Elucidating the Detectivity Limits in Shortwave Infrared Organic Photodiodes

Wu, Zhenghui; Yao, Weichuan; London, Alexander E.; Azoulay, Jason D.; Ng, Tse Nga

doi:10.1002/adfm.201800391

Cited by 116 publications

(178 citation statements)

References 51 publications

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“…The chemicals were used as received without further purification. The device fabrication process is described in ref 9. In brief, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PE-DOT:PSS; Heraeus 4083) was diluted with isopropanol in 1:4 volume ratio to improve substrate surface wetting.…”

Section: ■ Experimental Methodsmentioning

confidence: 99%

Organic Bulk Heterojunction Infrared Photodiodes for Imaging Out to 1300 nm

Yao

Huang

et al. 2019

ACS Appl. Electron. Mater.

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This work studies organic bulk heterojunction photodiodes with a wide spectral range capable of imaging out to 1.3 μm in the shortwave infrared. Adjustment of the donor-to-acceptor (polymer:fullerene) ratio shows how blend composition affects the density of states (DOS) which connects materials composition and optoelectronic properties and provides insight into features relevant to understanding dispersive transport and recombination in the narrow bandgap devices. Capacitance spectroscopy and transient photocurrent measurements indicate the main recombination mechanisms arise from deep traps and poor extraction from accumulated space charges. The amount of space charge is reduced with a decreasing acceptor concentration; however, this reduction is offset by an increasing trap DOS. A device with 1:3 donor-to-acceptor ratio shows the lowest density of deep traps and the highest external quantum efficiency among the different blend compositions. The organic photodiodes are used to demonstrate a single-pixel imaging system that leverages compressive sensing algorithms to enable image reconstruction.

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Section: ■ Experimental Methodsmentioning

confidence: 99%

Organic Bulk Heterojunction Infrared Photodiodes for Imaging Out to 1300 nm

Yao

Huang

et al. 2019

ACS Appl. Electron. Mater.

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“…18 Leveraging this series of materials, the Ng lab demonstrated devices with spectral response up to 1700 nm. 28,29 Figure 2f displays an organic bulk heterojunction (BHJ) photodiode 30,31 that comprises an SWIR-responsive organic semiconductor used as the p-type donor intermixed with an ntype [6,6]-phenyl-C 71 -butyric acid methyl ester (PCBM[70]) acceptor. Besides fullerene derivatives, alternative oligomer acceptors designed to improve the device stability and efficiency are emerging.…”

Section: Infrared-responsive Organic Semiconductors and Device Structmentioning

confidence: 99%

Emerging Design and Characterization Guidelines for Polymer-Based Infrared Photodetectors

et al. 2018

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CONSPECTUS: Infrared photodetectors are essential to many applications, including surveillance, communications, process monitoring, and biological imaging. The short-wave infrared (SWIR) spectral region (λ = 1−3 μm) is particularly powerful for health monitoring and medical diagnostics because biological tissues show low absorbance and minimal SWIR autofluorescence, enabling greater penetration depth and improved resolution in comparison with visible light. However, current SWIR photodetection technologies are largely based on epitaxially grown inorganic semiconductors, which are costly, require complex processing, and impose cooling requirements incompatible with wearable electronics. Solution-processable semiconductors are being developed for infrared detectors to enable low-cost direct deposition and facilitate monolithic integration and resolution not achievable using current technologies. In particular, organic semiconductors offer numerous advantages, including large-area and conformal coverage, temperature insensitivity, and biocompatibility, for enabling ubiquitous SWIR optoelectronics. This Account introduces recent efforts to advance the spectral response of organic photodetectors into the SWIR. High-performance visible to near-infrared (NIR) organic photodetectors have been demonstrated by leveraging the wealth of knowledge from organic solar cell research in the past decade. On the other hand, organic semiconductors that absorb in the SWIR are just emerging, and only a few organic materials have been reported that exhibit photocurrent past 1 μm. In this Account, we survey novel SWIR molecules and polymers and discuss the main bottlenecks associated with charge recombination and trapping, which are more challenging to address in narrow-band-gap photodetectors in comparison with devices operating in the visible to NIR. As we call attention to discrepancies in the literature regarding performance metrics, we share our perspective on potential pitfalls that may lead to overestimated values, with particular attention to the detectivity (signal-to-noise ratio) and temporal characteristics, in order to ensure a fair comparison of device performance. As progress is made toward overcoming challenges associated with losses due to recombination and increasing noise at progressively narrower band gaps, the performance of organic SWIR photodetectors is steadily rising, with detectivity exceeding 10 11 Jones, comparable to that of commercial germanium photodiodes. Organic SWIR photodetectors can be incorporated into wearable physiological monitors and SWIR spectroscopic imagers that enable compositional analysis. A wide range of potential applications include food and water quality monitoring, medical and biological studies, industrial process inspection, and environmental surveillance. There are exciting opportunities for low-cost organic SWIR technologies to be as widely deployable and affordable as today's ubiquitous cell phone cameras operating in the visible, which will serve as an empowering tool for users to...

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“…We note that while the calculation of D * using Equation is a very common approach it may lead to an overestimation of the detectivity . The calculation of D * neglects the contribution of the flicker noise (1/f‐noise) and the thermal noise to the total noise current of the photodiode …”

Section: Diode Parameters Of P3ht:o‐idtbr Photodetectors Were Measurementioning

confidence: 99%

Visible and Near‐Infrared Imaging with Nonfullerene‐Based Photodetectors

Gasparini

Gregori

Salvador

et al. 2018

Adv Materials Technologies

100

115

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The solution‐processed organic photodetectors underpin an emerging technology with inherent implications in the biological sensors and imaging displays. Conventional organic photodiodes, the core element of an organic photodetector, rely mainly on fullerene‐based acceptors, which in combination with high and middle bandgap donors, limit the spectral photosensitivity to the visible range. Even in the case of low bandgap polymers the oscillator strength and thus the extinction coefficient are usually limited in the NIR due to the nature of molecular orbital hybridization. Instead, it is showed that pairing prototypical poly(3‐hexylthiophene) (P3HT) with rhodanine‐benzothiadiazole‐coupled indacenodithiophene (IDTBR), a nonfullerene electron acceptor absorbing beyond 750 nm, as the photoactive material of a simple photodiode results in a highly efficient organic photodetector with a record responsivity of 0.42 A W−1 and external quantum efficiency (EQE) of 69% in the NIR (755 nm). Nonfullerene‐based photodiodes are processed on amorphous silicon active matrix backplanes to realize large area flat panel photodetector imagers able to detect objects under visible and NIR light conditions with an exceptional combination of responsivity, dynamic response and image crosstalk.

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Elucidating the Detectivity Limits in Shortwave Infrared Organic Photodiodes

Cited by 116 publications

References 51 publications

Organic Bulk Heterojunction Infrared Photodiodes for Imaging Out to 1300 nm

Organic Bulk Heterojunction Infrared Photodiodes for Imaging Out to 1300 nm

Emerging Design and Characterization Guidelines for Polymer-Based Infrared Photodetectors

Visible and Near‐Infrared Imaging with Nonfullerene‐Based Photodetectors

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