Inorganic UV–Visible–SWIR Broadband Photodetector Based on Monodisperse PbS Nanocrystals

Lee, Jae Woong; Kim, Do Young; Baek, Sujin; Yu, Hyeonggeun; So, Franky

doi:10.1002/smll.201503244

Cited by 76 publications

(87 citation statements)

References 32 publications

(52 reference statements)

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“…The first report of an SWIR-responsive conjugated polymer appeared in 2009. 14 This material, whose structure is shown in Figure 2a, demonstrated a spectral response from 300 to 1450 nm, offering a broadly absorbing alternative to SWIR colloidal quantum dots, 25,26 which are limited to narrow spectral widths by their characteristic zero-dimensional density of states. Another conjugated polymer, shown in Figure 2b, reached a peak external quantum efficiency (EQE) of 8% at 1200 nm with an applied bias of −2 V. 15 The polymer absorption displayed a wide band tail, indicative of high structural disorder resulting in low efficiency.…”

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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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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“…Current technologies cost tens of thousands of dollars to manufacture and are not economically viable for widespread use. Alternative semiconductors are being sought for applications in the shortwave infrared (SWIR) spectral region (wavelength λ = 1–3 µm), including solution‐processed colloidal quantum dots, 2D materials, and conjugated organics, because solution processing allows low‐temperature, direct deposition on silicon readout chips that lowers costs compared to the time‐consuming, expensive, transfer‐and‐bond integration processes used in current technologies. Among the novel materials, organic molecules and polymers are the most synthetically tunable, and organic bulk heterojunction (BHJ) photodiodes have demonstrated detectivities greater than silicon in the visible and near‐infrared spectral regions.…”

Section: Introductionmentioning

confidence: 99%

Elucidating the Detectivity Limits in Shortwave Infrared Organic Photodiodes

Yao

London

et al. 2018

Adv Funct Materials

114

173

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While only few organic photodiodes have photoresponse past 1 µm, novel shortwave infrared (SWIR) polymers are emerging, and a better understanding of the limiting factors in narrow bandgap devices is critically needed to predict and advance performance. Based on state-of-the-art SWIR bulk heterojunction photodiodes, this work demonstrates a model that accounts for the increasing electric-field dependence of photocurrent in narrow bandgap materials. This physical model offers an expedient method to pinpoint the origins of efficiency losses, by decoupling the exciton dissociation efficiency and charge collection efficiency in photocurrent-voltage measurements. These results from transient photoconductivity measurements indicate that the main loss is due to poor exciton dissociation, particularly significant in photodiodes with low-energy charge-transfer states. Direct measurements of the noise components are analyzed to caution against using assumptions that could lead to an overestimation of detectivity. The devices show a peak detectivity of 5 × 10 10 Jones with a spectral range up to 1.55 µm. The photodiodes are demonstrated to quantify the ethanol-water content in a mixture within 1% accuracy, conveying the potential of organics to enable economical, scalable detectors for SWIR spectroscopy.

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“…Moreover, QDs are in favor of the tunable absorption spectrum by controlling the size of the QDs during the synthesis process [19]. Specifically, lead sulfide (PbS) QDs have been widely employed in photodetectors because of their inherent narrow bandgap (~1.3 eV) and tunable absorption spectra from the nearinfrared (NIR) to visible (Vis) [21,22]. So far, PbS QDs as essential photoactive layers have been utilized to construct different kinds of optoelectronic devices, such as p-n junction photodiodes, PIN photodetectors, and solar cells [23][24][25].…”

Section: Introductionmentioning

confidence: 99%

High-performance flexible and broadband photodetectors based on PbS quantum dots/ZnO nanoparticles heterostructure

et al. 2018

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Flexible and broadband photodetectors have drawn extensive attention due to their potential application in foldable displays, optical communications, environmental monitoring, etc. In this work, a flexible photodetector based on the crystalline PbS quantum dots (QDs)/ZnO nanoparticles (NPs) heterostructure was proposed. The photodetector exhibits a broadband response from ultraviolet-visible (UV-Vis) to near infrared detector (NIR) range with a remarkable current on/off ratio of 7.08×10 3 under 375 nm light illumination. Compared with pure ZnO NPs, the heterostructure photodetector shows the three orders of magnitude higher responsivity in Vis and NIR range, and maintains its performance in the UV range simultaneously. The photodetector demonstrates a high responsivity and detectivity of 4.54 A W −1 and 3.98×10 12 Jones. In addition, the flexible photodetectors exhibit excellent durability and stability even after hundreds of times bending. This work paves a promising way for constructing next-generation high-performance flexible and broadband optoelectronic devices.

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Inorganic UV–Visible–SWIR Broadband Photodetector Based on Monodisperse PbS Nanocrystals

Cited by 76 publications

References 32 publications

Emerging Design and Characterization Guidelines for Polymer-Based Infrared Photodetectors

Emerging Design and Characterization Guidelines for Polymer-Based Infrared Photodetectors

Elucidating the Detectivity Limits in Shortwave Infrared Organic Photodiodes

High-performance flexible and broadband photodetectors based on PbS quantum dots/ZnO nanoparticles heterostructure

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