Color Image Sensor Using Stacked Organic Photoconductive Films with Transparent Readout Circuits Separated by Thin Interlayer Insulator

We have been working on developing an image sensor with three stacked organic photoconductive films (OPFs) sensitive to only one primary color component (red-R, green-G, or blue-B); each OPF has a signal readout circuit. This type of stacked sensor is advantageous for the manufacture of compact color cameras with high-quality pictures, since color separation systems, such as prisms or color filter arrays, are eliminated because of the color selectivity of OPFs. To achieve a high-resolution stacked sensor, its total thickness should be reduced to less than 10 mu m. In this study, we fabricated a color image sensor with R and G-sensitive OPFs by applying amorphous In-Ga-Zn-O thin-film transistor (TFT) readout circuits. A 10 mu m-thick interlayer insulator separated the R and G-sensitive layers. The entire fabrication process for the device was implemented below 150 degrees C to avoid damaging the OPFs. Output signals were successfully read from each OPF through the TFT circuit, and multi-color images were reproduced from the fabricated sensor.