Lifetime Extension Research Articles

Stimulated Generation of Magnetrons powered below the Self-Excitation Threshold Voltage

Modern CW or pulsed superconducting accelerators of megawatt beams require efficient RF sources controllable in phase and power. Typically, the costs of the RF sources and their operation are a significant part of the total cost for large-scale projects. The efficiency of the traditional RF sources (klystrons, IOTs, solid-state amplifiers) is lower in comparison to magnetrons and the cost of RF power per Watt is significantly higher. Therefore the magnetron-based controlled in phase and power RF sources could significantly reduce the capital and operation costs of ADS and SNS like projects or, e.g., the Electron-Ion Collider projects unlike the traditional RF sources. Currently, a number of works suggests the use of magnetrons controlled by a resonant injected (injection-locking) RF signal instead of traditional RF sources. We developed a new approach to controlling magnetrons for superconducting accelerators with megawatts beams In the presented work we describe an innovative technique producing the “stimulated” RF generation of magnetrons powered below the self-excitation threshold voltage. This was predicted and substantiated by a recently developed kinetic (electrodynamic) model of magnetron operation. The technique allowing operation in CW and pulse modes has been experimentally verified and studied. It allows stable, controllable in phase and power operation of magnetrons providing efficiency higher than other types of RF power sources. The technique does not require high voltage pulse modulators for a pulsed RF generation. It also looks to be a promising opportunity to improve magnetron reliability and extend life time. Measured characteristics of the developed technique, its experimental verification and verification of the kinetic model briefly presented in the text are discussed in our work.

Assessment of a rotor blade extension retrofit as a supplement to the lifetime extension of wind turbines

Abstract. The potential lifetime of wind turbine components is usually not fully utilized as the site conditions are less severe than assumed in the turbine design. Operators of wind farms can make use of the excess fatigue budget to increase the energy yield and thus decrease the levelized cost of energy (LCoE). To achieve this, the lifetime of the turbine can be extended until the fatigue budget is exhausted. Alternatively, a rotor blade extension (RBE) is an option to increase the energy yield of a wind turbine. An RBE increases the blade length and thus the swept area and the energy yield. An RBE also increases the loads on the turbine, however. Higher fatigue loads in turn reduce the fatigue budget of a turbine. This study investigates whether the use of an RBE is advantageous compared with a sole lifetime extension (LTE). As the use case, a commercial 1.5 MW turbine located in northern Germany was investigated. Aeroservoelastic multibody load simulations and simplified static load simulations were verified with each other. These simulations revealed the loads to determine the fatigue budget of the turbine components. Since the blade became the critical component when a certain RBE length was exceeded, the blade was subjected to a structural fatigue analysis. The fatigue analysis focused on the trailing-edge bond line which became critical when lead–lag loads increased with blade length. Finally, the energy production gains due to LTE and RBE were assessed. For the use case turbine, this study revealed an LTE of 8.7 years after a design life of 20 years with an additional energy yield of 43.5 %. Moreover, the extension of the 34 m blade with an RBE length of 0.8 m further increased the yield by 2.3 %.

Conflicting consequences of price-induced product lifetime extension in circular economy: The impact on metals, greenhouse gas, and sales of air conditioners

This study examined the effects of product price increases on metal consumption, greenhouse gas (GHG) emissions, and product sales via changes in the product replacement decisions of consumers. A dynamic discrete choice model was applied to air conditioners (ACs) in Japan to determine these effects when product price is increased by from 5% to 30% in 5% increments. To illustrate, a 5% increase in air conditioners was shown to reduce consumption of iron, copper, and aluminum by six, one, and two thousand tons, respectively, while increasing GHG emissions by 506 kt-CO2 eq. and decreasing product sales by 56 billion Japanese yen. Thus, product price increases for ACs led to a reduction in material consumption while decreasing product sales. The effect on GHG emissions depends on the level of the product price increase. These interactions suggest that consumers will use products longer so long as the value of the product's enhanced durability and longevity matches the increased price of the product. Efforts to improve product durability and longevity, however, will require that AC companies explore new business models in order to cope with the anticipated decrease in product sales as the transition to a circular economy continues.

