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Moreover, the growth of dark spots is strongly suppressed in the sample OLED and the device lifetime is extended considerably. It is shown that an OLED sample with a polyimide‐copolymer interlayer exhibits high peak brightness of nearly 96 000 cd m⁻² and efficiency of ≈92 cd A⁻¹, much higher than those (≈73 000 cd m⁻² and ≈83 cd A⁻¹) of a well‐organized reference OLED.
![hdt physics extension stretching hdt physics extension stretching](http://i762.photobucket.com/albums/xx266/bio-nuke/skyrim/2014-06-08_00003.jpg)
Herein, a novel functional interlayer consisting of a poly(amic acid)‐polyimide copolymer is introduced for use in OLEDs. Finally, we suggest a set of recommended practices and a checklist for device characterizations, aiming to help the researchers in the QLED field to achieve accurate and reliable measurements.Įnsuring the long‐term stability of high‐performance organic light‐emitting diodes (OLEDs) has remained a great challenge due to their limited lifetime and durability. Larger errors in the operational-lifetime measurements may arise from the inaccurate determination of the initial luminance and inconsistent methods for analyzing the luminance-decay curves. We show that the emission non-uniformity across the active area, non-Lambertian angular distributions of EL intensity, and discrepancies in the adopted spectral luminous efficiency functions could introduce significant errors in the device efficiency. Here, we report a comprehensive study on the characterizations of QLEDs using various methods. Despite the encouraging advances in the mechanism investigation, material chemistry, and device engineering of QLEDs, the lack of standard protocols for the characterization of QLEDs may cause inaccurate measurements of device parameters and invalid comparison of different devices. Quantum dot light-emitting diodes (QLEDs) are a class of high-performance solution-processed electroluminescent (EL) devices highly attractive for next-generation display applications. We thus further passivate this key interface, which results in a high external quantum efficiency of 22.8% and obviously improved operational stability. These findings indicate that one of the dominant degradation pathways in PeLEDs is the generation of halide vacancies at perovskite/hole transport layer interface during operation.
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We find that the accumulated halides within the hole transport layer undergo back-diffusion toward the surface of the perovskite layer during resting, repairing the vacancies and thus resulting in electroluminescence recovery. Here, we report a unique self-repairing behavior that the electroluminescence of moderately degraded PeLEDs can almost completely restore to their initial performance after resting. Although field-dependent ion migration is believed to play an important role in the operation of perovskite optoelectronic devices, a complete understanding of how it affects the stability of PeLEDs is still missing. One of the most critical challenges in perovskite light-emitting diodes (PeLEDs) lies in poor operational stability. We then use our model to fit all the experimental data measured under different driving condition, and show that by carefully fitting the accelerated luminance lifetime-curves, we can extrapolate the low-luminance lifetime needed for real display applications, with a high degree of accuracy. Furthermore, we will demonstrate that the main relaxation event is the annihilation of one emissive center. By using an approach based on local relaxation events, we will demonstrate that a single mechanism is responsible for the dominant aging process.
Hdt physics extension stretching free#
In this way, we are able to prove that they can all be described by employing a single free parameter model. We first show that a stretched exponential decay can be used to fit almost all the luminance versus time curves obtained under different driving conditions. In this paper, we propose an approach to describe the intrinsic mechanisms involved in the OLED aging. The main process responsible for the luminance degradation in organic light-emitting diodes (OLEDs) driven under constant current has not yet been identified.