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 10 12 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.

Emerging Design and Characterization Guidelines for Polymer-Based Infrared Photodetectors

“…Figure 1c highlights that the detectivity, or signal-to-noise ratio, of an organic photodiode is less adversely affected by changes in temperature compared with a germanium photodiode. 24…”

Donor–acceptor polymers with tunable infrared photoresponse

“…The fabrication and measurement procedures were carried out as previously reported. 21 Based on the energy level diagram in Fig. 4a, charge separated carriers can be efficiently generated by PET and subsequently transported via the BHJ nanomorphology to opposite electrodes.…”

A Platform to Study the Effects of Electrical Stimulation on Immune Cell Activation During Wound Healing

“…Biosys. 2019, 3,1900106 Both screen-printed and inkjet-printed electrodes were covered with a conducting polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) to provide a stable, biocompatible interface, [20,[36][37][38][39] to further lower the impedance at the electrode-skin interface, and to provide a greater charge injection capacity for ES than metal surfaces. [22,23] As shown in Figure S2, Supporting Information, the electrodes without PEDOT:PSS coated on the ends exhibited a reduction in current supplied over time, reducing from 300 µA to less than 10 µA current after 40 min, while the PEDOT:PSS-coated electrodes maintained the current magnitude for the full 1 h stimulation time.…”

“…[21] The traces were insulated by attaching a Teflon tape on top, with vias in the tape having been cut by a laser-cutter. [3] and shown in Figure 2D Both screen-printed and inkjet-printed electrodes were covered with a conducting polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) to provide a stable, biocompatible interface, [20,[36][37][38][39] to further lower the impedance at the electrode-skin interface, and to provide a greater charge injection capacity for ES than metal surfaces. We demonstrated the capability of these arrays to map areas of varying impedance, as found in wound areas which would have lower impedance in regions with damaged skin compared to undamaged skin.…”