Privacy Protection NAND Flash System With Flexible Data-Lifetime Control by In-3-D Vertical Cell Processing

This article proposes a privacy-aware data-lifetime control NAND flash system (PDLCS) that changes the data-lifetime flexibly for privacy protection. The proposed PDLCS consists of four proposed techniques: 1) inverse Huffman-coding ${V}_{{\text {TH}}}$ modulation (IHVM); 2) immediate delete command (IDC); 3) adaptive lifetime extension (ALE); and 4) adaptive lifetime reduction (ALR), with In-3-D vertical cell processing of 3-D NAND flash memories. This system realizes both short- and long-term data lifetimes. Furthermore, data lifetime can be extended or shortened at any time. This cannot be realized by conventional 2-D NAND flash memories because data lifetime is controlled by the lateral charge migration in 3-D NAND flash memories. The proposed PDLCS secures privacy data and, thus, is a universal solution for future secure storage, which is not resolved by software techniques.

High Areal Capacity Porous Sn-Au Alloys with Long Cycle Life for Li-ion Microbatteries

Long-term stability is one of the most desired functionalities of energy storage microdevices for wearable electronics, wireless sensor networks and the upcoming Internet of Things. Although Li-ion microbatteries have become the dominant energy-storage technology for on-chip electronics, the extension of lifetime of these components remains a fundamental hurdle to overcome. Here, we develop an ultra-stable porous anode based on SnAu alloys able to withstand a high specific capacity exceeding 100 µAh cm−2 at 3 C rate for more than 6000 cycles of charge/discharge. Also, this new anode material exhibits low potential (0.2 V versus lithium) and one of the highest specific capacity ever reported at low C-rates (7.3 mAh cm−2 at 0.1 C). We show that the outstanding cyclability is the result of a combination of many factors, including limited volume expansion, as supported by density functional theory calculations. This finding opens new opportunities in design of long-lasting integrated energy storage for self-powered microsystems.

Time-dependent reliability analysis of service-proven quay walls subject to corrosion-induced degradation

The assessment of service-proven quay walls subject to corrosion-induced degradation is inherently a time-dependent reliability problem. Two major challenges are the modelling of corrosion and taking into account the decrease of epistemic uncertainty throughout the quay wall's service life. The main objective of this study is to examine the probability of failure, despite successful past performance, when the quay wall is subject to corrosion and randomly imposed variable loads. The development of the annual failure rate is modelled using crude Monte Carlo and by performing a first-order system reliability analysis. The annual failure rates found for service-proven quay walls vary over time. For those with successful service histories and subject to low corrosion rates, the highest reliability indices are observed in the first year of the service life, whereas with higher corrosion rates the final year prevails. In general, it seems more practical to evaluate reliability on an annual basis rather than over longer time periods, since the latter will introduce an iterative procedure to determine the wall's remaining lifetime. The key findings of this study can be crucial for the lifetime extension of existing quay walls, and presumably also for other service-proven geotechnical structures subject to corrosion.

Battery aging conscious intelligent energy management strategy and sensitivity analysis of the critical factors for plug-in hybrid electric buses

The aim of this paper is to propose a battery aging conscious energy management strategy. The initial design of an energy management strategy is a significant point, in order to fulfill the efficiency goals in a short term. However, with the aging, the initial conditions vary. The new trend of digitalization allows to monitor the operation, having the possibility to update the developed first strategy in a long term. Therefore a methodology for updating the energy management strategy throughout the bus lifetime is proposed, in order to improve the operation costs and extend the battery lifetime. This update is based on a dynamic programming optimization, tuning the fuzzy logic membership functions and output. Operation costs improvements up to 32.5% are obtained beside a rule-based strategy and a BT lifetime extension of 5.64% is reached. A sensitivity analysis for identifying the critical factors affecting the plug-in hybrid electric bus energy management strategy has been carried out. Auxiliary consumption variation and battery lifetime throughout the bus lifetime have been identified as the most affecting factors. • Development of an aging conscious energy management strategy for plug-in hybrid electric buses. . • Methodology for updating the energy management strategy throughout the bus lifetime. • Critical factors sensitivity analysis for plug-in hybrid electric buses energy management strategy. • Battery state of health influence in the operation costs during the lifetime.

Thermally Activated Delayed Photoluminescence: Deterministic Control of Excited-State Decay.

