Showing papers by "Shuming Chen published in 2015"

Efficient Quantum-Dot Light-Emitting Diodes With 4,4,4-Tris(N-Carbazolyl)-Triphenylamine (TcTa) Electron-Blocking Layer

Abstract: 4,4,4-tris(N-carbazolyl)-triphenylamine (TcTa) with low electron mobility are used as electron-blocking layer (EBL) for quantum-dot light-emitting diodes (QD-LEDs). With TcTa EBL, electrons are effectively blocked, while holes are efficiently injected; consequently, the developed QD-LEDs exhibit significantly improved performance. Maximum external quantum efficiency of 5% and maximum luminance of 16 710 cd/m $^{\mathbf {2}}$ are achieved, which represent a 2.7-fold and a 2-fold improvement, respectively, compared with those of the devices without TcTa EBL.

Synthesis, aggregation-induced emission and electroluminescence properties of a novel compound containing tetraphenylethene, carbazole and dimesitylboron moieties

Abstract: In this paper, a new aggregation-induced emission (AIE)-active compound, 1,2-bis(4-(3,6-bis(dimesitylboranyl)-9H-carbazol-9-yl)phenyl)-1,2-diphenylethene (BBDCZPD), has been successfully synthesized. The building block of BBDCZPD comprises tetraphenylethene as the skeleton, carbazole as the hole-transporting moiety and dimesitylboron as the electron-transporting moiety. Its structure is fully characterized using elemental analysis, mass spectrometry and proton nuclear magnetic resonance spectroscopy. The thermal, electrochemical and photophysical properties of BBDCZPD are studied using thermal analysis, electrochemical methods, UV-vis absorption spectroscopy and fluorescence spectroscopy, respectively. The results show that BBDCZPD exhibits excellent thermal stability and electrochemical stability as well as AIE properties. Moreover, a multilayer organic light-emitting diode (OLED) device is fabricated by using BBDCZPD as the non-doped emitter which displays good electroluminescence performances with a turn-on voltage of 5.2 V, a maximum luminance of 5406 cd m−2 and a maximum luminance efficiency of 5.34 cd A−1. The electroluminescence properties of BBDCZPD demonstrate its potential application in OLEDs.

20.3: Optimizing the Balance of Holes and Electrons in Inverted Quantum Dot Light‐Emitting Diodes by Inserting Electron Transportation Barrier Layer

Abstract: In this study, the hole-electron balance of quantum dot lightemitting diodes (QDLED) was tuned in order to achieve efficiency enhancement. This hole-electron balance optimization was realized by inserting thin barrier layer in the electron transportation layer. Although the current density was slightly sacrificed because of the electron blocking of the barrier layer, the charge balance was improved hence leading to 123% efficiency enhancement.

Enhanced interference using microcavity structure for accurate thin film thickness measurement

Abstract: A new method based on microcavity structure is developed for accurately measuring the thickness of organic thin films. By sandwiching the thin films between a bottom reflective mirror and a top semi-reflective mirror, the interference effect is greatly enhanced. As a result, the reflectance spectra exhibit distinctive, strong, and sharp interference peaks. The interference pattern is very sensitive to the thickness of the thin films. By fitting the interference pattern with the calculated reflectance spectra, the thickness of the thin films can be accurately determined.