Spinner-Shaped Aggregation-Induced Emission Luminogens for Efficient Blue OLEDs

We have reported on spinner-shaped AIEE blue emitters, namely CTPE–PPI-PBA and CTPE-DPI-PBA, having a hybridized locally excited state (HLCT) state to harvest dark triplet excitons (Tn) via a high-lying reverse intersystem crossing (hRISC). The twisted structural conformation of these AIEE materials endows the blue emission in the film. Single-carrier device fabrication enabled both CTPE–PPI-PBA and CTPE-DPI-PBA to transport electrons and holes effectively due to proper EHOMO and ELUMO and to be employed as blue-emissive materials in OLEDs. All doped devices (CTPE-DPI-PBA:CBP) show a high exciton utilization efficiency (EUE) of 51% (8%), 52% (10%), and 76% (20%), respectively. The doped devices show a CE of 6.46, 6.92, and 7.88 cd/A, PE of 5.86, 5.93, and 6.56 lm/W, an EQE of 7.84, 7.90, and 8.98%, and a luminance of 5268, 5603, and 7803 cd/m2 at 8, 10, and 20%, respectively, with a CIE of (0.15, 0.09), (0.15, 0.09), and (0.15, 0.08), close to the NTSC standard. The doped (CTPE-DPI-PBA:CBP) devices show an insignificant roll-off efficiency due to exciton energy loss from the higher excited CTPE-DPI-PBA* to T1 excited CBP* (3.2 eV)

Nonquenching of Charge Carriers by Fe₃O₄ Core in Fe₃O₄/ZnO Nanosheet Photocatalyst

Fe₃O₄-implanted ZnO and pristine ZnO nanosheets have been synthesized hydrothermally. High-resolution scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, elemental mapping, selected area electron diffractometry, powder X-ray diffractometry, Raman spectroscopy, vibrating sample magnetometry, solid state impedance spectroscopy, UV–visible diffuse reflectance spectroscopy, and photoluminescence spectroscopy show implantation of Fe₃O₄ in ZnO nanosheets. Fe₃O₄ core with ZnO shell is of type I core/shell heterostructure which is to quench charge carriers and suppress photocatalysis. But the photocatalytic activity is not suppressed on implantation of Fe₃O₄ in ZnO nanosheets, and time controlled single photon counting lifetime spectroscopy shows that the photogenerated charge carriers are not quenched by the Fe₃O₄ core in the ZnO nanosheets. The composite nanosheets are photostable, reusable, and magnetically recoverable, revealing potential application in mineralization of organic pollutants

Enhancement of Electroluminescent Green Emission by Far-Field Coupling of Au Nanoparticles in Organic Light Emitting Diodes

Far-field surface plasmon enhanced green electroluminescence in organic light-emitting devices (OLEDs) is harvested by tuning the gold nanoparticles (Au NPs) density at the interface of the anode:hole transport layer (HTL) in OLEDs using Ir­(DMSPI)₂(acac) as emissive layer. Au NPs increases the hole injection with 35/μm² density at the indium tin oxide (ITO):<i>N</i>,<i>N</i>′-di-1-naphthyl-<i>N</i>,<i>N</i>′-diphenylbenzidine (NPB) interface and leads to enhanced emission intensity as a result of increased radiative rate (<i>k</i>_r). The Au NPs modified anode in OLEDs injects holes effectively into the NPB layer and stabilizes its energy level which results in an increase of current density. The reduced hole injection barrier (HIB) was analyzed by using the Richardson–Schottky equation. The far-field plasmonic coupling with hole injection ability of Au NPs at the ITO:HTL interface enhanced the device efficiencies at low turn-on voltage in this work. However, the anode with 6.0/μm² density of Au NPs shows poor hole injection ability into the HTL due to trapping of holes at the interface

