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Background Right ventricular outflow tract obstruction (RVOTO) is a cause of hemodynamic instability that can occur in several situations, including cardiac surgery, lung transplantation, and thoracic surgery, and in critically ill patients. The timely diagnosis of RVOTO is important because it requires specific considerations, including the adverse effects of positive inotropes, and depending on the etiology, the requirement for urgent surgical intervention. Methods The objective of this systematic review and meta-analysis was to determine the prevalence of RVOTO in adult patients, and the distribution of all reported cases by etiology. Results Of 233 available reports, there were 229 case reports or series, and 4 retrospective cohort studies, with one study also reporting a prospective cohort. Of 291 reported cases of RVOTO, 61 (21%) were congenital, 56 (19%) were iatrogenic, and 174 (60%) were neither congenital nor iatrogenic (including intracardiac tumour). The mechanism of RVOTO was an intrinsic obstruction in 169 cases (58%), and an extrinsic obstruction in 122 cases (42%). A mechanical obstruction causing RVOTO was present in 262 cases (90%), and 29 cases of dynamic RVOTO (10%) were reported. In the 5 included cohorts, with a total of 1122 patients, the overall prevalence was estimated to be 4.0% (1%-9%). Conclusions RVOTO, though rare, remains clinically important, and therefore, multicentre studies are warranted to better understand the prevalence, causes, and consequences of RVOTO., Graphical Abstract Image, graphical abstract

Supplemental Digital Content is available in the text., Right ventricular outflow tract obstruction (RVOTO) is a rare cause of hemodynamic instability in the intensive care unit (ICU) after cardiac surgery. We report the first cases of RVOTO diagnosed in the ICU using continuous right ventricular pressure waveform monitoring. Our 2 cases reflect both mechanical and dynamic causes of obstruction, each of which require different approaches to treatment. Inotrope use can exacerbate RVOTO caused by dynamic etiology, whereas surgery is usually the treatment of choice for mechanical obstructions. Inability to recognize RVOTO or the correct etiology can lead to hemodynamic compromise and poor outcomes.

A dithienylethene molecule involving carborane clusters shows remarkable fatigue resistance and high contrast visual colour changes when irradiated with alternating ultraviolet and visible light. The fluorescence of this assembly can be switched on and off when irradiated in the solid state but not in the solution state.

High-performance low-k and low-loss circuit materials are urgently needed in the field of microelectronics due to the upcoming Fifth-Generation Mobile Communications Technology (5G Technology). Herein, a facile design strategy for non-fluorinated intrinsic low-k and low-loss polyimides is reported by fully considering the secondary relaxation behaviors of the polymer chains. A new amorphous non-fluorinated polymer (TmBPPA) with a k value of 2.23 and a loss tangent lower than 3.94 × 10−3 at 104 Hz has been designed and synthesized, which to the best of our knowledge is the lowest value amongst the non-fluorinated and non-porous polymers reported in literature. Meanwhile, TmBPPA exhibits excellent overall properties, such as excellent thermostability, good mechanical properties, low moisture absorption, and high bonding strength. As high-performance flexible circuit materials, all these characteristics are highly expected to meet the present and future demands for high density, high speed, and high frequency electronic circuit used in 5G wireless networks.

Prolonging the phosphorescence lifetime of pure organic phosphorescent materials by a methyl-substitution strategy is described. We present a chemical strategy for improving the phosphorescence lifetime of triplet excitons under ambient conditions by incorporating methyl groups into the chemical structures. This is observed by a long-lived phosphorescence lifetime of up to 0.83 s detected for methylated 9-(4-(mesitylsulfonyl)phenyl)-9H-carbazole (3M), compared to 0.36 s for 9-(4-(phenylsulfonyl)phenyl)-9H-carbazole (0M) without any methyl groups. Additionally, enhanced phosphorescence efficiency can be obtained at an appropriate methylation degree, because of the smaller ΔEST (singlet and triplet energy gap) and ΔETT* (normal phosphorescence and long-lived phosphorescence energy gap). A comprehensive investigation on the packing mode in the crystalline state reveals that the methyl groups occupy the free volume and result in a suppression of non-radiative decay, accounting for the enhanced phosphorescence lifetime.

