- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Enhancing Photocarrier Bulk Lifetime with Defect Engineering of Polycrystalline Passivated-Contact n-Cz Photovoltaic Devices
摘要： We study the photocarrier lifetime evolution of n-Cz Si material throughout the processing sequence for polycrystalline passivated contact devices. We show that a high temperature annealing pretreatment (known as Tabula Rasa) has a clear effect on enhancing bulk lifetimes of n-Cz Si. We further this development by integrating such defect engineering into the lower-temperature annealing of passivated contact. By applying oxidizing ambient gases during these anneals we report a photocarrier lifetime enhancement over an N2 environment. This enhancement is exhibited in a 1-sun iVOC of 735 mV when annealed in O2 rather than 708 mV in N2.
关键词： monocrystalline silicon,intrinsic point defects,passivation,thermal processing,Czochralski,photocarrier lifetime
更新于2025-09-23 15:21:01
-
Rigid Oxygen-Bridged Boron-Based Blue Thermally Activated Delayed Fluorescence Emitter for Organic Light-Emitting Diode: Approach towards Satisfying High Efficiency and Long Lifetime Together
摘要： Thermally activated delayed fluorescence (TADF) materials have emerged as an efficient emitter for achieving high efficiency of blue organic light emitting diodes (OLEDs). However, it is challenging to satisfy both high device efficiency and long operational lifetime together. Here, highly efficient and electrochemically stable blue TADF emitter, 5-(5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)-10,15-diphenyl-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazole (DBA-DI) is designed and synthesized for high efficiency and long lifetime OLED. This emitter exhibits high photoluminescence quantum yield of 95.3%, small single-triplet energy gap of 0.03 eV, short delayed exciton lifetime of 1.25 μs, and high bond dissociation energy (BDE). Also, phosphine oxide free high triplet energy host systems (single and mixed) and exciton blocking layer materials are analyzed using molecular and optical simulations to find an efficient host system with high BDE and suitable emission zone for high efficiency and stable OLEDs. The fabricated OLED with DBA-DI and high triplet host exhibited a maximum external quantum efficiency (EQE) of 28.1% with blue CIE color coordinates of (0.16, 0.39) and long operational lifetime (LT50) of 329 h at the initial luminance of 1000 cd m?2. Furthermore, the mixed host-based TADF device showed a slightly lower EQE of 26.4% and almost two times longer lifetime (LT50: 540 h) than the single host device.
关键词： stable emitters,organic light emitting diodes,thermally activated delayed fluorescence,long lifetime
更新于2025-09-23 15:21:01
-
High efficiency and stability of ink-jet printed quantum dot light emitting diodes
摘要： The low efficiency and fast degradation of devices from ink-jet printing process hinders the application of quantum dot light emitting diodes on next generation displays. Passivating the trap states caused by both anion and cation under-coordinated sites on the quantum dot surface with proper ligands for ink-jet printing processing reminds a problem. Here we show, by adapting the idea of dual ionic passivation of quantum dots, ink-jet printed quantum dot light emitting diodes with an external quantum efficiency over 16% and half lifetime of more than 1,721,000 hours were reported for the first time. The liquid phase exchange of ligands fulfills the requirements of ink-jet printing processing for possible mass production. And the performance from ink-jet printed quantum dot light emitting diodes truly opens the gate of quantum dot light emitting diode application for industry.
