such as high-energy and nuclear physics as well as in low-energy electron detection, photon science, photonics and imaging. Low-Gain Avalanche Diodes (LGADs), being fabricated on thin silicon substrates and featuring a charge gain of up to 100, exhibit excellent timing performance. Since pads much larger than the substrate thickness are necessary to achieve a spatially uniform multiplication, a ?ne pad pixelation is di?cult. To overcome this limitation, the AC-coupled LGAD approach was introduced. In this type of device, metal electrodes are placed over an insulator at a ?ne pitch, and signals are capacitively induced on these electrodes. At Brookhaven National Laboratory, we have designed and fabricated prototypes of AC-coupled LGAD sensors. The performance of small test structures with di?erent particle beams from radioactive sources are shown.
关键词： Charge transport and multiplication in solid media,Detector modelling and simulations II (electric ?elds, charge transport, multiplication and induction, pulse formation, electron emission, etc),Solid state detectors,Timing detectors
更新于2025-09-12 10:27:22
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Highly Crystallized C-Doped Nickel Oxide Nanoparticles for p-Type Dye-Sensitized Solar Cells with Record Open-Circuit Voltage Breaking 0.5 V
摘要： In this work, unique carbon-doped NiO nanostructure (denoted as C/NiO) was synthesized via a facile precipitation/reduction reaction, followed by a subsequent oxidation process. The successful introduction of carbon in NiO gave rise to multiple tailing of the physical and electronic characteristics, including morphology, crystallinity, and conductivity, and valence band edge position. The carbon-doped NiO-fabricated dye sensitized solar cells actively generated an unrivalled VOC of 0.50 V and also a significantly increased short-circuit current densities (JSC, 0.202 mA cm-2), leading to an overall efficiency of 0.053%. The improved of photovoltaic performance could be mainly attributed to the significantly enhanced charge transport property and regarded charge recombination occurred at the NiO/electrolyte interface. This work provides an extremely simple and effective strategy for incorporating nonmetal elements in semiconductor oxides with remarkably improved photovoltaic performance.
关键词： charge transport,carbon-doped NiO,dye-sensitized solar cells,photovoltaic performance,valence band edge
更新于2025-09-12 10:27:22
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Highly oriented perovskites for efficient light-emitting diodes with balanced charge transport
摘要： Ruddlesden-Popper (RP) perovskites have attracted interests due to high performance in perovskite light-emitting diodes (PeLEDs). However, the insulating organic spacers decrease carrier mobility, and increase charge accumulation and non-radiative recombination losses, which significantly undermine device performance. Herein, by blending NH3I(CH2)8NH3I (ODA) and INH3(CH2)2O(CH2)2O(CH2)2NH3I (EDBE) large organic spacers into the precursor solution, we achieve preferential orientation of perovskite crystals perpendicular to the substrate with conductive channels across the two injecting electrodes. Consequently, effective charge injection and balanced charge transport are achieved, which is beneficial to increase radiation recombination. A low turn-on voltage of 1.4 V is achieved for mixture-1.5 perovskite (ODA: EDBE=3:2, molar ratio) PeLEDs, and a maximum external quantum efficiency increases to 5.8% (EL peak ≈766 nm) at 2.0 V with a current density of 6.05 mA cm?2 compared to that of the pure ODA (2.4%) and EDBE (1.1%) devices. The findings may spur new developments in charge injection and electron-hole balance for realizing efficient PeLEDs.
关键词： Perovskites,Ruddlesden-Popper,Organic spacers,Light-emitting diodes,Charge transport
更新于2025-09-12 10:27:22
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Naphthalene core-based noncovalently fused-ring electron acceptors: effects of linkage positions on photovoltaic performances
摘要： Two mutually isomeric noncovalently fused-ring electron acceptors (NC-FREAs) NOC6F-1 and NOC6F-2 containing two cyclopentadithiophene (CPDT) moieties linked at the 2,6- and 1,5-positions, respectively, of the naphthalene ring were designed and synthesized for organic solar cells (OSCs). Intramolecular noncovalent S···O interactions were introduced into NOC6F-1 and NOC6F-2. The tiny structural variation in NOC6F-1 and NOC6F-2 by just changing the linkage positions affects largely their molecular configuration, absorption, molecular packing, charge transport and photovoltaic performance. Compared to NOC6F-2, NOC6F-1 exhibits smaller distortions between cyclopentadithiophene and the naphthalene unit, leading to an extended conjugation and enhanced p–p stacking. NOC6F-2 exhibits a poor planarity, which restricts the electron delocalization as well as dense p–p stacking in the film form. When blended with PBDB-T, NOC6F-1 exhibits more orderly stacking along both the out-of-plane and in-plane directions than NOC6F-2. OSCs based on PBDB-T:NOC6F-2 merely showed a power conversion efficiency (PCE) of 6.74% with lower Jsc and FF values. OSCs based on NOC6F-1 achieved a higher Jsc of 17.08 mA cm?2 and an FF of 65.79%, thus leading to a significantly enhanced PCE of 10.62%. These results indicate that use of the acceptor molecules with a planar molecular backbone is an important design strategy for NC-FREAs.
关键词： noncovalently fused-ring electron acceptors,charge transport,organic solar cells,photovoltaic performance,molecular configuration
更新于2025-09-12 10:27:22