Section 2 Display Technology

*Liquid Crystals and Display Technology*

DOI: 10.1039/C8NR07385F

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[48] Kanno K, Koike N, Korai Y, et al. Mesophase pitch and phenolic resin blends as binders for magnesia-graphite bricks. Carbon. 1999;**37**(2):195-201. DOI: 10.1016/S0008-6223(98)00152-3

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carbon.2010.12.046

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**123**

**Chapter 5**

**Abstract**

photodetector

**1. Introduction**

Photodetector

*Wim Dehaene and Kris Myny*

applications such as finger and palmprint sensing.

AMOLED Displays with In-Pixel

*Nikolaos Papadopoulos, Pawel Malinowski, Lynn Verschueren,* 

The focus of this chapter is to consider additional functionalities beyond the regular display function of an active matrix organic light-emitting diode (AMOLED) display. We will discuss how to improve the resolution of the array with OLED lithography pushing to AR/VR standards. Also, the chapter will give an insight into pixel design and layout with a strong focus on high resolution, enabling open areas in pixels for additional functionalities. An example of such additional functionalities would be to include a photodetector in pixel, requiring the need to include in-panel TFT readout at the peripherals of the full-display sensor array for

**Keywords:** AR, VR, OLED, readout, TFT, high resolution, extra functionalities, fingerprint, additional, functionalities, lithography, in-panel, high resolution,

Active matrix OLED (AMOLED) displays are today's mainstream consumer displays available in various form factors, such as smart watches, mobile displays, and large area television. They are highly appealing because of their wide viewing angles, nice color saturation and great potential for curved, flexible and/or rollable format. There are several options for (flexible) backplane technologies based on thin-film transistors (TFTs), namely, metal-oxide TFTs (such as indium gallium zinc oxide or IGZO), low-temperature polycrystalline silicon (LTPS) TFTs, or a combination of IGZO and LTPS, more precisely LTPO or low-temperature polycrystalline silicon and metal oxide. All these technologies have their pros and cons. Among others, IGZO semiconductors are n-type only which is sufficient for a backplane driving an OLED but is less adequate for peripheral circuits. Another key important asset of IGZO is the ultralow source-drain leakage current due to the large bandgap of the semiconductor, enabling long retention times of data storing, i.e., pixels are not leaking. In contrary, LTPS has both n- and p-type devices and thus the capability of CMOS circuits. LTPS transistors can drive larger currents due to the intrinsically higher mobility, enabling complex in-pixel compensation schemes and peripheral circuits. However, with LTPS transistors the leakage will be larger. This is a key reason why LTPO has been developed: this technology combines

*Tung Huei Ke, Auke Jisk Kronemeijer, Jan Genoe,* 
