title: Temperature-Dependent Detectivity of Near-Infrared Organic Bulk Heterojunction Photodiodes.
abstract: 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 1012Jones 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.
authors.affiliation: Department of Electrical and Computer Engineering, University of California San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Zhenghui
authors.identifier: http://orcid.org/0000-0002-4187-9280
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Department of Electrical and Computer Engineering, University of California San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Weichuan
authors.initials: W
authors.lastname: Yao
authors.affiliation: School of Polymers and High Performance Materials, University of Southern Mississippi , 118 College Drive #5050, Hattiesburg, Mississippi 39406, United States.
authors.forename: Alexander E
authors.initials: AE
authors.lastname: London
authors.affiliation: School of Polymers and High Performance Materials, University of Southern Mississippi , 118 College Drive #5050, Hattiesburg, Mississippi 39406, United States.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Azoulay
authors.affiliation: Department of Electrical and Computer Engineering, University of California San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Tse Nga
authors.initials: TN
authors.lastname: Ng
keywords: activation energy; detectivity; near-infrared photodetector; organic bulk heterojunction; physiological sensing; temperature dependence