Supplemental Digital Content is available in the text., Objectives: To report the use of common femoral vein Doppler interrogation as a simple technique to diagnose right ventricular dysfunction. Design: Case report. Setting: Cardiac surgical ICU. Patients: Postoperative cardiac surgical patients. Interventions: Common femoral pulsed-wave and color Doppler examination associated with hepatic, portal, and renal venous Doppler measurement were obtained in both patients and before and after treatment in patient number 1. In addition, right ventricular pressure waveform examination was obtained in patient number 2. Measurements and Main Results: The technique to obtain common femoral venous Doppler is described. Two cases of patients presenting with right ventricular dysfunction and fluid overload with portal and renal venous congestion in the perioperative period undergoing complex multivalvular cardiac surgery are presented. Hemodynamic waveform monitoring was performed alongside echocardiographic, hepatic, and renal venous flow Doppler assessment, and spectral Doppler profiles of the common femoral veins were examined. Those findings were useful in confirming our diagnosis and guiding our response to treatment. An algorithm was developed and tested on two additional hemodynamically unstable patients. Conclusions: Doppler examination of the common femoral vein is a simple, fast, and noninvasive technique that could be useful to rule in the presence of right ventricular dysfunction with venous congestion and help guide the management of such patients.

The persistent room-temperature phosphorescence (RTP) of purely organic materials in the solid state has recently attracted much research interest and found promising, rapid and visual applications by the naked eye, after the removal of the excitation source. However, almost all reported organic persistent RTP processes are induced by using a UV-light irradiation source. In this report, persistent RTP with an emission lifetime as long as 0.15 s which can be induced not only by photoirradiation but also by mechanical action is presented, which merges mechano-induced luminescence and persistent RTP together. It is found that such persistent RTP is produced through intermolecular electronic coupling (IEC) of units with different excited state configurations. Interestingly, there are two different crystals with and without mechano-induced persistent RTP which can be grown from this organic material, as such a new type of mechano-luminescence (ML) is strongly dependent on their intermolecular interactions. Furthermore, the intensity of such mechano-induced persistent RTP can be increased by lowing the temperature as well, similar to that of photo-induced persistent RTP. Notably, these two crystals exhibit a ML enhancement and ML “turn on”, respectively, with decreasing temperature. Therefore, such mechano-induced persistent RTP provides an example of new types of organic luminescent materials, which is a missing jigsaw piece of organic luminescence and important for both fundamental research and practical applications of both persistent RTP and ML of organic materials.

This study provides a reliable strategy to tune the mechanoluminescent colors by adjusting the weak intermolecular interactions., A new mechanoluminescent material (4-(diphenylamino)phenyl)(4-(diphenylphosphanyl)phenyl)methanone (CDpP), which displays tunable mechanoluminescent emission colors, has been designed and successfully synthesized. CDpP shows two distinct mechanoluminescent colors (blue and green) in different crystalline states. Single-crystal analyses and femtosecond transient emission studies reveal that the striking tunable mechanoluminescence properties of CDpP mainly originate from the different C–H···π interactions in the crystal structures. CDpP crystals with more C–H···π interactions show blue mechanoluminescence (ML), and the emission is attributed to the locally excited (LE)-state because the twisting process for the excited state is restricted by C–H···π interactions. Conversely, CDpP crystals with fewer C–H···π interactions display green ML, in which the red-shifted emission band originates from the twisted intramolecular charge transfer (TICT) excited state because the diphenylamine moiety is relatively free to rotate. The manipulation of weak intermolecular interactions in the crystalline state is a useful and reliable strategy for the tuning of the ML emission wavelengths.

Flexible hydrogen-bonded organic frameworks (FHOFs) are quite rare but promising for applications in separation, sensing and host-guest chemistry. They are difficult to stabilize, making their constructions a major challenge. Here, a flexible HOF (named 8PN) with permanent porosity has been successfully constructed. Nine single crystals of 8PN with different pore structures are obtained, achieving a large-scale void regulation from 4.4% to 33.2% of total cell volume. In response to external stimuli, multimode reversible structural transformations of 8PN accompanied by changes in luminescence properties have been realized. Furthermore, a series of high-quality co-crystals containing guests of varying shapes, sizes, aggregation states and even amounts are obtained, showing that 8PN can adapt to different guests by regulating the molecular conformations and assembling forms of its building blocks. The unexpected flexibility of 8PN makes it a promising material for enriching the applications of existing porous materials., Flexible hydrogen-bonded organic frameworks (FHOFs) are challenging in fabrication but promising materials for applications in separation and sensing. Here, the authors report a stimuli responsive and flexible HOF which can adapt to different guests by regulating the molecular conformation.

