Realizing External Quantum Efficiency over 25% with Low Efficiency Roll-Off in Polymer-Based Light-Emitting Diodes Synergistically Utilizing Intramolecular Sensitization and Bipolar Thermally Activated Delayed Fluorescence Monomer

Since polymer-based light-emitting diodes(PLEDs)arewellsuited building blocks for large-area and low-cost flexible display equipment,state-of-the-art thermally activated delayed fluorescence(TADF)PLEDs are in high demand.To respond to this demand,light-emitting TADF units have initially been modified with electron-transporting units to balance the carrier transport of regiorandom TADF polymers,and simultaneously,an intramolecular sensitizing strategy has also been employed by covalently incorporating TADF sensitizers with light-emitting TADF units and hosts in conjugated polymers to accelerate the spin-flip of triplet excitons.Superior photophysical properties have been achieved by a rational regulation of the proportions of each component,achieving a photoluminescence quantumyield of 90%,an extremely high rate of reverse intersystem crossing of 3×106 s−1,and a relatively low nonradiative decay rate of around 105 s−1.As a result,the solutionprocessed PLEDs can attain an external quantum efficiency(EQE)value of 25.4%with emission peaks of around 550 nm,representing record-high performance for PLEDs.The efficiency roll-off can also be significantly suppressed,maintaining an EQE value of 24.2%at 1000 cd/m2 with ideal efficiency roll-off of lower than 5%.Encouragingly,this work provides a valid strategy to tackle the imperative need for PLEDs with high EQE and low efficiency roll-off.

Efficient deep blue OLEDs with extremely low efficiency roll-off at high brightness based on phenanthroimidazole derivatives

Phosphorescent and thermally activated delayed fluorescence(TADF)emitters can break through the spin statistics rules and achieve great success in external quantum efficiency(over 5%).However,maintaining high efficiency at high brightness is a tremendous challenge for applications of organic light emitting diodes.Hence,we reported two phenanthroimidazole derivatives PPI-An-CN and PPI-An-TP and achieved extremely low efficiency roll-off with about 99%of the maximum external quantum efficiency(EQEmax)maintained even at a high luminance of 1000 cd/cm2 based non-doped devices.When doping the two materials in CBP(4,4'-bis(N-carbazolyl)-1,1'-biphenyl),the doped devices still exhibited excellent stability at high brightness with CIEy≈0.07 and low turn-on voltage of only 2.8 V.The state-ofthe-art low efficiency roll-off makes the new materials attractive for potential applications.It is the first time that the Fragment Contribution Analysis method has been used to analyze the excited state properties of the molecules in the field of OLEDs,which helps us understand the mechanism more intuitively and deeply.

Lattice reconstruction for mixed-halide blue perovskite light-emitting diodes with high brightness,outstanding color stability and low efficiency roll-off

We report a simple,effective,and universal lattice reconstruction approach to improve the quality of perovskite films by using nonpolar solvents with high Gutmann donor numbers(DNs).We find that high-DN nonpolar solvents,for instance,ethyl acetate,can interact with perovskite precursors.Such a solvent can make the perovskite lattice more ordered and“harder”and promote the formation of heterostructures with low-dimensional perovskite impurities and residual solvent molecules.As a result,the latticereconstructed perovskite films exhibit reduced defect densities and suppressed ion migration.The resultant mixed-halide blue perovskite light-emitting diodes(PeLEDs)show greatly enhanced tolerance to high driving current densities and voltages,demonstrating high brightness,outstanding color stability and low efficiency roll-off.Our work provides a deep understanding of the interactions between nonpolar solvents and perovskites and offers useful guidelines for further development of high-power PeLEDs.

A Solution for Scalable Routing in Depth Divisions-Based DUSNs via Adding a Scalable Parameter to Control Depth Clusters: Creating an Energy Efficient and Low Delay NI-Independent Communication Protocol

Due to effectiveness of network layer on general performance of networks, designing routing protocols is very important for lifetime and traffic efficiency in wireless sensor networks. So in this paper, we are going to represent an efficient and scalable version of depth-based routing (DBR) protocol that is limited by depth divisions-policy. In fact the new version is a network information independent routing protocol for acoustic communications. Proposed method by use of depth clustering is able to reduce consumed energy and end-to-end delay in dense underwater sensor networks (DUSNs) and this issue is proved by simulation.

