Vitality surveillance at distance using thin-film tandem-like narrowband near-infrared photodiodes with light-enhanced responsivity

Abstract

Remote measurement of vital sign parameters like heartbeat and respiration rate represents a compelling challenge in monitoring an individual’s health in a noninvasive way. This could be achieved by large field-of-view, easy-to-integrate unobtrusive sensors, such as large-area thin-film photodiodes. At long distances, however, discriminating weak light signals from background disturbance demands superior near-infrared (NIR) sensitivity and optical noise tolerance. Here, we report an inherently narrowband solution–processed, thin-film photodiode with ultrahigh and controllable NIR responsivity based on a tandem-like perovskite-organic architecture. The device has low dark currents (<10 −6 mA cm −2 ), linear dynamic range >150 dB, and operational stability over time (>8 hours). With a narrowband quantum efficiency that can exceed 200% at 850 nm and intrinsic filtering of other wavelengths to limit optical noise, the device exhibits higher tolerance to background light than optically filtered silicon-based sensors. We demonstrate its potential in remote monitoring by measuring the heart rate and respiration rate from distances up to 130 cm in reflection.

Organic photodetectors: materials, device, and challenges

“…5(e)). 72 The tandem-like device had a responsivity of 1.5 A W À1 at 850 nm, low dark currents (o10 À6 mA cm À2 ), and linear dynamic range of 4150 dB (Fig. 5(f)).…”

“…6(b)). 65,72,[74][75][76][77][78][79][80][81] It is worth mentioning that the complex device structure will inevitably lead to a corresponding increase in processing costs of organic tandem photodetectors as shown in Fig. 7, which may place great restrictions on their commercial applications.…”

“…(c) and (d) Schematic device architecture and D* spectrum of the dual-mode response organic tandem photodetector 71. (e)-(g) Schematic device architecture and responsivity spectrum of the organic-inorganic tandem photodetector 72.…”

Enhanced sub-1 eV detection in organic photodetectors through tuning polymer energetics and microstructure

“…Visible and infrared (IR) photodetectors based on silicon and indium gallium arsenide (InGaAs) dominate the current market thanks to their outstanding optoelectronic properties, with specific detectivity exceeding 10 12 Jones. Notwithstanding, their lack of flexibility and costly manufacturing processes have left room for other emerging technologies such as organic photodetectors (OPDs) (3,4). Organic optoelectronics can address the fastgrowing demand for portable, lightweight, cost-effective sensors that are flexible and easy to integrate and scale (5)(6)(7)(8).…”

High‐Performance Filterless Blue Narrowband Organic Photodetectors

“…[1][2][3][4] Their ubiquitous presence in biomedicine, agriculture, surveillance, and optical communication necessitates further highly photosensitive, fast responding, and high detectivity devices to be devised. [5][6][7][8] Fine-tuning the parameters for customized commercial criteria is pivotal for the success of any sensing application. Organic semiconductors, albeit their lower charge carrier mobility and high exciton binding energy, outperform their inorganic DOI: 10.1002/adfm.202308719 counterparts in terms of nontoxicity, flexibility, low cost, and molecular design versatility.…”