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Solution-processed blue quantum-dot light-emitting diodes based on double hole transport layers: Charge injection balance, solvent erosion control and performance improvement
摘要： Solution processed quantum-dot based light emitting diodes (QLEDs) usually suffer from the issues of imbalanced carrier injection (especially for blue QLEDs) and solvent erosion, which prevents these devices from reaching high performance. Here we report a simple and effective method of promoting hole injection and mitigating solvent erosion simultaneously for fabricating high-performance blue QLEDs. Poly [(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(p-butylphenyl))-diphenylamine)] (TFB)/Lithium bis(trifluoromethanesulfonimide) (Li-TFSI)-doped poly(9-vinlycarbazole) (PVK) bi-layers with smooth surfaces/interfaces, prepared via a solution-process by utilizing 1,4-dioxane as the solvent for PVK, were used as hole transport layers (HTLs) for improving the performance of blue QLEDs. The TFB/Li-doped PVK based QLED records 5829 cd/m2 of maximum brightness and 5.37% of peak EQE, which represents 1.1-fold increase in brightness and ~11.5-fold increase in EQE as compared with the devices based on TFB-only HTLs. The enhanced performance for these TFB/Li-doped PVK based QLEDs can be ascribed to more efficient hole injection offered by Li-doped bilayer HTLs with smooth surfaces/interfaces and stepwise energy level alignment. The CIE 1931 color coordinates (0.15, 0.03) for these TFB/Li-doped PVK based QLEDs are close to the National Television System Committee (NTSC) standard blue CIE coordinates, showing promise for use in next-generation full-color displays. This work provides a facile solution method of fabricating TFB/Li-doped PVK bi-layers with smooth surfaces/interfaces and proves the superiority of these TFB/Li-doped PVK bi-layered HTLs in hole transport and injection for high-performance blue QLEDs.
关键词： double hole transport layers,blue quantum-dot light-emitting diodes,charge injection；Lithium salt doped hole transport layer,solvent erosion,solution processability
更新于2025-09-23 15:19:57
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<i>(Invited)</i> Mid-Infrared Colloidal Quantum Dot Based Nanoelectronics and Nano-Optoelectronics
摘要： Electronic and optoelectronic devices fabricated from colloidal quantum dots (CQDs) provide a promising path toward realizing low-cost devices with greatly simplified device fabrication procedure, owing to their solution-processability. The impact that CQD technology would bring is expected to be significant, especially in the mid-infrared application areas, which is currently dominated by epitaxial semiconductor technologies. In this work, we introduce a new generation of infrared CQDs, namely Ag2Se CQDs, which has been recently uncovered to show distinct optical absorption in the mid-infrared. We report on the fabrication of solution-processed photoconductive photodetectors and discuss our analyses on the electronic and optoelectronic characteristics of our devices. We also demonstrate the feasibility of mid-infrared photodetection with a measured peak responsivity of 0.16 mA/W at 4 μm under room temperature operation.
关键词： Ag2Se,solution-processability,photodetectors,mid-infrared,colloidal quantum dots
更新于2025-09-19 17:13:59
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Ambient Processable and Stable All-Polymer Organic Solar Cells
摘要： In this work, the way in which ambient moisture impacts the photovoltaic performance of conventional PCBM and emerging polymer acceptor–based organic solar cells is examined. The device performance of two representative p-type polymers, PBDB-T and PTzBI, blended with either PCBM or polymeric acceptor N2200, is systemically investigated. In both cases, all-polymer photovoltaic devices processed from high-humidity ambient conditions exhibit significantly enhanced moisture-tolerance compared to their polymer–PCBM counterparts. The impact of moisture on the blend film morphology and electronic properties of the electron acceptor (N2200 vs PCBM), which results in different recombination kinetics and electron transporting properties, are further compared. The impact of more comprehensive ambient conditions (moisture, oxygen, and thermal stress) on the long-term stability of the unencapsulated devices is also investigated. All-polymer solar cells show stable performance for long periods of storage time under ambient conditions. The authors believe that these findings demonstrate that all-polymer solar cells can achieve high device performance with ambient processing and show excellent long-term stability against oxygen and moisture, which situate them in an advantageous position for practical large-scale production of organic solar cells.
关键词： recombination,long-term air stability,all-polymer solar cells,ambient processability
更新于2025-09-11 14:15:04
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17% efficiency organic photovoltaic cell with superior processability
摘要： The development of organic photoactive materials, especially the new-emerging non-fullerene electron acceptors (NFAs), has enabled rapid progress in organic photovoltaic (OPV) cells in recent years. Although the power conversion efficiencies (PCEs) of the top-performance OPV cells have surpassed 16%, the devices are usually fabricated via a spin-coating method and are not suitable for large-area production. Here, we demonstrate that the fine-modification of the flexible side chains of NFAs can yield 17% PCE for OPV cells. More crucially, as the optimal NFA has a suitable solubility and thus a desirable morphology, the high efficiencies of spin-coated devices can be maintained when using the scalable blade-coating processing technology. Our results suggest that the optimization of the chemical structures of the OPV materials can improve the device performance. This has great significance in larger-area production technologies that provide important scientific insights for the commercialization of OPV cells.
关键词： non-fullerene acceptor,processability,power conversion efficiency,organic photovoltaic cells,scalable large-area production
更新于2025-09-11 14:15:04