Small energy gap boosts dual-channel triplet harvesting via TADF and UOP, which suppresses long-lived triplet concentration quenching. An infrared laser (808 nm) is able to induce persistent emission under ambient conditions., Due to inefficient molecular design strategies, two-photon-excited ultralong organic room temperature phosphorescence (TPUOP) has not yet been reported in single-component materials. Herein, we present an innovative design method by dual-channel triplet harvesting to obtain the first bright TPUOP molecule with a lifetime of 0.84 s and a quantum efficiency of 16.6%. In compound o-Cz the donor and acceptor units are connected at the ortho position of benzophenone, showing intramolecular space charge transfer. Therefore, the two-photon absorption ability is improved due to the enhanced charge transfer character. Moreover, the small energy gap boosts dual-channel triplet harvesting via ultralong thermally activated delayed fluorescence and H-aggregation phosphorescence, which suppresses the long-lived triplet concentration quenching. Through two-photon absorption, a near-infrared laser (808 nm) is able to trigger the obvious ultralong emission under ambient conditions. This research work provides valuable guidance for designing near-infrared-excited ultralong organic room temperature phosphorescence materials.

An ortho-substituent design strategy promoting steric hindrance has afforded excellent AIE-TADF emitters, and high-efficiency TADF-OLEDs have been subsequently demonstrated., Thermally activated delayed fluorescence (TADF) materials have opened a new chapter for high-efficiency and low-cost organic light-emitting diodes (OLEDs). Herein, we describe a novel and effective design strategy for TADF emitters which includes introducing a carbazole donor unit at the ortho-position, at which the donor and acceptor groups are spatially in close proximity to guarantee the existence of intramolecular electrostatic attraction and through-space charge transfer, leading to reduced structural vibrations, suppressed non-radiative decay and rapid radiative decay to avoid excited state energy loss. As a result, a green TADF emitter (2Cz-DPS) showing high solid-state photoluminescence quantum efficiency (91.9%) and excellent OLED performance was produced. Theoretical simulations reveal that the non-adiabatic coupling accelerates the reverse intersystem crossing of 2Cz-DPS, resulting in a state-of-the-art non-doped OLED with an extremely high external quantum efficiency of 28.7%.

A general approach for the synthesis of dibenzofulvene-based derivatives is demonstrated. The bisanthracene modified dibenzofulvene (F-DAn) exhibits efficient piezofluorochromic properties with the fluorescence reversibly altered between green (536 nm) and red (620 nm) under external stimuli.

Two heavy atom-free white-light emitting luminophores exhibit fluorescence–phosphorescence dual-emission and are multi-stimuli responsive at room temperature., Two heavy atom-free luminophores (SHB2t and SDB2t) with simple molecular structures have been synthesized via Suzuki coupling reactions in which both display white-light emission with prompt fluorescence and room temperature phosphorescence (RTP) in the solid state. The impressive RTP of the luminophores is produced by a synergistic effect of the strong intermolecular hydrogen bonding in addition to the spin–orbit coupling of the sulfonyl oxygen atoms and the moderate singlet-triplet energy gaps (ΔE ST). These factors facilitate the intersystem crossing (ISC) process to generate triplet excitons in which the molecular conformations become immobilized to effectively suppress radiationless decay. Under the stimuli of mechanical force and solvent vapor, the RTP of SHB2t and SDB2t can be simply turned off and on by breaking and reforming the robust hydrogen bonding, which leads to remarkable and reversible mechanochromism between white and deep-blue emission. Moreover, two different thermochromic processes have been observed for the pristine and ground samples of SDB2t, in which a tricolor switching system between white, deep-blue and blue emission has been successfully achieved through the sequential control of grinding, heating and fuming. From detailed studies we have determined that the mechanism for the thermochromism of SDB2t is correlated with the rearrangement of the white-light emitting molecules to a new packing mode without RTP emission.

