Color-Filter-Free Three-Layer-Stacked Image Sensor Using Blue/Green-Selective Organic Photoconductive Films with Thin-Film Transistor Circuits on CMOS Image Sensors
Toshikatsu Sakai, Tomomi Takagi, Koki Imamura, Keitada Mineo, Hidenori Yakushiji, Yuta Hashimoto, Tatsuya Aotake, Yuichi Sadamitsu, Hiroto Sato, Satoshi Aihara
Abstract
In this paper, we describe a three-layer-stacked color image sensor comprising two organic photoconductive films (OPFs) with thin-film transistor-based readout circuits and a complementary metal–oxide–semiconductor (CMOS) image sensor. In this three-layer-stacked sensor, a blue-sensitive OPF selectively absorbs blue light, a green-sensitive OPF selectively absorbs green light, and a CMOS image sensor (CIS) receives red light. Color video imaging operation at 60 frames per second was confirmed for a prototype sensor having 320 × 240 pixels with a pixel pitch of 20 μm without a color filter array, and good color separation and a linear response of the sensor were achieved owing to the combination of the CIS and color-selective OPFs.