Green-light-selective organic photodiodes for full-color imaging

• Published in: Optics express Vol. 27; no. 18; pp. 25410 - 25419
• Main Authors: Lee, Gae Hwang, Bulliard, Xavier, Yun, Sungyoung, Leem, Dong-Seok, Park, Kyung-Bae, Lee, Kwang-Hee, Heo, Chul-Joon, Jung, In-Sun, Kim, Jung-Hwa, Choi, Yeong Suk, Lim, Seon-Jeong, Jin, Yong Wan
• Format: Journal Article
• Language: English
• Published: United States 02.09.2019
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.27.025410

In this work, organic photodiodes (OPDs) based on two newly synthesized p-type dipolar small molecules are reported for application to green-light-selective OPDs. In order to reduce the blue-color absorption induced by the use of C60 as the n-type material in a bulk heterojunction (BHJ), the electron donor:electron acceptor composition ratio is tuned in the BHJ. With this light manipulation approach, the blue-wavelength external quantum efficiency (EQE) is minimized to 18% after reducing the C60 concentration in the center part of the BHJ. The two p-type molecules get a cyanine-like character with intense and sharp absorption in the green color by adjusting the strength of their donating and accepting parts and by choosing a selenophene unit as a π-linker. When combined to C60, the green-wavelength EQE reaches 70% in a complete device composed of two transparent electrodes. Finally, the optical simulation shows the good color-balance performance of hybrid full-color image sensor without an additional filter by using the developed green OPD as the top-layer in stacked device architecture.