Thermally activated photophysical processes are ubiquitous in numerous organic and metal-organic molecules, leading to chromophores with excited-state properties that can be considered an equilibrium mixture of the available low-lying states. Relative populations of the equilibrated states are governed by temperature. Such molecules have been devised as high quantum yield emitters in modern organic light-emitting diode technology and for deterministic excited-state lifetime control to enhance chemical reactivity in solar energy conversion and photocatalytic schemes. The recent discovery of thermally activated photophysics at CdSe nanocrystal-molecule interfaces enables a new paradigm wherein molecule-quantum dot constructs are used to systematically generate material with predetermined photophysical response and excited-state properties. Semiconductor nanomaterials feature size-tunable energy level engineering, which considerably expands the purview of thermally activated photophysics beyond what is possible using only molecules. This Perspective is intended to provide a nonexhaustive overview of the advances that led to the integration of semiconductor quantum dots in thermally activated delayed photoluminescence (TADPL) schemes and to identify important challenges moving into the future. The initial establishment of excited-state lifetime extension utilizing triplet-triplet excited-state equilibria is detailed. Next, advances involving the rational design of molecules composed of both metal-containing and organic-based chromophores that produce the desired TADPL are described. Finally, the recent introduction of semiconductor nanomaterials into hybrid TADPL constructs is discussed, paving the way toward the realization of fine-tuned deterministic control of excited-state decay. It is envisioned that libraries of synthetically facile composites will be broadly deployed as photosensitizers and light emitters for numerous synthetic and optoelectronic applications in the near future.

Analysis of power allocation strategies in the smoothing of wind farm power fluctuations considering lifetime extension of BESS units

The wind farm output power fluctuates because of the random intermittent speed of the wind. When the capacity of wind farms increases, the effect of wind power fluctuations on the power system stability becomes more considerable. Therefore, the fluctuations are mitigated by use of Battery Energy Storage System (BESS) units. The high cost of the BESS has always been one of the major challenges in the investment for the wind farms. Therefore, it is necessary to protect the lifetime of BESS units used in wind farms by using a proper power allocation for them. In this paper, a three-layer control method is proposed to reduce the required BESS in the wind farm, while satisfying the utility constraint and increasing the lifetime of the BESS units. Moreover, 9 power allocation strategies for charging/discharging process in the BESS units are investigated and the most appropriate strategy is introduced. The simulation results based on the output power data of a real 99 MW wind farm indicate that the proposed heuristic-based method is very successful in controlling the switching actions, because the maximum and the average achieved value of switching actions are equal to 2 and 1.14, respectively. In addition, the variance of the Number Of charging/discharging Cycles (NOC) of BESS units is 0.33 which reveals that the number of BESS units with switching actions higher than the average is very small. Moreover, the low average value of life-expended of all the BESS units represents the efficient performance of the proposed control method.

Conjugated polymers for functional applications: lifetime and performance of polymeric organic semiconductors in organic field‐effect transistors

Developments in the performance of organic field‐effect transistors have produced devices with similar, and in some cases even better, charge transport properties compared to amorphous silicon. For devices to be viable in more appliances and industry, their lifetime must be improved. However, advances in lifetime are lagging compared to other properties, such as charge carrier mobilities. The lack of a standardized methodology to evaluate the lifetime adds complications, as this property can mostly be compared qualitatively rather than quantitatively. Still, extension of lifetime has been realized through intelligent design of device architecture or alterations that benefit the stability of a device's active organic semiconducting polymer. More unique methods to improve the stability of organic field‐effect transistors, such as blending the semiconducting layer with other polymers or imposing micro‐/nanostructures in the device, have yielded positive results. © 2020 Society of Chemical Industry

Position isomers of Ru(II) polypyridine complexes with tunable photophysical properties, aggregation-induced phosphorescence enhancement and application in triplet-triplet annihilated upconversion

Three Ru(II) polypyridine complex isomers (Ru-2-DP, Ru-3-DP and Ru-5-DP) have been synthesized using phenanthroline-based isomers containing 4-(2,2-diphenyl-vinyl)-phenyl unit. Their photophysical properties are systematically investigated. Notably, three coordination isomers exhibit much longer triplet lifetimes compared to the model complex [Ru(bpy)2(Phen)]2+. The density function theory calculations reveal that the extension of triplet lifetimes is attributed to the establishment of an excited-state equilibrium between the intraligand (3IL) state and the metal-to-ligand charge-transfer (3MLCT) state. In aggregates, Ru-2-DP shows an interesting aggregation-induced phosphorescence enhancement (AIPE) property. The phosphorescence intensity of Ru-2-DP increases by 16.2-fold from acetonitrile solution to aggregated state. However, Ru-3-DP and Ru-5-DP are AIPE-inactive. Single-crystal analyses show substituent position has a dramatic effect on intramolecular steric hindrance, leading to different molecular conformation and packing pattern. Using three coordination isomers as triplet sensitizers for triplet-triplet annihilated (TTA) upconversion, Ru-3-DP and Ru-5-DP display obvious upconversion properties, but it's quite the opposite for Ru-2-DP. Experimental data demonstrate 3- and 5-positions of phenanthroline, especially 3-position, are beneficial to enhance intersystem crossing and triplet-triplet energy transfer and for the resulting upconverted efficiency enhancement. This work definitely suggests that minor structural change may have major effects upon the solid-state spectroscopic properties and TTA upconversion performances, which provides a rational basis for designing excellent solid phosphorescent materials and triplet sensitizers.

