Fabrication of Image Sensor Pixel Using Liquid Crystalline Organic Semiconductors

Abstract

In this study, image sensor pixels were fabricated on PET (polyethylene terephthalate) films by integrating organic transistors using liquid crystalline organic semiconductor Ph-BTBT-10 and organic photodetector using liquid crystalline phthalocyanine derivatives 8H₂Pc. Also, we used photo cross-linkable polymer poly (vinyl cinnamate) as patternable gate insulator of organic transistors. The fabricated image sensor pixels were confirmed to exhibit pixel switching by the transistors. The linear dynamic range was 51 dB, and the pixel exhibited a highly linear photo-current response between light irradiation of 10 nW/cm²and 100 µW/cm², where the resistance of ON state transistor is smaller than that of the photodetector. Below light irradiation of 10 nW/cm², output current was limited by dark current of photodetector. 2.6 ms response time was achieved and it is an operating speed of 12 rows of output per frame at 30 fps.