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Photodetection spanning the short-, mid-, and long-wave infrared (SWIR-LWIR) underpins modern science and technology. Devices using state-of-the-art narrow bandgap semiconductors require complex manufacturing, high costs, and cooling requirements that remain prohibitive for many applications. We report high-performance infrared photodetection from a donor-acceptor conjugated polymer with broadband SWIR-LWIR operation. Electronic correlations within the π-conjugated backbone promote a high-spin ground state, narrow bandgap, long-wavelength absorption, and intrinsic electrical conductivity. These previously unobserved attributes enabled the fabrication of a thin-film photoconductive detector from solution, which demonstrates specific detectivities greater than 2.10 × 10 9 Jones. These room temperature detectivities closely approach those of cooled epitaxial devices. This work provides a fundamentally new platform for broadly applicable, low-cost, ambient temperature infrared optoelectronics.
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This content will become publicly available on May 5, 2026
Photothermoelectric effect in cadmium arsenide thin films for unbiased, mid-infrared photodetection
Mid-infrared photodetectors that can operate at room temperature are of great interest for a wide range of applications. Here, we demonstrate unbiased, mid-infrared (10.4 μm) photodetection in epitaxial thin films of the three-dimensional Dirac semimetal cadmium arsenide (Cd3As2), which are grown on a III–V heterostructure. We show that the photocurrent response of planar metal–Cd3As2–metal devices is consistent with the photothermoelectric effect, which is due to a temperature gradient that develops under asymmetric illumination of the device. We show that the photoresponsivity of Cd3As2 channel devices is an order of magnitude greater than devices with a III–V semiconductor channel, attesting to the excellent thermoelectric properties of Cd3As2 and promising efficient unbiased, room-temperature mid-infrared photodetection.
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- Award ID(s):
- 2118523
- PAR ID:
- 10646583
- Publisher / Repository:
- American Institute of Physics
- Date Published:
- Journal Name:
- Applied Physics Letters
- Volume:
- 126
- Issue:
- 18
- ISSN:
- 0003-6951
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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