Full-color Organic Image Sensor Developed With Transparent TFTs

May 26, 2010
Tetsuo Nozawa, Nikkei Electronics
The camcorder equipped with the organic image sensor
The camcorder equipped with the organic image sensor
[Click to enlarge image]
An image taken by the camcorder
An image taken by the camcorder
[Click to enlarge image]
The organic image sensors for each of the RGB colors. From the left, they are for blue, green and red colors, respectively. Their colors are complementary colors for the colors to be taken.
The organic image sensors for each of the RGB colors. From the left, they are for blue, green and red colors, respectively. Their colors are complementary colors for the colors to be taken.
[Click to enlarge image]

NHK (Japan Broadcasting Corp) unveiled some of the exhibits that will be showcased by NHK Science & Technology Research Laboratories (STRL) at OpenHouse 2010, which will take place from May 27 to 30, 2010.

One of them is an organic image sensor, which is a CMOS image sensor made by stacking an organic semiconductor material as a photosensitive layer on a transparent TFT array. The TFT array is transparent because, by making a device for each of the red, green and blue colors and staking devices, it enables to realize an image sensor that is compact and highly-sensitive to each of the colors, NHK said.

The ultimate goal of NHK is to develop an ultra-small camcorder for super high vision (See related article). The company has been developing the organic image sensor for several years, but this is the first time that it has realized a shooting system using RGB color devices stacked together and substantiated the original concept, STRL said.

Specifically, NHK made an image sensor with a resolution of 128 x 96 pixels for each of the RGB colors and installed the sensors in a camcorder so that it can shoot color video. The TFT array was developed based on zinc oxide (ZnO) in collaboration with the Kochi University of Technology.

In fiscal 2008, NHK showed a movie taken by a camcorder equipped with an organic image sensor. But it was made with devices that are for only red and green colors and have a resolution of about 47 x 30 pixels.

"We have just substantiated our principle," NHK said. "From now on, we will start development in the aim of commercialization."

The company plans to develop organic image sensors in 10 years for HD camcorders and in 20 years for super high vision camcorders.