Calibrating the Hole Mobility Measurements Implemented by Transient Electroluminescence Technology

Abstract

To date, measuring the carrier mobility in semiconductor films, especially for the amorphous organic small-molecule films, is still a big challenge. Here, we demonstrate that transient electroluminescence (TrEL) spectroscopy with quantum-dot light-emitting diodes as the platform is a feasible and reliable method to evaluate the carrier mobility of such amorphous films. The position of the exciton formation zone is precisely determined and controlled by employing a quantum dot monolayer as the emissive layer. The electrical field intensity across the organic layer is evaluated through the charge density at the electrode calculated by the transient current. Then, the charge carrier mobility is obtained by combining the electroluminescence (EL) delay time and the thickness of the organic layer. Additionally, we demonstrate that the large roughness of the organic layer leads to serious charge accumulation and, hence, a high localized electrical field, which provides preferred charge injection paths, reducing the EL delay time and underestimating the EL delay time. Therefore, a thick organic film is the prerequisite for a reliable measurement of charge carrier mobility, which can circumvent the negative effect of film roughness.

Memory-Enabled Quantum-Dot Light-Emitting Diodes

“…The QLEDs with an inverted device structure, as shown in Figure a, are fabricated. The schematic diagram shown in Figure S1 exhibits the energy level structure of each functional layer and the carrier dynamics processes. − The synthesis of ZnO NPs and the fabrication procedures of the devices are described in detail in our previous reports. − A WO x film fabricated under humidity of 24% is inserted between ITO and ZnO as the HSL, with the thicknesses of ∼3, 7, 12, and 17 nm. The WO x films were fabricated by spin-coating the precursor solution (5, 10, 15, and 20 mg/mL) at 3000 rpm for 60 s in atmosphere, followed by thermal annealing at 150 °C.…”

Machine Learning Assisted Stability Analysis of Blue Quantum Dot Light-Emitting Diodes

“…Based on the transient resolved electroluminescence analysis of QLED devices, , the operation of blue QLED devices can be simulated using a single-RC equivalent circuit model. The effectiveness of a single-RC equivalent circuit is also supported by the single semicircle feature in Nyquist plots (Figure S4a).…”

Efficient Quantum-Dot Light-Emitting Diodes Enabled via a Charge Manipulating Structure

“…Before fabrication, the ITO substrates were ultrasonically cleaned in acetone, ethanol, and deionized water in sequence for 15 min each and then dried by nitrogen flow. The detailed procedures for the device fabrication can be found in our previous reports. − The CdSe/ZnS QDs were purchased from Najing Technology Corp ., and other materials were purchased from Xi’an Polymer Light Technology Corp . The CdSe/ZnS QDs were purchased from Najing Technology Corp.…”