UC San Diego
Temperature-Dependent Detectivity of Near-Infrared Organic Bulk Heterojunction Photodiodes
- Author(s): Wu, Z
- Yao, W
- London, AE
- Azoulay, JD
- Ng, TN
- et al.
Published Web Locationhttps://doi.org/10.1021/acsami.6b12162
Bulk heterojunction photodiodes are fabricated using a new donor-acceptor polymer with a near-infrared absorption edge at 1.2 μm, achieving a detectivity up to 1012 Jones at a wavelength of 1 μm and an excellent linear dynamic range of 86 dB. The photodiode detectivity is maximized by operating at zero bias to suppress dark current, while a thin 175 nm active layer is used to facilitate charge collection without reverse bias. Analysis of the temperature dependence of the dark current and spectral response demonstrates a 2.8-fold increase in detectivity as the temperature was lowered from 44 to -12 °C, a relatively small change when compared to that of inorganic-based devices. The near-infrared photodiode shows a switching speed reaching up to 120 μs without an external bias. An application using our NIR photodiode to detect arterial pulses of a fingertip is demonstrated.
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