Air Stable HyLEDs Using Efficient Electron Injection and Emitting Materials

Efficient hybrid organic inorganic light emitting diodes with an electron injection layer of 3.8 nm sized zinc oxide nanomaterials and their different emissive layers of phenanthrimidazole derivatives such as 2-phenyl-1-(3,5-dimethylphenyl) or 2-(<i>p</i>-trifluoromethylphenyl)-1-(naphthalen-1-yl) or 2-(<i>p</i>-methylphenyl)-1-naphthalen-1-yl-1H-phenanthro­[9,10-d]­imidazoles have been fabricated. The electroluminescent performances of the fabricated devices increased when compared to the reference devices. The ZnO nanolayer with 26 nm thickness and 2-(<i>p</i>-trifluoromethylphenyl)-1-(naphthalen-1-yl)-1H-phenanthro­[9,10-d]­imidazole as emissive material enhances current efficiency (η_c: 19.5 cd/A), power efficiency (η_p: 9.9 lm W^–1), external quantum efficiency (η_ex: 13.8%), and luminescence (L: 17345 cd/m²)

Biowaste-Derived Interconnected Carbon Nanosheet-Supported Iron as a Highly Stable and Excellent Electrocatalyst for Overall Water Splitting

Water splitting needs low-cost materials that can efficiently catalyze both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). We prepared biowaste-derived self-nitrogen-doped interconnected hierarchically porous carbon nanosheet Fe@PSAC as a bifunctional and ultradurable electrocatalyst for water splitting. Fe@PSAC exhibits a low overpotential of 118 mV (84 mV/dec) for HER and 231 mV (66 mV/dec) for OER @ 10 mA/cm2 in 1.0 M KOH (without iR correction). Fe@PSAC exhibits durability for 100 h with minimum potential losses of 2.9 and 2.3% for HER and OER, respectively. The turnover frequency of Fe@PSAC (0.2297/s) and IrO2 (0.0231/s) for OER and Fe@PSAC (0.0784/s) and Pt/C (0.1806/s) for HER was nearer to Pt/C and greater than IrO2, respectively. The synergy between self-nitrogen-doped interconnected hierarchically porous carbon nanosheets and iron endows excellent bifunctional activity and stability. The Fe@PSAC//Fe@PSAC water electrolyzer exhibits excellent activity at 1.58 V to reach 10 mA/cm2 with high stability for 120 h with a 3.2% potential loss. The Fe@PSAC//Fe@PSAC electrocatalyst shows an exceptional activity of 1.58 V using solar-assisted water electrolysis. The Fe@PSAC//Fe@PSAC electrode has been strongly recommended for low-cost hydrogen fuel production on a large scale

Biowaste-Derived Interconnected Carbon Nanosheet-Supported Iron as a Highly Stable and Excellent Electrocatalyst for Overall Water Splitting

Water splitting needs low-cost materials that can efficiently catalyze both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). We prepared biowaste-derived self-nitrogen-doped interconnected hierarchically porous carbon nanosheet Fe@PSAC as a bifunctional and ultradurable electrocatalyst for water splitting. Fe@PSAC exhibits a low overpotential of 118 mV (84 mV/dec) for HER and 231 mV (66 mV/dec) for OER @ 10 mA/cm2 in 1.0 M KOH (without iR correction). Fe@PSAC exhibits durability for 100 h with minimum potential losses of 2.9 and 2.3% for HER and OER, respectively. The turnover frequency of Fe@PSAC (0.2297/s) and IrO2 (0.0231/s) for OER and Fe@PSAC (0.0784/s) and Pt/C (0.1806/s) for HER was nearer to Pt/C and greater than IrO2, respectively. The synergy between self-nitrogen-doped interconnected hierarchically porous carbon nanosheets and iron endows excellent bifunctional activity and stability. The Fe@PSAC//Fe@PSAC water electrolyzer exhibits excellent activity at 1.58 V to reach 10 mA/cm2 with high stability for 120 h with a 3.2% potential loss. The Fe@PSAC//Fe@PSAC electrocatalyst shows an exceptional activity of 1.58 V using solar-assisted water electrolysis. The Fe@PSAC//Fe@PSAC electrode has been strongly recommended for low-cost hydrogen fuel production on a large scale