Abstract
Here, a smart strategy for decreasing the active layer thickness of the organic photodiode down to 70 nm is demonstrated by utilizing a trap-assisted photomultiplication mechanism with the optimized chemical composition. Despite the presence of a high dark current, dramatically enhanced external quantum efficiency (EQE) via photomultiplication can allow significantly reduced active layer thickness, yielding high detectivity comparable to that of conventional Si. To achieve this, a spatially confined and electrically isolated optical sensitizer, 2,2′-((2Z,2′Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IDIC) was introduced strategically between a hole transport active layer and a cathode. A nonfullerene acceptor, IDIC, turned out to be a much more efficient sensitizer than the conventional fullerene-based acceptors, as confirmed by the effective lowering of the Schottky barrier under illumination, as well as the highest EQE exceeding 130 000%. Due to its favorable electronic structure as well as two-dimensional molecular structure, a high detectivity over 1012 Jones was successfully demonstrated while maintaining the active layer thickness as 70 nm.
Original language | English |
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Pages (from-to) | 21211-21217 |
Number of pages | 7 |
Journal | ACS Applied Materials and Interfaces |
Volume | 11 |
Issue number | 23 |
DOIs | |
Publication status | Published - 2019 Jun 12 |
Bibliographical note
Funding Information:This research was supported by Space Core Technology Development Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (Grant no. NRF-2014M1A3A3A02034707). This work was also supported by the National Research Foundation (NRF) of Korea (NRF-2016M1A2A2940911).
Publisher Copyright:
© 2019 American Chemical Society.
Keywords
- detectivity
- external quantum efficiency
- nonfullerene acceptor
- photomultiplication
- polymer photodetector
ASJC Scopus subject areas
- General Materials Science