Fingerprint imager based on a-Si:H active-matrix photo-diode arrays

In‐Plane Sensing Opportunities in MicroLED Displays

“…With the advent of microLED displays and their associated free area, another type of fingerprint sensor using optical sensing 22,23 could be integrated into the display, reducing cost and expanding the sensing area. 16…”

Complete Issue

“…With the advent of microLED displays and their associated free area, another type of fingerprint sensor using optical sensing 22,23 could be integrated into the display, reducing cost and expanding the sensing area. 16…”

Integration of large‐area optical imagers for biometric recognition and touch in displays

“…An optical TFT-based fingerprint scanner relies on the spatial measurement of transmitted or reflected light coming from a finger placed on top of the imager area. 6 Due to the topology of the fingerprint with so-called ridges, valleys, minutiae, and sweat pores, the amount of reflected light will vary locally based on the feature present. Since ambient light conditions vary greatly and the transmission of the finger is not uniform, the most consistent optical readout is obtained by measuring the fingerprint in reflection.…”

“…However, besides a high sensitivity, also the dark current of the photodiode (in combination with a low leakage current of the transistor) is a crucial parameter, since it will determine the lower limit of light levels where a clear difference in reflection can be measured. [7][8][9] For our OPD frontplane, we use an active layer with abulk heterojunction morphology, comprising a p-type donor polymer poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'di-2-thienyl-2',1',3'-benzothiadiazole)], PCDTBT and an ntype acceptor molecule [6,6]-phenyl-C61-butyric acid methyl ester, PCBM. 1,10,11 The external quantum efficiency (EQE) and J-V characteristics in light and dark are shown in Figure 2.…”