Photosensitive fluorescent probes have become powerful tools in chemical biology and molecular biophysics, which are used to investigate cellular processes with high temporal and spatial resolution. Accordingly, photosensitive fluorescent probes, including photoactivatable, photoconvertible, and photoswitchable fluorophores, have been extensively developed during the past decade. The photoswitchable fluorophores have received much attention because they highlight cellular events clearly. This minireview summarizes recent advances of using reversibly photoswitchable fluorophores and their applications in innovative bioimaging. Photoswitchable fluorophores include photoswitchable fluorescent proteins, photoswitchable fluorescent organic molecules (dyes), and photoswitchable fluorescent nanoparticles. Several strategies have been developed to synthesize photoswitchable fluorophores, including engineering combination proteins, chemical synthesis, polymerization, and self-assembly. Here we concentrate on polymer nanoparticles with optically switchable emission properties: either fluorescence on/off or dual-alternating-color fluorescence photoswitching. The essential mechanisms of fluorescence photoswitching enable different types of photoswitchable fluorophores to change emission intensity or wavelength (color) and thus validating the basis of the fluorescence on/off or dual-color photoswitching design. Generally the possible applications of any fluorophores are to label biological targets, followed by specific imaging. The newly developed photoswitchable fluorophores enable super-resolution fluorescence imaging because of their photosensitive emission. Finally, we summarize the important area regarding future research and development on photoswitchable fluorescent nanoparticles.

Liquid-crystal (LC) gels are normally used as insulating, scattering media in LC displays. Organic solar cells generate electrical power by the separation of photocreated electrons and holes at the interface between electron-donating and electron-accepting organic semiconductors. We combine these two technologies to create a new type of plastic solar cell. The efficiency of solar cells can be improved by enlarging the interface area to maximize charge separation and by vertically separating the two materials to provide different paths for electrons and holes to the electrodes. We use a new electron-donating, visible-light absorbing, LC gel to form a surface with nanometer-sized grooves with a large interface area to an overlying electron-accepting layer. This forms a photovoltaic cell, which exhibits a monochromatic power conversion efficiency of 0.6 % at an incident intensity of 45 mW cm. Improvements will provide low-cost, robust solar cells compatible with plastic electronics and roll-to-roll processing. Most organic photovoltaics use either main-chain conjugated polymers, often in conjunction with fullerenes, or low-molecular-weight glasses, achieving power-conversion efficiencies up to 4.2 %. Charge separation is achieved in solar cells by ionization of the photogenerated exciton at a heterointerface between electron-donating material with a low ionization potential (IP) and electron-accepting species with a high electron affinity (EA). The diffusion length of the exciton before recombination is of the order of 100–200 A, so that distributed, rather than planar, heterointerfaces have been used to maximize charge separation. These have been formed by phase-separated blends of electron-donating and electronaccepting organic materials. The bulk-distributed heterojunctions are formed randomly and do not guarantee a continuous pathway for charge carriers to the electrodes. The required vertical segregation of the blend materials can be obtained by surface treatment or in diffuse bilayer photovoltaics. A blend of an electron-donating columnar LC, hexabenzocoronene, and an electron-accepting perylene dye vertically segregates spontaneously to give an efficient photovoltaic effect. Unfortunately, the spatial scale of the phase separation cannot be controlled reproducibly in these devices. Another problem for phase-separated configurations is poor stability of the domain size lowering the device efficiency. To date the photovoltaic effect has only been demonstrated with calamitic LCs via an ionic mechanism, although electronic photoconductivity has been well researched. Polymerizable LCs, with two polymerizable groups attached through flexible aliphatic spacers to an aromatic core, are attracting interest as organic semiconductors for electroluminescence and organic transistors. Their advantages include spontaneous self-assembly, relatively high charge mobility (1 × 10 cm V s), easy deposition by spin-coating or ink-jet printing and lithographic photopatterning to form multilayer polymer networks. We now report the use of reactive mesogens in a novel way to demonstrate a new approach to photovoltaics. Liquid-crystalline gels are formed from a homogeneous mixture of a reactive mesogen and a non-polymerizable LC. Polymerization results in controlled phase separation of the two components and the formation of a polymer network matrix around the nematic droplets. To date, transparent LC gels have typically been used in direct-view reflective displays, switchable polarizers, directional reflectors, and so forth. Polymerization-induced phase separation of a homogeneous mixture of a LC and a polymer-forming material brings the concept of a paintable display closer. A key step in our new approach is the use of mixtures of hole-transporting reactive mesogens with a low IP and analogous LCs with the same aromatic core to form an electron-donating LC gel. An ideal LC composite photovoltaic is illustrated in Figure 1. It has a vertically separated, large-area interface between electron-donating and electron-accepting layers providing complete pathways for transport of holes and electrons. An electron-blocking polymer network of the electron-donating reactive mesogen is deposited first on an electrode surface by spin-coating from solution and then crosslinking in order to provide a high open circuit. A mixture of the same electron-donating reactive mesogen and the corresponding non-polymerizable analogue are then deposited in a similar C O M M U N IC A TI O N S

We report the synthesis of a red light‐emitting and photopolymerizable smectic liquid crystal (reactive mesogen). We investigate the suitability of polymer networks formed from smectic reactive mesogens for use in organic light‐emitting diodes (OLEDs). The use of mixtures of smectic reactive mesogens is shown to lower the processing temperature for the fabrication of OLEDs to room temperature. We also report efficient energy transfer from a nematic polymer network host to a smectic light‐emitting dopant and polarized emission from a polymer network formed from an aligned smectic reactive mesogen.