Fatigue Prediction for Extended Riser Life and Improved Vessel-Response Analysis

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper OTC 29531, “Flexible-Riser Fatigue Counter Developed From Field Measurements and Machine-Learning Techniques,” by Christoffer Nilsen-Aas, Jan Muren, and Håvard Skjerve, 4Subsea, et al., prepared for the 2019 Offshore Technology Conference, Houston, 6–9 May. The paper has not been peer reviewed. Copyright 2019 Offshore Technology Conference. Reproduced by permission. This paper presents a fatigue-prediction methodology designed to extend the life of unbonded flexible risers and improve the accuracy of floating production, storage, and offloading (FPSO) vessel response analysis. The methodology combines measured-motion-response, maritime-environment, and process data to improve traditional time-domain dynamic analysis models, along with machine-learning (ML) techniques to develop a heading model for the FPSO. Introduction Life extension of unbonded flexible risers is a challenge because of uncertainties associated with key parameters driving deterioration, such as how the riser was designed, manufactured, and installed and how it is operated. Fatigue service life is calculated during the design phase using models based on field-specific environmental data derived for the area and loads for the required design conditions per project specifications and international standards. Using real measured data from the riser motions and from environmental sources can reduce uncertainties significantly, improving life-extension analysis for fatigue and other failure drivers. These data, when combined with high-end engineering assessments and considerations on data reliability, provide better insight and contribute to continued operations with acceptable risk for the risers. The complete paper presents a methodology that uses measured environmental data and FPSO and riser response data in an ML environment to build more-realistic riser-response and fatigue-prediction models. A case example is presented for the risers suspended from the FPSO Fluminense producing from the BijupirÁ and Salema fields offshore Brazil. Because FPSO heading is important for vessel dynamics, especially roll, and the vessel dynamics are a key factor in the riser dynamics at this field, initial focus was on predicting vessel heading relative to swell. The heading model developed by ML showed good agreement and was used as a key tool in a traditional fatigue analysis. This analysis was based on historical sea states from the last 2 years. The results show that the fatigue analysis from the design phase is conservative and lifetime extension is achievable. Because the fully instrumented measurement campaign ended after 4 months, the work focused on using all captured data to provide improved insight and develop both traditional simulation and ML models. For future fatigue predictions based on the developed fatigue counter, the objective is to maintain accuracy with less instrumentation. In the present phase, FPSO and riser-response data from the 4-month campaign have been used to establish a correlation between riser behavior, environmental data, and FPSO heading and motion. Calibration of a traditional numerical model is performed using measurement data along with a direct waves-to-fatigue prediction based on modern ML techniques. The ongoing work illustrates how real environmental data and response monitoring can reduce uncertainties and improve and extend flexible-riser life.

Abstract 26: Scenario Analyses of Lifetime Cost-effectiveness of Icosapent Ethyl in REDUCE-IT