High voltage generator circuit with low power and high efficiency applied in EEPROM

This paper presents a low power and high efficiency high voltage generator circuit embedded in electrically erasable programmable read-only memory（EEPROM）.The low power is minimized by a capacitance divider circuit and a regulator circuit using the controlling clock switch technique.The high efficiency is dependent on the zero threshold voltage（V_（th）） MOSFET and the charge transfer switch（CTS） charge pump.The proposed high voltage generator circuit has been implemented in a 0.35μm EEPROM CMOS process.Measured results show that the proposed high voltage generator circuit has a low power consumption of about 150.48μW and a higher pumping efficiency（83.3%） than previously reported circuits.This high voltage generator circuit can also be widely used in low-power flash devices due to its high efficiency and low power dissipation.

More Discussion on High Efficiency & Low Cost Clean Steel Production Platform

The construction of high efficiency, low cost clean steel platform is one of the common key technologies concerning efficiency, quality and cost. It is basic and universal and not only applicable in the R&D and production of "high-end" products, but also in the production of bulk ordinary steel products. The platform of high efficiency, low cost clean steel is the important direction of modern steel technology progress and has great significance on the competitiveness of each steel plant. The research of high efficiency, low cost platform not only involves the production and management of the steel plant, but also the academic research field (process engineering and dynamic operation) and theories and methods innovation of engineering design (theory and method of dynamic-precision design). The integrated theory and method of high efficiency and low cost clean steel platform is the binding point of metallurgical process engineering and material engineering. Different types of high efficiency, low cost clean steel platform should combine with the corresponding rolling process and iron making process so that high efficiency, low cost clean steel manufacturing system would come into being.

Dynamic Power Dissipation Control Method for Real-Time Processors Based on Hardware Multithreading

In order to eliminate the energy waste caused by the traditional static hardware multithreaded processor used in real-time embedded system working in the low workload situation, the energy efficiency of the hardware multithread is discussed and a novel dynamic multithreaded architecture is proposed. The proposed architecture saves the energy wasted by removing idle threads without manipulation on the original architecture, fulfills a seamless switching mechanism which protects active threads and avoids pipeline stall during power mode switching. The report of an implemented dynamic multithreaded processor with 45 nm process from synthesis tool indicates that the area of dynamic multithreaded architecture is only 2.27% higher than the static one in achieving dynamic power dissipation, and consumes 1.3% more power in the same peak performance.

Novel thioxanthone host material with thermally activated delayed fluorescence for reduced efficiency roll-off of phosphorescent OLEDs

2,7-Di（9,9-dimethyl-9H-fluoren-l-yl）-9H-thioxanthen-9-one （DMBFTX） with thermally activated delayed fluorescence （TADF） was well designed and synthesized. The phosphorescent organic lightemitting device （PHOLED） based on this novel TADF host material displays a stable red phosphorescence region, a peak external quantum efficiency （EQE） value of 12.9% and a low EQE roll-off of 38.8%at a luminance of 10000 cd/m2, which is benefited from the reverse intersystem crossing （RISC） of TADF host and less populated triplet exitons. Notably, the red device based on the TADF host DMBFrX exhibits superior electroluminescence performance and reduced efficiency roll-offcompared with the one hosted by commercially available host 1,3-bis（9-carbazolyl）benzene （mCP）, illustrating the high potential of employing the TADF host material with small energy gap to reduce efficiency roll-off in PHOLED.

Scaling trends in energy recovery logic:an analytical approach

This paper presents an analytical model to study the scaling trends in energy recovery logic.The energy performance of conventional CMOS and energy recovery logic are compared with scaling the design and technology parameters such as supply voltage,device threshold voltage and gate oxide thickness.The proposed analytical model is validated with simulation results at 90 nm and 65 nm CMOS technology nodes and predicts the scaling behavior accurately that help us to design an energy-efficient CMOS digital circuit design at the nanoscale.This research work shows the adiabatic switching as an ultra-low-power circuit technique for sub-100 nm digital CMOS circuit applications.