Organic Flexible Electronics

Atomic layer deposition (ALD) has been receiving more and more research attention in the past few decades, ascribed to its unrivaled capabilities in controlling material growth with atomic precision, manipulating novel nanostructures, tuning material composition, offering multiple choices in terms of crystallinity, and producing conformal and uniform film coverage, as well as its suitability for thermally sensitive substrates. These unique characteristics have made ALD an irreplaceable tool and research approach for numerous applications. In this review, we summarize the recent advances of ALD in several important areas including rechargeable secondary batteries, fuel cells, solar cells, and optoelectronics. With this review, we expect to exhibit ALD's versatile potential in providing unique solutions to various technical challenges and also hope to further expand ALD's applications in emerging areas.

Atomic layer deposition for nanomaterial synthesis and functionalization in energy technology

Organic light emitting diodes (OLEDs) have been well known for their potential usage in the lighting and display industry. The device efficiency and lifetime have improved considerably in the last three decades. However, for commercial applications, operational lifetime still lies as one of the looming challenges. In this review paper, an in-depth description of the various factors which affect OLED lifetime, and the related solutions is attempted to be consolidated. Notably, all the known intrinsic and extrinsic degradation phenomena and failure mechanisms, which include the presence of dark spot, high heat during device operation, substrate fracture, downgrading luminance, moisture attack, oxidation, corrosion, electron induced migrations, photochemical degradation, electrochemical degradation, electric breakdown, thermomechanical failures, thermal breakdown/degradation, and presence of impurities within the materials and evaporator chamber are reviewed. Light is also shed on the materials and device structures which are developed in order to obtain along with developed materials and device structures to obtain stable devices. It is believed that the theme of this report, summarizing the knowledge of mechanisms allied with OLED degradation, would be contributory in developing better-quality OLED materials and, accordingly, longer lifespan devices.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/advs.202002254

Approaches for Long Lifetime Organic Light Emitting Diodes.

This project seeks to extend the lifetime of organic light-emitting devices (OLEDs) by blocking the transmission of ambient oxygen and moisture into the delicate emissive region of the device. Our approach is to encapsulate the organic device with hybrid thin-film stacks of both organic and inorganic materials. It is projected that, for commercial applications, such an encapsulation scheme will need to reduce the water vapor transmission to 1 x10 -6 g/m 2 -day and the oxygen transmission to 1 x10 -5 cm 3 (STP)/m 2 -day. We have developed a low-temperature (100oC) PECVD (ltPECVD) process for both amorphous silicon nitride and amorphous silicon oxide layers which yield optically transparent layers (>85% transmission) with low stress (-1.6 x10 9

Thin-Film Encapsulation of Organic Light-Emitting Devices

Recent trends in thin film encapsulations (TFEs), fabricating organic/inorganic encapsulation films are reviewed. Atomic layer deposited inorganic films have superior barrier performance and have advantages of excellent uniformity over large scales at relatively low deposition temperatures. However, organic film should be combined with a hybrid structure for improved flexibility and longer lag time. We introduce various organic deposition methods and mechanisms for enhancing barrier performance. However, stress engineering is required to achieve high performance TFEs for flexible devices, new materials and deposition methods.
 First, modulating the internal stress in TFEs should be considered to increase flexibility by adopting other layers that can reduce internal stress. Second, controlling the configuration of the hybrid structure can prevent degradation due to cracks. Third, the introduction of a neutral plane as the middle layer decreases the strain. The results summarize how the device can improve barrier performance under external stress. This paper can guide the improvements in barrier performance.

Review of Organic/Inorganic Thin Film Encapsulation by Atomic Layer Deposition for a Flexible OLED Display

A hybrid nanolaminates consisting of Al2O3/ZrO2/alucone (aluminum alkoxides with carbon-containing backbones) grown by atomic layer deposition (ALD) were reported for an encapsulation of organic light-emitting diodes (OLEDs). The electrical Ca test in this study was designed to measure the water vapor transmission rate (WVTR) of nanolaminates. We found that moisture barrier performance was improved with the increasing of the number of dyads (Al2O3/ZrO2/alucone) and the WVTR reached 8.5 × 10−5 g/m2/day at 25°C, relative humidity (RH) 85%. The half lifetime of a green OLED with the initial luminance of 1,500 cd/m2 reached 350 h using three pairs of the Al2O3 (15 nm)/ZrO2 (15 nm)/alucone (80 nm) as encapsulation layers.

/pdf/thin-film-encapsulation-for-organic-light-emitting-diodes-222o137xx0.pdf

Thin film encapsulation for organic light-emitting diodes using inorganic/organic hybrid layers by atomic layer deposition.

Growth of IZO/IGZO dual-active-layer for low-voltage-drive and high-mobility thin film transistors based on an ALD grown Al2O3 gate insulator

ZrO2 insulator modified by a thin Al2O3 film to enhance the performance of InGaZnO thin-film transistor

Sunlight-like white organic light-emitting diodes with inorganic/organic nanolaminate distributed Bragg reflector (DBR) anode microcavity by using atomic layer deposition

He Ding

Papers

Thin film encapsulation for organic light-emitting diodes using inorganic/organic hybrid layers by atomic layer deposition.

Growth of IZO/IGZO dual-active-layer for low-voltage-drive and high-mobility thin film transistors based on an ALD grown Al2O3 gate insulator

ZrO2 insulator modified by a thin Al2O3 film to enhance the performance of InGaZnO thin-film transistor

Sunlight-like white organic light-emitting diodes with inorganic/organic nanolaminate distributed Bragg reflector (DBR) anode microcavity by using atomic layer deposition

Effect of gate insulator thickness on device performance of InGaZnO thin-film transistors