Exploring the viral infection mechanism is important for preventing and controlling viral diseases and rationally designing antiviral drugs. Single-particle tracking (SPT) is a powerful technique for revealing real-time and in-situ dynamics of single-virus events in live cells. However, most of previously reported tags for single-virus tracking have low labeling efficiency and photoinstability, unfavorable to imaging. We have developed a single-virion labeling strategy based on quantum dots (QDs), which possess exceptional photostability and high fluorescence brightness, allowing to track biomolecules over unprecedented durations with a high signal-to-noise ratio. This strategy could achieve nearly total labeling of all influenza virions with QDs. Accordingly, we developed a QDs-based SPT technique to efficiently and globally investigate virus infection behaviors in individual cells. The technique can be used to unravel virus infection and solve some pending problems, such as how influenza viruses move and interact with late endosomes in host cells. For better understanding of virus infection, we developed a new single-particle localization algorithm for QDs-based tracking of individual virions in three dimensions (3D). A rapid and subpixel-accuracy algorithm for 3D localization has been proposed. The computing speed is as fast as that of the centroid method, and the computing accuracy is as good as that of Gaussian fitting method. These are very meaningful for accurately and rapidly processing massive 3D image data. The mechanism of virus infection is being studied by 3D imaging using QDs with excellent optical properties. Overall, the techniques developed in our lab are expected to be widely used for globally studying the transport behaviors of viruses at the molecular level to unravel their infection mechanism.

Grazing incidence X-ray diffraction is used to find the thin film morphology of an extended molecule with an irregular alternating fluorene-thiophene structure, which is used to obtain linearly polarized electroluminescence and the photovoltaic effect. The material has a room temperature nematic glassy phase and is uniaxially aligned in the plane of the film using photoalignment techniques. Two distinct intermolecular separations of 0.45 and 1.5 nm are identified showing that the molecules are lamellar. The lamellae stack with only local order and the two short axes of the lamellae have no preferred orientation at the surface or bulk of the film. Neighboring molecules show a wide range of longitudinal displacements along the axis of the director, as expected for a nematic liquid crystal with no positional order. There is, however, a dominant feature corresponding to a longitudinal offset of 0.51 nm. Unlike some other fluorene-containing semiconductors where microphase separation of the side chains inhibits close packing of neighboring molecules, the lamellar structure and 0.45 intermolecular spacing found here allows pi-pi intermolecular interactions for efficient carrier transport. We obtain a room temperature hole mobility up to 3.4 x 10-3 cm2 V-1 s-1 using a time-of-flight technique.

Photoinduced absorption shows that triplets are the primary photoexcited species in a series of conjugated liquid crystals containing thiophene and fluorene groups. We find that the triplet generation rate can be varied substantially by molecular design. The introduction of extra thiophene groups into the elongated molecules changes the intersystem crossing rate by over two orders of magnitude, while modifying the singlet and triplet energies by only small amounts. This result is attributed to the high spin-orbit coupling constant of sulfur: An increase in the number of sulfur atoms increases the spin-orbit coupling between the singlet and triplet states. These results are relevant to the design of organic light emitting diodes, lasers, and other devices where triplet formation has a major impact on device performance. The molecules are shown to act as effective electron donors when blended with a perylene molecule which acts as an electron acceptor. The electron transfer rate is faster than the singlet lifetime so that the blend shows the efficient charge separation required for a photovoltaic device.

We discuss a liquid crystal composite approach to provide a distributed interface to vertically separate electron-donating and electron-accepting films in an organic photovoltaic device. Two differ...

Blue, green, and red polymerizable light-emitting liquid crystals have been patterned photolithographically in a full-color liquid-crystal electroluminescent display. A new hole-transporting photoalignment copolymer is also reported and the spatial patterning of the polarization direction of emission is demonstrated.

