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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.

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We have studied ways of stabilizing the bend configuration in π-cells by forming polymer walls. This novel device with polymer walls, which makes an initial splay-bend transition unnecessary, incorporates minute structures fabricated by applying the processes of local photopolymerization-induced phase separation and electric field orientation. In fabricating the device, a mixed solution of nematic liquid crystal and an ultraviolet (UV)-curable liquid-crystalline monomer was subjected to an electric field to induce the bend transition, and UV light was illuminated on selected regions in this mixed solution to cause photopolymerization, so that minute aligned polymer walls could be selectively formed inside the device. We examined the operation of the device and found that the bend-alignment cells performed basic functions in the stable bend state, and that this state can be maintained even if the cells are set to a small pre-tilt angle, such as 1°.