Adjusting the charging behavior of TiO2 with basic surfactants in an apolar medium for electrophoretic displays.

Electrophoretic displays (EPDs) are attracting attention as potential candidates for information display due to their eye-friendly nature, environmental friendliness and bistability. However, their response speed, which is closely related to the charging behavior of electrophoretic particles, is still inadequate for practical applications. Herein, five basic surfactants were employed to adjust the particle charge of titanium dioxide (TiO2) in the apolar medium Isopar L. Particle charge is strongly related to the effective surfactant coverage on surface sites, dominated by the interaction between anchoring groups and solvation chains. As a result, the electrophoretic mobility of TiO2 could be tuned between -8.09 × 10-10 and +2.26 × 10-10 m2 V-1 s-1. Due to the increased particle charge, TiO2 particles could be well dispersed in Isopar L with the assistance of S17000, T151 and T154. A black-white dual particle electrophoretic system with 2.0% (w/v) S17000 was constructed to obtain EPD devices. The EPD device gained a maximum white-and-black-state reflectivity of 41.79%/0.56% and a peak contrast ratio of 74.15. Its response time could be reduced to as low as 166.7 ms, which outperforms the majority of other black-white EPD devices.

Correction: Preventing lead leakage in perovskite solar cells and modules with a low-cost and stable chemisorption coating.

Correction for 'Preventing lead leakage in perovskite solar cells and modules with a low-cost and stable chemisorption coating' by Zongxu Zhang et al., Mater. Horiz., 2024, 11, 2449-2456, https://doi.org/10.1039/D4MH00033A.

Rational Design of Coumarin-Based Hybridized Local and Charge-Transfer Blue Emitters for Solution-Processed Organic Light-Emitting Diodes.

Hybridized local and charge-transfer (HLCT) with the utilization of both singlet and triplet excitons through the "hot excitons" channel have great application potential in highly efficient blue organic light-emitting diodes (OLEDs). The proportion of charge-transfer (CT) and locally excited (LE) components in the relevant singlet and triplet states makes a big difference for the high-lying reverse intersystem crossing process. Herein, three novel donor (D)-acceptor (A) type HLCT materials, 7-([1,1'-biphenyl]-4-yl(9,9-dimethyl-9H-fluoren-2-yl)amino)-3-phenyl-1H-isochromen-1-one (pPh-7P), 7-([1,1'-biphenyl]-4-yl(9,9-dimethyl-9H-fluoren-2-yl)amino)-3-methyl-1H-isochromen-1-one (pPh-7M), and 6-([1,1'-biphenyl]-4-yl(9,9-dimethyl-9H-fluoren-2-yl)amino)-3-methyl-1H-isochromen-1-one (pPh-6M), were rationally designed and synthesized with diphenylamine derivative as donor and oxygen heterocyclic coumarin moiety as acceptors. The proportions of CT and LE components were fine controlled by changing the connection site of diphenylamine derivative at C6/C7-position and the substituent at C3-position of coumarin moiety. The HLCT characteristics of pPh-7P, pPh-7M, and pPh-6M were systematically demonstrated through photophysical properties and density functional theory calculations. The solution-processed doped OLEDs based on pPh-6M exhibited deep-blue electroluminescence with the maximum emission wavelength of 446 nm, maximum luminance of 8755 cd m-2, maximum current efficiency of 5.83 cd A-1, and maximum external quantum efficiency of 6.54 %. The results reveal that pPh-6M with dominant 1LE and 3CT components has better OLED performance.

Preventing lead leakage in perovskite solar cells and modules with a low-cost and stable chemisorption coating.

Despite the promising commercial prospects of perovskite solar cells, the issue of lead toxicity continues to hinder their future industrial applications. Here, we report a low-cost and rapidly degraded sulfosuccinic acid-modified polyvinyl alcohol (SMP) coating that prevents lead leakage and enhances device stability without compromising device performance. Even under different strict conditions (simulated heavy rain, acid rain, high temperatures, and competing ions), the coatings effectively prevent lead leakage by over 99%. After 75 days of outdoor exposure, the coating still demonstrates similar lead sequestration efficiency (SQE). In addition, it can be applied to different device structures (n-i-p and p-i-n) and modules, with over 99% SQE, making it a general method for preventing lead leakage.

Microencapsulated Perovskite Crystals via In Situ Permeation Growth from Polymer Microencapsulation-Expansion-Contraction Strategy: Advancing a Record Long-Term Stability beyond 10 000 h for Perovskite Solar Cells.

Organic metal halide perovskite solar cells (PSCs) bearing both high efficiency and durability are predominantly challenged by inadequate crystallinity of perovskite. Herein, a polymer microencapsulation-expansion-contraction strategy is proposed for the first time to optimize the crystallization behavior of perovskite, typically by adeptly harnessing the swelling and deswelling characteristics of poly(4-acryloylmorpholine) (poly(4-AcM)) network on PbI2 surface. It can effectively retard the crystallization rate of perovskite, permitting meliorative crystallinity featured by increased grain size from 0.74 to 1.32 µm and reduced trap density from 1.12 × 1016 to 2.56 × 1015 cm-3. Moreover, profiting from the protection of poly(4-AcM) microencapsulation layer, the degradation of the perovskite is markedly suppressed. Resultant PSCs gain a robust power conversion efficiency (PCE) of 24.04%. Typically, they maintain 91% of their initial PCE for 13 008 h in a desiccated ambient environment and retain 92% PCE after storage for 4000 h with a relative humidity of 50 ± 10%, which is the state-of-the-art long-term stability among the reported contributions.