Improvement of Performance of Organic Light-Emitting Diodes with Both a MoO3 Hole Injection Layer and a MoO3 Doped Hole Transport Layer

We improve the performance of organic light-emitting diodes （OLEDs） with both a MoO3 hole injection layer （HIL） and a MoO3 doped hole transport layer （HTL）, and present a systematical and comparative investigation on these devices. Compared with OLEDs with only MoO3 HIL or MoO3 doped HTL, OLEDs with both MoO3 HIL and MoO3 doped HTL show superior performance in driving voltage, power efficiency, and stability. Based on the typical NPB/Alq3 heterojunction structure, OLEDs with both MoO3 HIL and MoO3 doped HTL show a driving voltage of 5.4 V and a power efficiency of 1.41 lm/W for 1000 cd/m2, and a lifetime of around 0. 88 h with an initial luminance of 5268 cd/m2 under a constant current of 190 mA/cm2 operation in air without encapsulation. While OLEDs with only MoO3 HIL or MoO3 doped HTL show higher driving voltages of 6.4 V or 5.8 V and lower power efficiencies of 1.201m/W or 1.341m/W for 1000cd/m2, and a shorter lifetime of 0.33 or 0.60h with an initial luminance of around 5122 or 5300cd/m2 under a constant current of 200 or 216mA/cm2 operation. Our results demonstrate clearly that using both MoO3 HIL and MoO3 doped HTL is a simple and effective approach to simultaneoasly improve both the hole injection and transport efficiency, resulting from the lowered energy barrier at the anode interface and the increased hole carrier density in MoO3 doped HTL.

Educational Improvement Science:The Art of the Improving Organization

Purpose:To advocate educational improvement science(EIS)as an emerging transdisciplinary field,I reflect on the three major pathways of educational advancement in human history,discern the misuses and pitfalls of reform,and theorize how education can be improved to better serve its mission.Design/Approach/Methods:Employing a multiperspectival approach,I critically re-examine educational reforms and improvements worldwide and conceptualize the emerging transdisciplinary field through an extensive literature review,etymological analysis,international comparisons,and socio-historical,-cultural and-philosophical reflections.Findings:In this paper,I advance the concept of neo-improvementalism for EIS by elucidating its philosophical assumptions,disciplinary fundamentals,and theoretical frameworks through historical and comparative lenses.I identify and construct disciplinary knowledge of EIS comprising two categories,namely,subject matter knowledge and profound knowledge,adopted from improvement science.I then highlight three methodological approaches of EIS and the building of professional improvement communities empowering individual and institutional improvement capabilities.I propose that EIS is the art of the improving organization for classes,schools,and/or more broadly defined educational agencies.Originality/Value:This study recognizes the significance of EIS and research thereon,especially discipline-building and exploration based on local characteristics in a global vision,and the cultivation of new frontiers of educational research and practices.

Improving gold recovery of Pb–Zn sulfide ore by selective activation with organic acid

Free gold and gold wrapped in sulfides are considered as the object of gold floatation. However,floatation of free gold exhibits more variables in practice.In this study, improving gold recovery of a Pb-Zn sulfide ore from Yunnan Province, China, was investigated. The results show that free gold and auriferous sulfides account for 94.99 % of total gold. Without adding organic acid in floatation, only 82 % recovery of gold could be obtained.Gold recovery in Au/Pb concentrates increases by 9.29 %with oxalate added and by 7.35 % with citric acid added,respectively, while performances of lead and arsenic nearly keep a constant. A possible reason is that free gold is of wonderful selectivity against pyrite with organic activators.A new method to enhance gold recovery is proposed.