Background: The Reduction of Cardiovascular Events with Icosapent Ethyl (IE)–Intervention Trial (REDUCE-IT) showed that patients with elevated baseline triglyceride and well controlled LDL-C levels on statins had a 30% lower risk of first and recurrent ischemic events, including cardiovascular death, in those who received 2 g of IE twice daily compared to placebo. In this study, we conducted scenario analyses of lifetime cost-effectiveness (CE) of IE compared with standard care (SC) alone. Methods: We applied treatment effects from REDUCE-IT, health care costs from national sources, and costs for IE of $4.16 a day and conducted a combination CE analysis utilizing patient level in-trial cost and clinical outcomes and long-term costs, events, and life expectancy derived from Markov simulation models. The model projected lifetime health care costs, cardiovascular events, survival, and quality-adjusted life-years (QALYs) for IE versus SC in eligible patients from a payer perspective. Scenario analyses included lifetime extension of in-trial base case and other four cases. In the lifetime base case, IE adherence and treatment effects would be assumed to reduce linearly beginning after the trial period and extending to 20 years post baseline. In the best case, patients in the IE group would adhere to treatment persisting for the rest of their lives. In the worst case, patients in the treatment group would stop adhering to IE immediately after the trial period. In the fourth scenario, patients would continue to take treatment drug but the effect of the drug would decrease effectiveness over 15 years. In the fifth scenario, patients in the treatment group would have disutility from taking IE. Results: The QALYs for IE and SC were 3.34 and 3.27 in-trial and 11.61 and 11.35 lifetime, respectively. Without background cost, the mean costs for IE and SC in-trial were $23,926 and $24,563 and lifetime $87,077 and $88,912, respectively. IE was a dominant strategy, in-trial 73.2% and lifetime 71.6% of simulations. In probabilistic sensitivity analysis, 91.9% of simulations indicated that IE would be cost-effective (i.e., below $50,000 per QALY gained). In the lifetime base case, the probability of CE at the $50,000, $100,000, and $150,000 threshold was 91.6%, 92.6%, and 93.2% of simulations, respectively. In the best case, the probability that IE was cost-effective was 98.4%, 99.0%, and 99.3% at the $50,000, $100,000, and $150,000 per QALY gained thresholds, respectively. In the worst case scenario, the probability that IE was cost-effective was 88.1%, 89.4%, and 90.5% at the $50,000, $100,000, and $150,000 per QALY gained , respectively. Similar results were shown in the fourth and fifth scenarios. Conclusions: Icosapent ethyl at a cost of $4.16/day was shown to be cost-effective at willingness-to-pay thresholds of $50,000 per QALY, and a dominant strategy in all post trial persistence-of-IE-effect scenarios.

Elastic limit load resource when reaming holes in turbine rotor discs

The main topic of the article is the evaluation of load capacity by elastic stress analysis of impulse steam turbine rotors with bore drilled discs used for pressure equalization. Long-time operation of such turbines leads to fatigue fractures. The authors have analyzed stress distribution around the holes in turbine rotors in their nominal state and after reaming, which is the preferred method of removing fractures. Two approaches were used in analysis of bore drilled disc problem: continuous model and its mathematical solution and numerical based on finite element modeling. Both confirmed co-existence of stress concentration and crack initiation. Results show significant range for possible holes reaming - even with lowering stress level at critical area. These results were successfully used in overhaul practices and further turbine life time extension. It also allows to predict optimum hole layout and sizing at the design process for possible rotor disc notch effect reduction.

CdSe/CdS/CdTe Core/Barrier/Crown Nanoplatelets: Synthesis, Optoelectronic Properties, and Multiphoton Fluorescence Upconversion.

Colloidal two-dimensional (2D) nanoplatelet heterostructures are particularly interesting as they combine strong confinement of excitons in 2D materials with a wide range of possible semiconductor junctions due to a template-free, solution-based growth. Here, we present the synthesis of a ternary 2D architecture consisting of a core of CdSe, laterally encapsulated by a type-I barrier of CdS, and finally a type-II outer layer of CdTe as so-called crown. The CdS acts as a tunneling barrier between CdSe- and CdTe-localized hole states, and through strain at the CdS/CdTe interface, it can induce a shallow electron barrier for CdTe-localized electrons as well. Consequently, next to an extended fluorescence lifetime, the barrier also yields emission from CdSe and CdTe direct transitions. The core/barrier/crown configuration further enables two-photon fluorescence upconversion and, due to a high nonlinear absorption cross section, even allows to upconvert three near-infrared photons into a single green photon. These results demonstrate the capability of 2D heterostructured nanoplatelets to combine weak and strong confinement regimes to engineer their optoelectronic properties.

An in depth characterization of the spectroscopic properties and laser action of 10 at% Yb doped Y3ScxAl5-xO12 (x = 0.25, 0.5, 1.0, 1.5) transparent ceramics

We report on the spectroscopic and laser emission properties of 10 at% Yb:Y3ScxAl5-xO12 (Yb:YSAG) ceramic varying the amount of Sc (x) ranging from x = 0.25 to x = 1.5. The samples were fabricated by a solid state reaction method followed by vacuum sintering and annealing in air. The spectroscopic investigation has evidenced an increased broadening in both the absorption and the emission spectra for increasing Sc content, as well as an extension of lifetime at increased Sc content. Concerning the laser performance, the maximum slope efficiency, i.e. 76.6%, was obtained with the sample with x = 0.25 while the largest tuning range, i.e. 81 nm, with the sample having the highest concentration of Sc ions (x = 1.5); a steady broadening in the tuning bandwidth for increasing Scandium content was measured.

