Side-chain engineering of conjugated polymers toward highly efficient near-infrared organic photo-detectors <i>via</i> morphology and dark current management

Kang, Yeongkwon; Eun, Hyeong Ju; Kye, Hyojin; Kim, Da Hee; Heo, Junseok; Kim, Jong H.; Kim, Bong Gi

doi:10.1039/d0tc00082e

Cited by 10 publications

(7 citation statements)

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“…The chemical structure of the designed CP used in this study is shown in Figure a. It is widely accepted that high mobility in CPs can be realized by enabling the transport of charge carriers through the conjugated backbone with rigidity and planarity. , The planar geometry of CPs can be strengthened through the incorporation of electron-donating and -accepting groups in a conjugated skeletal alternatively because the electron donor–acceptor configuration can induce intramolecular CT along the conjugated framework. , Thus, donor–acceptor alternating copolymers comprising an electron-deficient 3,6-di(thiophen-2-yl)pyrrolo[3,4- c ]pyrrole-1,4(2 H ,5 H )-dione (DPP) unit and an electron-rich bithiophene unit were adopted to enhance the planarity of the backbones. In addition, fluorine (F) atoms with the highest electronegativity were introduced into the bithiophene units to further enhance the chain planarity of the resulting CPs via intramolecular S–F interactions. , The side chain not only improves the solubility but also greatly affects the morphology of the CP, such as the crystallinity, crystallite size, and inter-molecular distance, through the manipulation of the interaction between individual polymer chains. , In this regard, different side chains, which have different branched points and polarities, were introduced to the same conjugated framework to investigate their effect on the electrical properties of resulting CPs, especially on the carrier mobility and response to NO 2 .…”

Section: Resultsmentioning

confidence: 99%

“…It is widely accepted that high mobility in CPs can be realized by enabling the transport of charge carriers through the conjugated backbone with rigidity and planarity. 43,44 The planar geometry of CPs can be strengthened through the incorporation of electron-donating and -accepting groups in a conjugated skeletal alternatively because the In addition, fluorine (F) atoms with the highest electronegativity were introduced into the bithiophene units to further enhance the chain planarity of the resulting CPs via intramolecular S−F interactions. 45,46 The side chain not only improves the solubility but also greatly affects the morphology of the CP, such as the crystallinity, crystallite size, and intermolecular distance, through the manipulation of the interaction between individual polymer chains.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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NO₂-Affinitive Conjugated Polymer for Selective Sub-Parts-Per-Billion NO₂ Detection in a Field-Effect Transistor Sensor

Kang

Kwak

Kwon

et al. 2021

ACS Appl. Mater. Interfaces

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Conjugated polymers (CPs) have provided versatile semiconducting implements for the development of soft electronic devices. When three CPs with the same conjugated framework but different side chains were adopted in the field-effect transistor (FET) sensor for NO2 detection, the response to NO2 showed an opposite tendency to the charge carrier mobility of each CP. Morphological and structural characterizations revealed that the flexible glycol side chain enhances NO2 affinity as well as prevents the formation of lamellar stacking of the CP chains, thereby providing routes for the facile diffusion of NO2. Additionally, theoretical calculations for CP–NO2 complex formation at the molecular level support the relatively low energy barrier for inter-chain transition of NO2 between the glycol-based conjugated frameworks, which implies the spontaneous internal diffusion of NO2 to the semiconductor–dielectric interface in the FET-based sensor. As a result, the CP with a NO2-affinitive morphology exhibited an exceptional sensitivity of 13.8%/ppb upon NO2 (100 ppb) exposure for 50 s and provided excellent selectivity to the FET-based sensor toward other environmentally abundant harmful gases, such as SO2, CO2, and NH3. In particular, the theoretic limit of detection reached down to 0.24 ppb, which is the lowest value ever reported for organic FET-based NO2 gas sensors.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

NO₂-Affinitive Conjugated Polymer for Selective Sub-Parts-Per-Billion NO₂ Detection in a Field-Effect Transistor Sensor

Kang

Kwak

Kwon

et al. 2021

ACS Appl. Mater. Interfaces

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“…Besides, the carrier mobility is partly connected with the crystallinity of CP, and high crystalline CPs generally exhibit significantly high carrier mobility. [21][22][23] The use of partly linear side chains in the indolocarbazole unit is expected to improve the crystallization tendency of PBT. Additionally, the insertion of F atoms to the indolocarbazole unit induces intramolecular SF interactions, which planarizes the conjugated framework of PBTF, improving crystallization tendency further.…”

Section: Materials Design and Characterizationmentioning

confidence: 99%

NO₂‐Affinitive Amorphous Conjugated Polymer for Field‐Effect Transistor Sensor toward Improved NO₂ Detection Capability

