Effect of photogenerated carrier distribution on performance enhancement of photomultiplication organic photodetectors

Wang, Wenyan; Shi, Linlin; Zhang, Ye; Li, Guohui; Zhu, Furong; Wang, Kaiying; Cui, Yanxia

doi:10.1016/j.orgel.2019.01.055

Cited by 18 publications

(8 citation statements)

References 37 publications

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“…Since the applied bias also lowers the cathode Schottky junction, the injected carriers under illumination can ow smoothly from the blend towards the cathode. 35,36 It is seen from Fig. 1b that the photocurrent response of Al 2 O 3 -PM-OPD under a forward bias of 19 V was much higher than its response under a reverse bias of -19 V. Moreover, compared with the control device that can only work under a reverse bias, Al 2 O 3 -PM-OPD shows much superior responses under a forward bias.…”

Section: Resultsmentioning

confidence: 94%

Atomic-level Chemical Reaction Promoting External Quantum Efficiency of Organic Photodetector Exceeding 10^8% for Weak-Light Detection

Shi

Zhu

et al. 2022

Preprint

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Low-cost, solution-processed photomultiplication organic photodetectors (PM-OPDs) with external quantum efficiency (EQE) above unity have attracted enormous attention. However, their weak-light detection is unpleasant because the anode Ohmic contact causes exacerbation in dark current. Here, we introduce atomic-level chemical reaction in PM-OPDs which can simultaneously suppress dark current and increase EQE via depositing a 0.8 nm thick Al2O3 by atomic layer deposition. Suppression in dark current mainly originates from the built-in anode Schottky junction as a result of work function decrease of hole-transporting layer of which the chemical groups can react chemically with the bottom surface of Al2O3 layer at the atomic-level. Such strategy of suppressing dark current is not adverse to charge injection under illumination; instead, responsivity enhancement is realized because charge injection can shift from cathode to anode, of which the neighborhood possesses increased photogenerated carriers. Consequently, weak-light detection limit of the Al2O3 treated PM-OPD reaches a remarkable level of 2.5 nW/cm2, while that of the control is 25 times inferior. Meanwhile, the PM-OPD yields a record high EQE and responsivity of 4.31×108% and 1.85×106 A/W, respectively, outperforming all other polymer-based PM-OPDs.

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Section: Resultsmentioning

confidence: 94%

Atomic-level Chemical Reaction Promoting External Quantum Efficiency of Organic Photodetector Exceeding 10^8% for Weak-Light Detection

Shi

Zhu

et al. 2022

Preprint

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“…The use of the Al 2 O 3 interfacial layer also helps to increase the work function of the PEDOT:PSS HTL, so that the J D can be suppressed effectively in the PM‐OPDs operated under a forward bias which thus enables the photomultiplication behavior be realized through charge injection from the anode. [ 29–32 ] Therefore, with the help of interfacial modification, the CIN‐induced narrowband response at 650 nm with an FWHM of 40 nm is demonstrated for the PM‐OPDs operated under a forward bias of 60 V, leading to a peak R of 1334 A W −1 and a peak D * 9.73 × 10 13 Jones, which are 1.82 and 18.28 times higher than that obtained for the control device. The responsivity and detectivity of the proposed device outperform the performances of all other CIN‐induced narrowband PM‐OPDs.…”

Section: Introductionmentioning

confidence: 91%

High Responsivity of Narrowband Photomultiplication Organic Photodetector via Interfacial Modification

Jia

Zhang

Shi

et al. 2023

Advanced Optical Materials

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Narrowband‐response organic photodetectors with high responsivity are widely demanded in areas of substance detection, industry automation, smart wearable devices, etc. Photomultiplication‐type organic photodetectors (PM‐OPDs) with high responsivity usually have a broadband photoresponse due to the broadband absorption nature of the photoactive materials. In this work, effort is made to develop a high‐performance filterless narrowband PM‐OPD using the charge injection narrowing (CIN) effect. A 0.8 nm thick Al2O3 interlayer is used to mitigate the dark current density (JD) in the narrowband PM‐OPD, prepared using a 2.8 µm thick blend layer of P3HT:[6,6]‐phenyl‐C70‐butyric acid methyl ester (PC70BM), achieving a peak responsivity of 1334 A W−1 at 650 nm, with a full‐width at half‐maximum of 40 nm. The narrowband PM‐OPD also possesses an impressive high specific detectivity of 9.73 × 1013 Jones. It is shown that the use of a 0.8 nm thick Al2O3 interlayer significantly suppresses the JD, creating a high energy barrier at the anode/photoactive interface and achieving a narrowband photoresponse behavior due to the CIN effect. The results of this work provide an exciting option for a variety of applications for OPDs with low cost, flexibility, and high sensitivity.

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“…Photogenerated electrons are trapped by a localized acceptor near the Schottky interface, inducing band bending under illumination. Photomultiplication is achieved by the photoinduced injection of circulating holes from the external circuit to the photoactive layer under reverse bias [22–23] . In addition, barrier modification assisted by the tunneling effect or contact is also considered a key mechanism for increasing the gain [24–28] .…”

Section: Figurementioning

confidence: 99%

“…Photomultiplication is achieved by the photoinduced injection of circulating holes from the external circuit to the photoactive layer under reverse bias. [22][23] In addition, barrier modification assisted by the tunneling effect or contact is also considered a key mechanism for increasing the gain. [24][25][26][27][28] While the application of these strategies has greatly boosted the EQE of organic photodetectors (Table S1), [29][30][31][32][33][34][35][36][37][38][39] the gains are generally obtained by requiring a high bias accompanied with a high dark current, and the multiplied photocurrent often displays a slow transient response.…”

mentioning

confidence: 99%

Enhanced Gain in Organic Photodetectors Using the Polymer with Singlet Open‐Shell Ground State

Dang,

Hu,

Yuan

et al. 2023

Angew Chem Int Ed

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Photodetectors are critical components in intelligent optoelectronic systems, and photomultiplication‐capable devices are essential for detecting weak optical signals. Despite significant advances, developing a photomultiplication‐type organic photodetectors with high gain and low noise current simultaneously remains challenging. In this work, a new conjugated polymer PDN with singlet open‐shell ground state is introduced in active layers for electron capture, and the corresponding PDN‐based photodetectors exhibited an enhanced photoelectric gain and decreased dark current density at a low forward bias. At 1.5 V, the PDN‐based ternary photodetector have the external quantum efficiency (EQE) up to 2552.3 % and the specific detectivity of 1.4 × 10e14 Jones at 710 nm calculated by the measured noise current, with the gain 22 times higher than that of the control group. This study provides an approach for exploiting polymers with singlet open‐shell ground state to enhance the gain of organic photodetectors.

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Effect of photogenerated carrier distribution on performance enhancement of photomultiplication organic photodetectors

Cited by 18 publications

References 37 publications

Atomic-level Chemical Reaction Promoting External Quantum Efficiency of Organic Photodetector Exceeding 10^8% for Weak-Light Detection

Atomic-level Chemical Reaction Promoting External Quantum Efficiency of Organic Photodetector Exceeding 10^8% for Weak-Light Detection

High Responsivity of Narrowband Photomultiplication Organic Photodetector via Interfacial Modification

Enhanced Gain in Organic Photodetectors Using the Polymer with Singlet Open‐Shell Ground State

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