Maximising network lifetime and energy efficiency of wireless sensor network using group search Ant lion with Levy flight

Wireless sensor network (WSN) is one of the emerging techniques, providing pervasive computing for different implementations. Some of the renowned problems in WSN are energy consumption, as well as, the extension of network lifetime. Moreover, cluster head (CH) selection is one of the essential criteria since it has direct communication with the base station. Several researchers are in progress in designing the energy-efficient model. However, the problems are not yet rectified completely, which leads to the poor performance of WSN. This study intends to maximise the lifetime of the WSN by introducing an efficient CH selection algorithm. The CH selection is a crucial step that aids in improving the energy efficiency and network lifetime of a WSN. This study proposes a hybrid optimisation process named group search ant lion with Levy flight for choosing the CH in WSN. The proposed model is compared to the conventional models such as genetic algorithm, particle swarm optimisation, artificial bee colony, group search optimisation, ant lion optimisation and cuckoo search. The outcome of the simulation result shows the superiority of the proposed model by prolonging the lifetime of the network.

Examining the Properties of Natural Ester Oils with Antioxidants and Nano Powders for Power Applications

In this cutting edge world, electrical vitality is the significant thing to make due on the planet. An ongoing examination has prevailed that the oil by items are accessible just for not many years. Along these lines, following barely any years substitution of mineral oil is vital because of its debasement of protection. In this paper, the oil picked is Neem oil, sunflower oil, Mahua oil and Rice grain oil is treated with antioxidants(cancer prevention agents) and nano powders. "Breakdown voltage, flash point, fire point, viscosity and acidity are estimated in consonance with principles". To diminish the oxidation security normal and manufactured antioxidants(cancer prevention agents) are liked, and Nano powders are additionally utilized for improving the properties of the oil. Engineered cell reinforcements, for example, Beta Carotene and TBHQ and selenium are favored as normal cancer prevention agents. When the expansion of cancer prevention agents and nano powders the estimations were finished. After cancer prevention agents and Nano powders are included, the property of the transformer oil is expanded. By doing this investigation, the transformer oil is utilized for reuse reason and it has a more extended lifetime.

Theorizing self‐repairers' worldview–personhood to advance new thinking on extended product lifetimes

AbstractThe ecological and societal problems caused by product obsolescence and consumerism in modern economies constitute a “wicked human‐made problem” of significant magnitude. Current (old) ways of thinking cannot address these problems. Accordingly, in this paper, we critically explore the novel idea of integrated personhood and worldviews to theorize research on self‐repairers and their repair behaviours to extend product lifetimes. We conducted a structured and systematic review of published work (n = 183) to identify the conceptual content of the field to inform our theorization. Our findings highlight three key issues. First, constricted theorization undermines understanding of self‐repairers and their product lifetime extension (and spillover) behaviours. Second, the underlying conceptual complexity is typically underestimated. Third, the dominance of voluntarist and deterministic studies impedes new directions in research. From our review, an integrated worldview–personhood framework emerges that can deepen understanding of avant‐garde self‐repairers’ engagement with product lifetimes.

Design of hole transport type host for stable operation in blue organic light-emitting diodes

Molecular design of the hole transport type host for mixed host was investigated to improve the lifetime of the phosphorescent organic light-emitting diodes. A negative polaron stabilizing hole transport type host design was employed and the effect of the negative polaron stabilizing unit was investigated. Dibenzofuran or benzonitrile was introduced as the negative polaron stabilizing unit in the bicarbazole backbone structure of the hole transport type host. Two host materials were synthesized and the comparison of them proposed that the negative polaron stabilizing unit is a key to the lifetime of the phosphorescent organic light-emitting diodes. The dibenzofuran and benzonitrile embedded bicarbazole hosts performed better than the mCBP host. The dibenzofuran and benzonitrile modified bicarbazole hosts demonstrated high external quantum efficiency of 18.6 and 19.1%, respectively and lifetime extension by 30% compared with the conventional host without the negative polaron stabilizing unit.