Showing papers by "Nanyang Technological University published in 1970"

Mean and Variance Control Chart Limits Based on a Small Number of Subgroups

Abstract: A previous article [9] described how a small number of subgroups can be used to set statistically sound control limits for X-bar- and R-charts. However, if the power of the charts is of paramount importance, and computational considerations are secondar..

Introduction: Pedagogy, Education and Innovation in Virtual Worlds

Abstract: Introduction Pedagogy, Education and Innovation in Virtual Worlds Guest Editors: Leslie Jarmon, University of Texas at Austin; Kenneth Y. T. Lim, Nanyang Technological University, Singapore; B. Stephen Carpenter, II, Texas A&M University,

Hokkien phonological structure

Abstract: This paper attempts to present the abstract phonological system which underlies the sounds produced when a Malayan variety of Engchun Hokkien is spoken.2 It is set within a generative framework and some attempt is made at a formalization of phonological rules.

Record High External Quantum Efficiency of 19.2% Achieved in Light-Emitting Diodes of Colloidal Quantum Wells Enabled by Hot-Injection Shell Growth

Abstract: Colloidal quantum wells (CQWs) are regarded as a new, highly promising class of optoelectronic materials thanks to their unique excitonic characteristics of high extinction coefficient and ultranarrow emission bandwidth. Although the exploration of CQWs in light-emitting diodes (LEDs) is impressive, the performance of CQW-LEDs lags far behind compared with other types of LEDs (e.g., organic LEDs, colloidal quantum-dot LEDs, and perovskite LEDs). Herein, for the first time, the authors show high-efficiency CQW-LEDs reaching close to the theoretical limit. A key factor for this high performance is the exploitation of hot-injection shell (HIS) growth of CQWs, which enables a near-unity photoluminescence quantum yield (PLQY), reduces nonradiative channels, ensures smooth films and enhances the stability. Remarkably, the PLQY remains 95% in solution and 87% in film despite rigorous cleaning. Through systematically understanding their shape-, composition- and device- engineering, the CQW-LEDs using CdSe/Cd0.25Zn0.75S core/HIS CQWs exhibit a maximum external quantum efficiency of 19.2%. Additionally, a high luminance of 23,490 cd m-2, extremely saturated red color with the Commission Internationale de L’Eclairage coordinates of (0.715, 0.283) and stable emission are obtained. The findings indicate that HIS grown CQWs enable high-performance solution-processed LEDs, which may pave the path for CQW-based display and lighting technologies.