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Sensitive photodetection below silicon bandgap using quinoid-capped organic semiconductors
Tengfei Li1, Gangjian Hu2, Liting Tao3
1Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.
Science Advances
|March 29, 2023
Summary
New organic photodetectors (OPDs) achieve high sensitivity in the near-infrared (NIR) spectrum, extending detection beyond silicon limits. These novel organic small-molecule semiconductors enable advanced applications previously unattainable with existing technologies.
Area of Science:
- Organic electronics
- Photodetector technology
- Semiconductor physics
Background:
- High-sensitivity organic photodetectors (OPDs) are crucial for emerging technologies.
- Current organic semiconductors have limited photoresponse beyond 1.1 μm, falling short of silicon detector limits.
- Extending organic semiconductor absorption into the near-infrared (NIR) is a significant challenge.
Purpose of the Study:
- To develop organic small-molecule semiconductors with extended absorption into the near-infrared (NIR) spectrum, below the silicon bandgap.
- To design and fabricate high-sensitivity photodiode-type NIR OPDs.
- To demonstrate the potential of these OPDs in applications like spectrometers and imaging.
Main Methods:
- Introduction of newly designed quinoid-terminals with high Mulliken-electronegativity (5.62 eV) to organic small-molecule semiconductors.
- Fabrication of photodiode-type near-infrared (NIR) organic photodetectors (OPDs).
- Characterization of detectivity (D*) and spectral response of the fabricated OPDs.
Main Results:
- Organic semiconductors with absorption extended to 0.77 eV were achieved.
- Fabricated photodiode-type NIR OPDs demonstrated detectivity (D*) over 10^12 Jones from 0.41 to 1.2 μm.
- A maximum detectivity of 2.9 × 10^12 Jones at 1.02 μm was recorded, the highest reported for photovoltaic-mode OPDs beyond 1.1 μm.
- Performance in the 0.9 to 1.2 μm range is comparable to commercial InGaAs detectors.
- Successful demonstration of a spectrometer prototype (0.4 to 1.25 μm) and NIR imaging under 1.2-μm illumination.
Conclusions:
- Novel quinoid-terminal engineering effectively extends organic semiconductor absorption into the NIR region.
- The developed OPDs offer ultra-high sensitivity and broad spectral coverage, rivaling commercial technologies.
- These advancements pave the way for next-generation NIR spectroscopic and imaging applications using organic electronics.