关键词： quantum dot light emitting diodes,ink-jet printing,external quantum efficiency,dual ionic passivation,lifetime
更新于2025-09-23 15:21:01
-
High efficiency???low efficiency roll-off and long lifetime fluorescent white organic light-emitting diodes based on strategic management of triplet excitons via triplet-triplet annihilation up-conversion and phosphor sensitization
摘要： The simultaneous realization of high efficiency, low efficiency roll-off, long lifetime and stable electroluminescence (EL) spectra in fluorescent white organic light-emitting diodes (WOLEDs) is still a huge challenge. Here, we used a triplet-triplet annihilation up-conversion (TTA-UC) material as blue emission layer and phosphor sensitized fluorescent emitter as red emission layer and introduced a bipolar interlayer between them to fabricate high efficiency, low efficiency roll-off and long lifetime fluorescent WOLEDs. It is clearly seen that the bipolar interlayer not only efficiently distributed the singlet and triplet excitons, but also significantly stabilized the EL spectra. Thus, the resulting two-color fluorescent WOLEDs exhibited the maximum current efficiency (CE), power efficiency (PE) and external quantum efficiency (EQE) of 26.9 cd A-1, 22.3 lm W-1 and 12.8%, and remained 25.9 cd A-1, 16.9 lm W-1 and 12.1% at the luminance of 1000 cd m-2 and 23.1 cd A-1, 10.6 lm W-1 and 10.7% at the luminance of 10000 cd m-2, respectively, and the operational lifetime LT50 (50% decay, initial luminance of 1000 cd m-2) was also up to 984 h. It can be seen that these devices also showed stable EL spectra with Commission Internationale de I’Eclairage (CIE) of (0.51, 0.41) from 1000 cd m-2 to 5000 cd m-2 luminance. Furthermore, the fabricated three-color fluorescent WOLEDs by further introducing a green fluorescent emitter, also showed high efficiencies of 15.5 cd A-1, 13.0 lm W-1 and 8.1% and stable EL spectra with CIE of (0.43, 0.36) form 1000 cd m-2 to 5000 cd m-2 luminance. More importantly, their CE and EQE exhibited an increasing tendency with the luminance, a fully negligible efficiency roll-off. This design strategy provides a potential route towards high performance fluorescent WOLEDs.
关键词： fluorescent WOLEDs,bipolar interlayer,high efficiency,triplet-triplet annihilation up-conversion,phosphor sensitization,long lifetime,low efficiency roll-off
更新于2025-09-23 15:21:01
-
On the imprecisions that may be induced when applying the Blaugrund approximation for the analysis of Doppler-shift attenuation lifetime measurements
摘要： It is shown that the Blaugrund approximation could have led to some imprecise lifetime determinations in the past which used the Doppler-shift attenuation method (DSAM). Comparison with Monte Carlo simulations of the slowing-down process show that there is not an easy way to judge using them on the reliability of old data.
关键词： Lineshapes analysis in DSAM measurements,Monte Carlo simulations,Lifetime determination,Blaugrund approximation
更新于2025-09-23 15:21:01
-
Highly efficient charge generation and injection in HAT-CN/TAPC heterojunction for high efficiency tandem organic light-emitting diodes
摘要： An organic heterojunction (OHJ) consisted of 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN)/1,1-bis[(di-4-tolyamino)phenyl)]cyclohexane (TAPC) is employed simultaneously as both charge generation layer (CGL) and charge injectors to fabricate high efficiency and long lifetime tandem organic light-emitting diodes (OLEDs). It can be seen that compared with conventional tandem OLEDs, the tandem OLEDs utilizing OHJ as both CGL and charge injectors significantly improved not only the current and quantum efficiencies, more importantly, but also the power efficiency and stability. The maximum efficiencies were as high as 42.0 %, 159.5 cd A-1 and 92.7 lm W-1, and the lifetime reached 1350 hours, which are more higher than the efficiencies of 34.3% 130.2 cd A-1 and 75.0 lm W-1 and the lifetime of 859 hours of conventional tandem OLEDs. The more balanced charge generation and injection due to the simultaneous utilization of OHJ as CGL and charge injectors contributed to the significant improvement in the performance of resulting tandem OLEDs. These results fully indicate the validity of OHJ as CGL and charge injectors, and also provide a new route for the development of high performance OLEDs.
关键词： Charge generation,Organic heterojunction,Charge injector,long lifetime,high efficiency
更新于2025-09-23 15:21:01
-
Triplet acceptors with Da??A structure and twisted conformation for efficient organic solar cells
摘要： Triplet acceptors have been developed to construct high performance organic solar cells (OSCs) since the long lifetime and diffusion range of triplet excitons may dissociate into free charges instead of net recombination when the energy levels of triplet states (T1) are close to those of charge transfer states (3CT). The current triplet acceptors were designed by introducing heavy atoms to enhance the intersystem crossing, limiting their applications. Herein, two twisted acceptors without heavy atoms, analogues of Y6, were constructed with large π-conjugated core and D-A structure, proved to be triplet materials, leading to a high performance OSCs. The mechanism of triplet excitons were investigated to show that the twisted and D-A structures result in large spin orbital coupling (SOC) and small energy gap between the singlet and triplet states, and thus efficient intersystem crossing. Moreover, the energy level of T1 is close to 3CT, facilitating the split of triplet exciton to free charges. This contribution provided new insights in working mechanism of triplet excitons in OSCs.
