Devices stability

However, a phase separation problem in the above two-component system may affect the device stability. To overcome the problem, Mullen and coworkers [322] introduced triphenylamine groups as side chains at the PF backbone. The triphenylamine substituents simultaneously improve the hole-transport properties of PF (facilitating the injection of holes),... 

The performance of OLED devices employing CuPc as a HIL is unstable due to thermally induced HTM crystallization on the CuPc surface [27]. One approach to improve the hole injection and enhance the device stability is to overcoat the CuPc or else to directly deposit... 

For the blue pixel, the standard CIE 1931 color chromaticity coordinates are (0.14-0.16, 0.11-0.15). Since a relatively large band gap is required for blue emitters, the appropriate blue host materials with even larger band gap are needed to optimize the energy transfer requirements. The main challenge in designing the blue emitter or its host is the device stability. 

Oxidized MWCNTs have also been tested in conjunction with solid-state electrolytes [107]. Compared to pristine MWCNTs, the oxidized MWCNTs have a better miscibility with the ionic liquids used in the electrolyte. Overall, a much improved gelforming ability resulted. The latter was clearly reflected in the device performance. In particular, devices with oxidized MWCNTs outperformed those with pristine MWCNTs and the reference devices in terms of photocurrents, Vocs, and efficiencies. Importantly, the device stability was also greatly enhanced when oxidized MWCNTs were implemented - 100 days with a loss of overall efficiency by less than 10 °/o. The authors ascribed the drop in efficiency to phase separation and subsequent leakage of ionic liquids. 

The MOSFET heater is directly driven with this bit stream or optionally, the bit stream can be routed through a low pass filter. Early experiments revealed that driving the heater transistor with the raw bit stream might cause some electromigration due to the large peak currents that occur. The low-pass filter was therefore included to avoid such current peaks in order to enhance the device stability and life time. 

It appears that both the Hitachi and DuPont polyimide films, when cured, significantly impede the drift of sodium ions at normal device operating temperatures. There is, however, evidence that underlying device oxides can be contaminated by sodium and/or moisture or other polar molecules during the application and curing of the polyimide films. Qeaner resins and adequate device stabilization may control this problem. Further work will be required to characterize contamination levels associated with specific aspects of the processing, such as the adhesion promoter and the polyimide resins themselves. 

However, the presence of liquid electrolyte has the problems of leakage, robust sealing, and device stability, thus results in limited commercialization. Quasi-solid-state and solid-state DSSCs based on nonvolatile ionic liquid or organic hole-conducting material/polymer as the electrolyte are, therefore, developed to circumvent the sealing problem. 

The branched polysilanes show a broad emission peak around 450 nm, where the large red shift in the fluorescence spectra is due to the influence of aryl substituents and the introduction of branched points. For (opto)electronic applications, the UV irradiation and thermal stability are crucial to device stability. Branched polysilanes have better thermostability and are more resistant to UV irradiation than are linear polysilanes. 

It is generally well appreciated now that the choice of the right dielectric is crucial for achieving optimum field-effect mobility, device stability and reliability. In the same way as silicon MOS technology owes much to the quality of the Si-Si02 interface, dielectrics for organic FETs have recently received significant attention. 

Polymer light-emitting devices (PLEDs) have attracted considerable interest because of their potential use in portable electronic devices. PLEDs have improved the performance of devices by increasing the device stability and efficiency. Chang and coworkers fabricated an efficient PLED using [Ir(acac)(dbq)2] as the phosphorescent dopant of a pvk matrix layer and bbpo as the electron transport material. Trapping of charge carriers at the [Ir(acac)(dbq)2] dopant sites dominates the EL of the device. This is the first PLED that emits red electrophosphorescence centered at 610 nm, exclusively from the dopant and an EL efficiency of 8.5 cdA (luminance 1287 cdm ) biased at 14.5 mAcm . ... 

Using the bead 14, a rotaxane has been synthesized which contains two 7r-electron-rich moieties, namely biphenol and benzidine [76]. The thread portion 23 of this rotaxane therefore contains two stations upon which the tetracationic bead can potentially reside. For such a device, stability of the bead at its preferred station must be considered. This implies that a large energy difference [>kT) between stations must exist at the operating temperature to prevent dynamic shuttling of the bead between the stations. 

From the practical viewpoint, one of the most significant performances of OLEDs is device stability under continuous operation. Here, we summarize previous reports on durability. 

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