Novel heterocyclic and photopolymerizable liquid crystalline materials (reactive mesogens) with smectic phases have been synthesized and characterized. A selection of heterocyclic rings, such as benzothiazole, benzothiadiazole and pyrimidine, has been incorporated into the aromatic core to control the electrochemical/luminescence properties and the structural geometry. Particular emphasis is focused on structure–property relationships, in which the variation of molecular structure and its subsequent effect on the liquid crystalline transition temperatures have been investigated.

We describe the synthesis and characterisation of a novel hole transporting photoalignment copolymer for linearly polarised emission. The copolymer has a coumarin side-chain which undergoes (2 + 2) cycloaddition on irradiation with ultraviolet light. A fluorene side-chain, whose ionisation potential is well matched to the work-function of indium tin oxide, provides hole transporting properties. Polarised green electroluminescence was obtained by spin coating a novel polymerisable and light-emitting liquid crystal onto the photoaligned copolymer. A polarisation ratio value of 13 : 1 and a polarised irradiance of 200 cd m−2 was obtained at 9 V. Polarised red emission is also described in a guest–host configuration. The spatial patterning of the polarisation direction is also shown.

We report the synthesis of photoreactive and light-emitting liquid crystals which can be patterned photolithographically to form polymer networks for use in organic light-emitting diodes. The resolution capability of the photopatterning is investigated using a phase mask of period one micron to spatially modulate the irradiance of ultraviolet light incident to the monomer thin film. A surface relief grating of the same period and depth 85 nm is formed on exposure and washing. An OLED incorporating a novel green light-emitting liquid-crystal has a luminous efficiency of 4.3 lm W-1 at 100 cd m-2 and gives a luminance of 990 cd m-2 at an operating voltage of 10 V.

We report the design, synthesis and optical properties of a fluorescent HABI-based photochrome, which exhibits high fluorescence quantum yield (ΦF = 25%) and efficient quenching in the dissociated state. Efficient contrast fluorescence switching and good reversibility are also demonstrated. We demonstrate the merits of a non-conjugated design strategy for fluorescent HABIs.

* E-mail: mqzhu@hust.edu.cn Received October 8, 2012; revised December 5, 2012; published online December 20, 2012. Project supported by the National Basic Research Program of China (No. 2013CB922104), the National Natural Science Foundation of China (Nos. 20874025, 21174045), the National Natural Science Foundation of China Research Fellowship for International Young Scientists (No. 21150110141), the China Postdoctoral Science Foundation (No. 20100480065), the Open Program for Beijing National Laboratory for Molecular Sciences (BNLMS) and the Special Financial Grant from the China Postdoctoral Science Foundation (No. 2012T50642). 国家基础研究计划 (No. 2013CB922104)、国家自然科学基金 (Nos. 20874025, 21174045)、国家自然科学基金委外国青年学者研究基金 (No. 21150110141)、中国博士后科学基金(No. 20100480065)和中国博士后特别资助基金(No. 2012T50642)资助项目.

In recent years low molecular weight carbazole-based materials have attracted much interest as hole-transporting and host materials for organic light emitting diode (OLED) applications. Herein we report the tri- and tetra-bromination of carbazole and the subsequent synthesis of novel carbazole oligomers substituted at the 1- and 8-positions. The oligomer series range from mono-carbazole (Cz-1) to quinque-carbazole (Cz-5) and we have carried out a comparative study of their thermal, optical, electrochemical and optoelectronic properties. The glass transition temperature increases as the carbazole core is enlarged (0 °C to 54 °C) and all oligomers exhibit excellent thermal stability with high thermal decomposition temperatures in the range of 442 °C to 494 °C. From optical data and Raman spectroscopy we observe negligible changes in the effective conjugation length as the number of peripheral carbazole units increases. However, the oxidation potential decreases as the number of carbazole units increase, in which Cz-5 exhibits the highest HOMO level (−5.19 eV) compared to other carbazole oligomers in the series. All carbazole materials emit deep blue photoluminescence ranging from 416 to 432 nm in the solid-state. Finally, electrophosphorescence was demonstrated from solution processable guest-host organic light- emitting diodes (OLEDs) fabricated using Cz(2–5) as the host materials with device configuration ITO/PEDOT/Cz1–5 : 10% Ir(mppy)3/TPBi/LiF/Al. The device efficiency decreases from Cz-3 to Cz-5. The best OLED device that incorporates Cz-3 as the host exhibits a turn-on voltage of 2.8 V, maximum brightness of 2310 cd m−2, maximum power efficiency of 33.6 lm W−1, maximum current efficiency 35.5 cd A−1 and EQE of 10.6%.