Chae

Han

Ahn

et al. 2021

Adv Materials Technologies

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sensors is governed significantly by the film morphology. [7][8][9] Therefore, strategic approaches to ameliorate the sensitivity of FET-based gas sensors have been centered on the morphological optimization of the OSC layer, such as increase of the diffusion or the contact area of the gas molecules and control of the OSC-dielectric interfacial properties. [10][11][12] In addition, ultrathin film and nano/micro-structured OSCs have been utilized as FET active layers, to improve the response rate of FET sensors to target analytes. [13] In particular, as crystallinity and molecular assembly of OSCs can be easily tuned by modifying the structure of the conjugated frameworks, various polymeric OSCs have been actively studied for FET-based gas sensors. [14][15][16] Although deconvoluting the individual effects of chemical structure and morphology on the detection sensitivity of FET-based gas sensors is challenging, development of effective structures that cause significant changes in carrier density through strong interaction with the analytes is inevitable to further improve the performance of such sensors.Nitrogen dioxide (NO 2 ) is a detrimental exhaust gas abundantly released into the atmosphere from industrial sources. It is toxic and, particularly dangerous gases because of its strong oxidizing power that makes it highly reactive. Moreover, since human respiration system can be fatally damaged when exposed to low concentrations of NO 2 in closed work-spaces, health and safety agencies strongly suggest a limit of exposure of 5 ppm of NO 2 for longer than 15 min. [17] Therefore, the precise, sensitive, and efficient detection of NO 2 is of the outmost importance for human health and disease prevention. In FET-based NO 2 sensors typically utilizing a p-type OSC as an active layer, the detection and sensitivity mechanisms generally follow hole carrier generation via charge transfer interaction with electron-accepting NO 2 . [18,19] This implies that the electron-donating properties of the p-type OSC are interconnected with the NO 2 detection ability of the FET sensors. The OSC with higher electron-donating ability would be beneficial to improve the detection sensitivity to NO 2 . In this contribution, three conjugated polymers (CPs, polymeric OSCs) are designed, which share the same indolocarbazole-based conjugated framework considered as known to a good electron donor. [20] In addition, to compare the effect of the morphology on NO 2 detection, different side chains were used to modulate Three conjugated polymers (CPs) containing indolocarbazole-based similar conjugated frameworks are designed to investigate the NO 2 detection capability of field-effect transistor (FET) sensors. The partly linear aliphatic side chain strengthens the crystallization tendency of the CPs, but the crystallinity is critically degraded when introducing an ethylene oxide (EO)modified side chain to the same conjugated framework. Although the highly crystalline morphology of the CP helps to achieve high hole mobility, the NO 2 response rate...

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“…This problem becomes worse on the flexible or stretchable substrates which are essential component for wearable electronics in particular for photoplethysmography (PPG) sensors based on NIR OPDs. To suppress degree of J D in NIR OPDs, energy level tailoring for NIR-light-absorbing CPs and SMs has been carried out through organic synthesis ( Lee et al., 2019 ; Simone et al., 2020 ; Kang et al., 2020 ), while designing device architecture has been also tried such as employing charge blocking layers ( Zhou et al., 2015 ; Yang et al., 2021 ) or structural engineering in photomultiplication (PM)-type PDs ( Zhao et al., 2021a ; Liu et al., 2021a , 2021b ). However, development of new materials every time is less competitive due to its complicated procedures, and little amount of charge carriers is still injected ( Guo et al, 2020 ) even with charge blocking layers by tunneling process under high reverse bias.…”

Section: Introductionmentioning

confidence: 99%

Strain-durable dark current in near-infrared organic photodetectors for skin-conformal photoplethysmographic sensors

et al. 2022

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Side-chain engineering of conjugated polymers toward highly efficient near-infrared organic photo-detectors via morphology and dark current management

Abstract:
A side-chain engineered conjugated polymer provides outstanding NIR detectivity exceeding 2.0 × 10¹²Jones, due to enhanced photo-responsivity and suppressed dark current.

Cited by 10 publications

References 43 publications

NO₂-Affinitive Conjugated Polymer for Selective Sub-Parts-Per-Billion NO₂ Detection in a Field-Effect Transistor Sensor

NO₂-Affinitive Conjugated Polymer for Selective Sub-Parts-Per-Billion NO₂ Detection in a Field-Effect Transistor Sensor

NO₂‐Affinitive Amorphous Conjugated Polymer for Field‐Effect Transistor Sensor toward Improved NO₂ Detection Capability

Strain-durable dark current in near-infrared organic photodetectors for skin-conformal photoplethysmographic sensors

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Side-chain engineering of conjugated polymers toward highly efficient near-infrared organic photo-detectors via morphology and dark current management

Abstract: A side-chain engineered conjugated polymer provides outstanding NIR detectivity exceeding 2.0 × 1012Jones, due to enhanced photo-responsivity and suppressed dark current.

Cited by 10 publications

References 43 publications

NO2-Affinitive Conjugated Polymer for Selective Sub-Parts-Per-Billion NO2 Detection in a Field-Effect Transistor Sensor

NO2-Affinitive Conjugated Polymer for Selective Sub-Parts-Per-Billion NO2 Detection in a Field-Effect Transistor Sensor

NO2‐Affinitive Amorphous Conjugated Polymer for Field‐Effect Transistor Sensor toward Improved NO2 Detection Capability

Strain-durable dark current in near-infrared organic photodetectors for skin-conformal photoplethysmographic sensors

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Abstract:
A side-chain engineered conjugated polymer provides outstanding NIR detectivity exceeding 2.0 × 10¹²Jones, due to enhanced photo-responsivity and suppressed dark current.

NO₂-Affinitive Conjugated Polymer for Selective Sub-Parts-Per-Billion NO₂ Detection in a Field-Effect Transistor Sensor

NO₂-Affinitive Conjugated Polymer for Selective Sub-Parts-Per-Billion NO₂ Detection in a Field-Effect Transistor Sensor

NO₂‐Affinitive Amorphous Conjugated Polymer for Field‐Effect Transistor Sensor toward Improved NO₂ Detection Capability