| 학회 | 한국재료학회 |
| 학술대회 | 2018년 가을 (11/07 ~ 11/09, 여수 디오션리조트) |
| 권호 | 24권 2호 |
| 발표분야 | 5. 유기 및 2D 반도체 박막 형성 및 성능 제어(control of thin-film crystallization and characteristics of organic and |
| 제목 | Prospects of organic image sensors |
| 초록 | Over the last decade, the industry has put into continuous efforts to explore image sensor technologies for increasing their number of pixels. The resulting new integrating-technologies such as ‘back side illumination’ have dramatically improved sensor resolution, however, in order to further boost image quality, it is necessary to expand the dynamic range, enhance sensitivity and prevent cross-talk or color mixing between pixels. In this regard, the conventional Si CMOS image sensor has fundamental limitations of 1) low absorption coefficient, 2) panchromatic absorption and 3) long light travel distance. Interestingly, organic CMOS image sensor has a great potential to overcome all those drawbacks of Si CMOS so that the pixel size of image sensor can be further decreased. Nonetheless, there has been no report of realizing all these issues based on organic semiconductors. Especially, to achieve 2) and 3), organic photodiode should possess a wavelength selectivity so that multicolor imaging is possible without the use of color-filter. Such a wavelength selectivity is very difficult to be realized by bulk heterojuntion (BHJ) structure, mostly used for organic photodiode. As is well known, in the case of organic semiconductor, due to relatively shorter exciton diffusion length, BHJ structure is often employed in photodiode device to maximize photo-generated current. However, such BHJ photodiodes inevitably require the use of two apparently different organic semiconductors (p-type and n-type), and therefore, it is extremely difficult to confine the absorption to the specific wavelength (R/G/B). This implies that a new junction system should be developed for constructing wavelength-selective photodiode. Here we demonstrate a thin film, narrow-band, color-selective and high performance polymeric photodiode based on various junction strategy. Our new junction structure allows remarkably low dark current by suppressing dark current injection under the reverse saturation regime, thus enhancing the signal to noise ratio of the photodiode. In addition, due to the well-defined planar heterojunction geometry, we can finely define the transit time so that the temporal response of the photodiode can be optimized. As a result, we could realize high performance R/G/B/NIR-selective photodiodes. |
| 저자 | 정대성 |
| 소속 | 대구경북과학기술원 |
| 키워드 | Organic photodiode; color filter free; thin film; image sensor; polymer semiconductor |
