Efficient Organic Upconversion Devices for Low Energy Consumption and High‐Quality Noninvasive Imaging

Du, Xiaoyang; Han, Jiayue; He, Zhihua; Han, Chao; Wang, Xiaomu; Wang, Jun; Jiang, Yadong; Tao, Silu

doi:10.1002/adma.202102812

Cited by 29 publications

(45 citation statements)

References 34 publications

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“…A few reported single‐parameter 3dB cut‐off frequencies such as rise and fall times show that the response speed of OUCs so far is limited to around 10 kHz. [ 10,11,14,15 ] This is much lower than the response speed of organic NIR photodetectors, for which typical cut‐off frequencies are well above 100 kHz. [ 19,35,50,51 ] We think that the main reason for this discrepancy is the low electric field in the emitter layer present in OUCs.…”

Section: Resultsmentioning

confidence: 99%

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On the Response Speed of Narrowband Organic Optical Upconversion Devices

Vael

Diethelm

et al. 2022

Advanced Optical Materials

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and are still cost prohibitive for most consumer and low-end applications. In addition, due to the broadband absorption of inorganic semiconductors, spectrally selective detection is not possible without attached optical filters.As an alternative approach, optical upconversion devices have been developed that directly convert NIR light into visible light. These devices are also denoted as upconversion photodetector, [9] upconversion display/imager, [10,11] or upconversion light-emitting diode. [12] The basic idea of any upconverter is the serial connection of a NIR photodetector with a visible lightemitting component. When NIR light is absorbed in the photodetector, a current is generated and directly converted into a visible image by the emitter element. Important advantages of this design concept are that no intermediate electronics for data processing and no external display for data visualization are required. We note that the functionality of an upconverter is different from the several known photon upconversion processes. Photon upconversion is a process that converts sequentially absorbed photons of low energy into a photon of higher energy.All-organic upconversion devices (OUCs) are composed of an organic NIR photodetector and an organic light-emitting diode (OLED). OUCs can be fabricated entirely from solution over large area using coating and printing processes. This potentially enables new and alternative NIR imaging applications Organic upconversion devices (OUCs) consist of an organic infrared photodetector and an organic visible light-emitting diode (OLED), connected in series. OUCs convert photons from the infrared to the visible and are of use in applications such as process control or imaging. Many applications require a fast OUC response speed, namely the ability to accurately detect in the visible a rapidly changing infrared signal. Here, high image-contrast, narrowband OUCs are reported that convert near-infrared (NIR) light at 980 and 976 nm with a full-width at half maximum of 130 nm into visible light. Transient photocurrent measurements show that the response speed decreases when lowering the NIR light intensity. This is contrary to conventional organic photodetectors that show the opposite speed-versus-light trend. It is further found that the response speed increases (when using a phosphorescent OLED) or decreases (for a fluorescent OLED) when increasing the driving voltage. To understand these surprising results, an analysis by numerical simulation is conducted. Results show that the response speed behavior is primarily determined by the electron mobility in the OLED. It is proposed that the low electron drift velocity in the emitter layer sets a fundamental limit to the response speed of OUCs.

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Section: Resultsmentioning

confidence: 99%

“…[16] Since then, research efforts were directed to extend the detection into the shortwave infrared range, i.e., beyond 1000 nm, [ 11,12,17,18 ] or to improve important device figures of merit, such as lowering the operating voltage or improving the NIR light sensitivity. [ 10,14,15 ]…”

Section: Introductionmentioning

confidence: 99%

On the Response Speed of Narrowband Organic Optical Upconversion Devices

Vael

Diethelm

et al. 2022

Advanced Optical Materials

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“…The specific detectivity (D*) reflects the signal-to-noise ratio and detection capability of advanced photodetectors to weak light. 33,34 It is widely accepted that D* can be expressed as…”

Section: Resultsmentioning

confidence: 99%

Self-assembled graphene/BUBD-1 hybrids for ultrasensitive organic phototransistors

Qin

et al. 2022

J. Mater. Chem. C

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“…The NIR‐II region contains 1000–1700 nm with in‐depth of penetration through the biological sample, which is eligible for noninvasive imaging technology. [ 222,223 ] Fluorescence organic molecule and upconversion nanocrystals are widely used in noninvasive biological imaging, suggesting great potential for preclinical research and clinical application. [ 224,225 ] Moreover, the noncontact heart rate monitor without signal amplification is implemented by phototransistor graphene/ZnO/IEICO‐4F:PTB7‐Th at NIR regime as depicted in Figure a,b.…”

Section: Applications and Prospectsmentioning

confidence: 99%

Recent Progress in 2D Inorganic/Organic Charge Transfer Heterojunction Photodetectors

Han

Wang

Han

et al. 2022

Adv Funct Materials

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2D materials possess superior optoelectronic properties, such as ultrahigh mobility and broadband photoresponse, making them one of the most vital platforms for diversified photodetectors. However, atomic thickness 2D materials usually suffer from intrinsic low absorption. To promote the photo detector performance, a feasible method is to integrate the 2D materials with lowcost, flexible, and tunable organics that form a charge transfer (CT) heterojunction. As results, indepth multifunctional CT 2Dinorganic/organic detector exhibits extended functions such as lowpower consumption, in memory detection, and opticalbio synapse to meet the demand of contem porary photonic cell. Particularly, the progresses in waferscale monocrystal of both 2D and organic materials render vast potential applications with operation frequencies ranging from ultraviolet to terahertz. Here, the recent advances of 2Dinorganic/organic CT photodetectors are comprehensively reviewed by several classifications. Future developments and applications in optical biology, synapsis, and machine vision are also highlighted.

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Efficient Organic Upconversion Devices for Low Energy Consumption and High‐Quality Noninvasive Imaging

Cited by 29 publications

References 34 publications

On the Response Speed of Narrowband Organic Optical Upconversion Devices

On the Response Speed of Narrowband Organic Optical Upconversion Devices

Self-assembled graphene/BUBD-1 hybrids for ultrasensitive organic phototransistors

Recent Progress in 2D Inorganic/Organic Charge Transfer Heterojunction Photodetectors

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