Enhanced Polymer Light‐Emitting Diode Performance Using a Crosslinked‐Network Electron‐Blocking Interlayer

Abstract

spontaneously filled by the action of capillary forces. The response of the molecular-sieve fibers to the applied electric field was observed by an optical microscope (Leitz Orthoplan) connected to a digital camera (Panasonic).Preparation of Oriented Thin Films: A cell was designed for the deposition experiment, as shown in Figure 2. The cell consisted of two copper plates, 25 mm long, held apart by a 2 mm non-conducting spacer. A 2 mm wide glass slide was placed between the electrodes. A dilute AlPO 4 -5 colloidal suspension of concentration 2 mg fibers/ mL Fomblin was loaded onto the 2 mm wide glass slide to form a thin, liquid layer. A DC electric field of 10 kV cm ±1 was then applied for 15 min. After 15 min, most of the Fomblin leaked into the space between the electrodes and spacer. To observe the oriented film with electron microscopy, residual Fomblin was removed by heating at 300 C in an oven for one hour. The deposition process was repeated 5 times to achieve high coverage of the fibers in the glass slide.Dye-Loaded AlPO 4 -5 Crystals and UV-Vis Spectra Measurement: The AlPO 4 -5 crystals were first calcined at 600 C for 10 h in a continuous flow of oxygen to remove organic material from the pores. PNA (99 %, from Aldrich) was then incorporated into the pores of the crystals by gas loading at 100 C and by autogenous pressurization after being left overnight. The dye-loaded crystals appeared yellow. Excess PNA was then washed from the exterior of the crystals by dispersing the crystals in ethanol. Crystals were then collected by centrifugation at 15 300 rpm for one hour. The crystals remained yellow after washing. A dye-loaded oriented film was created by 10 depositions cycles from a suspension of 5 mg fibers per mL of Fomblin. The UV-vis transmission spectra were collected by a PerkinElmer Lambda 900 UV/Vis/Near-infrared spectrometer equipped with an adjustable polarizer.

Solution processed naphthalene diimide derivative as electron transport layers for enhanced brightness and efficient polymer light emitting diodes

“…Table 1 summarizes typical results for our measured PLEDs, illustrating the enhancement seen in different parameters when switching to DC18. For the F8BT devices, the maximum brightness The overall brightness and efficiency of the reference devices, while not the highest reported, remain consistent with reported results using MEH PPV and F8BT in similar device structures, [34][35][36] providing evidence that they are a reproducible testing platform for novel injection layers. The brightness and turn on voltages are improved for both active layer polymers with the inclusion of DC18, but the F8BT devices see a larger efficiency improvement compared to the MEH PPV devices.…”

Improving Film Formation and Photovoltage of Highly Efficient Inverted‐Type Perovskite Solar Cells through the Incorporation of New Polymeric Hole Selective Layers

“…The CV curves showed that reversible oxidations occurred in both HSLs and the onset of oxidation potential for HSL1 and HSL2 are located at 0.85 and 1.08 V versus SCE, respectively. [ 48 ] The redox potential of Fc/ Fc + internal reference is 0.49 V versus SCE. The HOMO energy levels of HSL1 and HSL2, determined by calculating from the empirical formula of E HOMO = − e ( E ox + 4.8 − E 1/2, (Fc/Fc+) ), are −5.16 and −5.39 eV, respectively.…”

Crosslinkable Hole‐Transport Layer on Conducting Polymer for High‐Efficiency White Polymer Light‐Emitting Diodes

“…However, for polymer-based LEDs, where solution-based casting or spin-coating is the basic way to form films, it is very challenging to form multilayer structures, because of solvent erosion of previously deposited layers during spin-coating. [4] To overcome this problem, a crosslinkable HTL has been developed for fabricating highefficiency LEDs, such as those based on fluorescent conjugated polymers and red phosphorescent emitters. [5][6][7][8][9] For blue LEDs, because most of the blue phosphorescent emitters possess quite high energy levels at their highest occupied molecular orbital (HOMO) (for example, the HOMO for bis(4′,6′-difluorophenylpyridinato) tetrakis(1-pyrazolyl)-borate (FIr6) is -6.1 eV), it is quite difficult to obtain efficient hole injection.…”