关键词： twisted conformation,D-A structure,long lifetime exciton,triplet acceptor,organic solar cells
更新于2025-09-23 15:21:01
-
Effect of Interfacial Layers on the Device Lifetime of Perovskite Solar Cells
摘要： Organic–inorganic hybrid perovskites have excellent optical and electronic properties; exploitation of these traits has increased the power conversion efficiency of perovskite photovoltaics (PePVs) to 25.2%. However, perovskites are chemically unstable, and this deficit has critically impeded their commercialization. Device degradation occurs at the interfaces of PePVs with multiple degradation mechanisms: decomposition of organic cations in perovskites; generation of inorganic byproducts in perovskites; superoxide or trap sites at the interface of the charge-transport layer; excess charge carriers in perovskites; interfacial migration between perovskites and electrodes. This review considers the critical functions of the interfacial materials to overcome the various degradation at the interfaces of the PePVs. The working mechanisms stabilizing the interface of PePVs are categorized: passivation from atmosphere; inactivation of defect states; migration-blocking. Then, the outstanding interfacial layers made of organic materials (defect passivation, physical robustness, and chemical inactivation) and inorganic materials (chemically passivating metal oxide, physically passivating metal oxide, and low-temperature processed inorganic materials) are reviewed according to the stabilizing mechanisms. In addition, the influences of inorganic interconnecting layers in tandem PePVs are reviewed, with respect of various effects of interfacial buffer materials at the interface with perovskites.
关键词： device lifetime,interfacial layers,perovskite solar cells,stability,degradation mechanisms
更新于2025-09-23 15:21:01
-
Nitrogen-doped graphene quantum dots prepared by electrolysis of nitrogen-doped nanomesh graphene for the fluorometric determination of ferric ions
摘要： Nitrogen-doped graphene quantum dots (N-GQDs) were synthesized by direct electrolysis of a carbon cloth electrode coated with nitrogen-doped nanomesh graphene (NG) in high yield (~ 25%). The N-GQDs emit intense blue fluorescence with a quantum yield (QY) of 10% ± 3%. Meanwhile, the N-GQDs are rich in hydroxyl, carboxyl, basic pyridinic nitrogen, and nitro groups, which are conducive to strengthen the interaction between N-GQDs and Fe3+ for highly sensitive determination of Fe3+ ions. Specifically, the determination for Fe3+ was conducted at different concentrations of N-GQD solution with a wide linear range of 10–1000 μM (150 μg·mL?1) and a low detection limit of 0.19 μM (10 μg·mL?1). Moreover, the fluorescence quenching mechanism illustrated that the functional groups generated by electrochemical oxidation enhanced the interaction of N-GQDs and Fe3+, and the narrow band gap (2.83 eV) of N-GQDs accomplished electron transfer from N-GQDs to Fe3+ easily.
关键词： Fluorescence lifetime,Band gap,Dynamic quenching,Carbon cloth electrode,Electrochemical oxidation
更新于2025-09-23 15:21:01
-
Strategically Modulating Carriers and Excitons for Efficient and Stable Ultrapurea??Green Fluorescent OLEDs with a Sterically Hindered BODIPY Dopant
摘要： Ultrapure colors are vital for displays to obtain the highly desired wide color-gamut. Till now, only boron-dipyrromethene derivatives (BODIPYs) have demonstrated ultrapure full-colors but suffer from low excitons utilization efficiency as dopants in organic light-emitting diodes. It is proposed here that with a thermally activated delayed fluorophore to sensitize BODIPYs, all excitons can be recycled, which, still, is challenged by exciton loss through Dexter energy transfer (DET) from sensitizer to dopant and direct charge trapping on BODIPYs. Hence, a sterically hindered BODIPY-type dopant with a bulk substituent on the meso-position is developed to suppress DET, exhibiting a high photo-luminance quantum yield of 98% and a small full width at half maximum of 28 nm. Moreover, the device structure is elaborately designed, successfully modulating carriers and excitons to avoid charge trapping on dopant and also trigger multiple-sensitizing processes to reduce exciton loss. Consequently, a state-of-the-art maximum external quantum efficiency/power efficiency of 19.0%/85.7 lm W?1 are realized together with an ultrapure-green emission of Commission Internationale de l’Eclairage coordinates of (0.26, 0.67) and a long half-lifetime of 2947 h at an initial luminance of 1000 cd m?2.
关键词： carrier modulation,ultrapure green emission,exciton modulation,high-efficiency devices,fluorescent organic light-emitting diodes,long-lifetime devices
更新于2025-09-23 15:21:01