Analysis of Recoverable Residual Image Characteristics of Flexible Organic Light-Emitting Diode Displays Using Polyimide Substrates

Recoverable residual image characteristics for n- and p-type low-temperature polycrystalline silicon (LTPS) thin-film transistor (TFT)-based organic light-emitting diode (OLED) displays using polyimide substrates were investigated. Unlike OLED displays using glass substrates, the n-type LTPS TFT-bas...

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Bibliographic Details
Published in:IEEE electron device letters 2019-07, Vol.40 (7), p.1108-1111
Main Authors: Hwang, Han Wook, Hong, Seonghwan, Hwang, Sang Soo, Kim, Ki Woo, Ha, Yong Min, Kim, Hyun Jae
Format: Article
Language:English
Subjects:
Brightness
CAD
Charge distribution
Computer aided design
Computer simulation
Displays
Electric fields
Flat panel displays
Glass substrates
Hysteresis
Light emitting diodes
Logic gates
low-temperature polycrystalline silicon (LTPS)
Organic light emitting diodes
organic light-emitting diode (OLED)
polyimide
Polyimides
recoverable residual image
Semiconductor devices
Substrates
Thin film transistors
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Summary:Recoverable residual image characteristics for n- and p-type low-temperature polycrystalline silicon (LTPS) thin-film transistor (TFT)-based organic light-emitting diode (OLED) displays using polyimide substrates were investigated. Unlike OLED displays using glass substrates, the n-type LTPS TFT-based OLED displays using a polyimide substrate showed inferior recoverable residual image characteristics compared to the p-type LTPS TFT-based OLED displays. By the analysis of the brightness relaxation characteristics of the residual image and technology computer-aided design (TCAD) simulations, an additional explanation for the recoverable residual image, related to the substrate, was identified. In the polyimide substrate, internal electric fields vary depending on the operation of the driving TFTs. Particularly, in the n-type LTPS driving TFTs, the direction of electric fields changes dramatically with brightness conditions. This can result in a drastic variation in charge behavior inside the polyimide substrate. Consequently, we found that when using a polyimide substrate rather than a glass substrate, the recoverable residual image characteristics of the OLED displays arise due to both the hysteresis characteristics of the LTPS TFTs and the charge generation and distribution in the polyimide substrate.
ISSN:0741-3106
1558-0563
DOI:10.1109/LED.2019.2914142