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High detectivity organic photodetectors in the visible light wavelength with ternary bulk heterojunction
摘要： In this work, we report an ternary bulk heterojunction (t-BHJ) organic photodetectors (OPDs) based on P3HT, PTB7 and PC61BM. The effects of PTB7 added to P3HT:PC61BM on the optical and electrical properties of OPDs were investigated. It is found that when the mass ratio of P3HT:PTB7:PC61BM is 8:2:10, the response spectrum of the active layer is extended to 780 nm, The responsivity (R) and external quantum efficiency (EQE) of the OPDs are reached 178, 291, 241 mA/W and 35%, 68%, 65%, under 630, 530, and 460 nm illumination and ?1 V bias, respectively, and the detectivity (D*) reached 1012 Jones. The results show that the addition of PTB7 with appropriate mass ratio can increases the exciton generation and dissociation probability in P3HT:PC61BM, which increases the photocurrent of the device. In addition, the addition of PTB7 promotes the crystallization of the film, reduces the density of trap defects in the film, and reduces the dark current of the device.
关键词： Microscopic morphology,Organic photodetectors,Ternary bulk heterojunction,Exciton dissociation
更新于2025-09-12 10:27:22
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Long Wavelength Lead Sulfide Quantum Dots Sensing up to 2600 nm for Short Wavelength Infrared Photodetectors
摘要： Lead sulfide nanoparticles (PbS NPs) are used in the short wavelength infrared (SWIR) photodetectors because of their excellent photosensitivity, bandgap tunability, and solution processability. It has been a challenge to synthesize high quality PbS NPs with an absorption peak beyond 2000 nm. In this work, using PbS seed crystals with an absorption peak at 1960 nm, we report a successful synthesis of very large mono-dispersed PbS NPs having a diameter up to 16 nm by multiple injections. The resulting NPs have an absorption peak over 2500 nm with a small full-width-at-half-maximum (FWHM) of 24 meV. To demonstrate the applications of such large QDs, broadband heterojunction photodetectors are fabricated with the large PbS QDs of an absorption peak at 2100 nm. The resulting devices have an EQE of 25% (over 50% IQE) at 2100 nm corresponding to a responsivity of 0.385 A/W, and an EQE ~60% in the visible range.
关键词： sensing up to 2600 nm,infrared photodetectors,Lead sulfide quantum dots,multiple injections,mono-dispersity
更新于2025-09-12 10:27:22
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Waveguide-integrated, plasmonic enhanced graphene photodetectors
摘要： We present a micrometer scale, on-chip integrated, plasmonic enhanced graphene photodetector (GPD) for telecom wavelengths operating at zero dark current. The GPD is designed to directly generate a photovoltage by the photo-thermoelectric effect. It is made of chemical vapor deposited single layer graphene, and has an external responsivity～12.2V/W with a 3dB bandwidth～42GHz. We utilize Au split-gates to electrostatically create a p-n-junction and simultaneously guide a surface plasmon polariton gap-mode. This increases light-graphene interaction and optical absorption and results in an increased electronic temperature and steeper temperature gradient across the GPD channel. This paves the way to compact, on-chip integrated, power-ef?cient graphene based photodetectors for receivers in tele and datacom modules.
关键词： plasmonics,graphene,integrated photonics,photo-thermoelectric effect,photodetectors
更新于2025-09-12 10:27:22
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Ultrasensitive Organic‐Modulated CsPbBr <sub/>3</sub> Quantum Dot Photodetectors via Fast Interfacial Charge Transfer
摘要： The integration of organic materials with colloidal quantum dots (QDs) has the merits the advantages of the molecular diversity and photoelectric tunability for ultrasensitive photodetector applications. Herein, a uniform CsPbBr3 QD layer is sandwiched between the same poly-(N, N′-bis-4-butylphenyl-N, N′-bisphenyl) benzidine (Poly-TPD) and phenyl-C61-butyric acid methyl ester (PCBM) (1:1) organic blend films. The CsPbBr3 QD layer efficiently absorbs the excitation light, where the generated exciton can sufficiently diffuse to the interface of QD and organic blend layers for efficient charge separation and effective gate modulation. Owing to the desirable heterojunction at the interface, the dark current is substantially suppressed, while the photocurrent is increased in comparison with those of pristine QDs photodetectors. The ultrafast charge transfer time (≈300 ps) from QDs to organic blend layer measured by the time-resolved transient absorption spectroscopy is potentially benefit the enhanced electron–hole pair dissociation. The solution-processed, organic (Poly-TPD:PCBM blend)-modulated CsPbBr3 QDs photodetector are exhibited ultrasensitive photoresponse abilities in terms of in terms of noise equivalent power (NEP = 1 × 10?16 W Hz?0.5), ILight/IDark ratio (2 × 103), and the a specific detectivity (D* = 4.6 × 1013 Jones). The results will be a starting point for ultrasensitive next-generation light detection technologies.
关键词： detectivity,organic materials,solution-processed,photodetectors,perovskite quantum dots
更新于2025-09-12 10:27:22
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Photodetector of Shortwave Infrared Range of Format 640 × 512 Elements with Increased Dynamic Range
摘要： The paper substantiates the necessity of expanding the dynamic range in a shortwave infrared (SWIR) photodetector (PD). The traditionally used methods have low efficiency, especially in large-format matrices with a step of not more than 15 μm. The greatest efficiency of expanding the dynamic range (up to 100 dB) is provided by accumulative cells with individually variable transfer characteristic depending on the brightness of the fragments of the observed scene. The paper proposes a simple, in topological implementation, and effective way of expanding the dynamic range based on the auto-tuning of accumulation time individually in each cell of the integrated reading circuit. At the same time, the high steepness and linearity of the transformation in the storage cells with moderate illumination (up to 50–70% of the maximum signal) remains, but the sensitivity in the cells close to saturation decreases. As a result, a linear-log transfer characteristic is formed, providing an extended dynamic range. The paper provides examples of images with an extended dynamic range obtained using the first domestic SWIR camera of format 640 × 512 elements.
关键词： photodiodes,InGaAs,LSI readout,shortwave infrared range,expansion of the dynamic range,photodetectors
更新于2025-09-12 10:27:22
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Impact of electron transport layer material on the performance of CH3NH3PbBr3 perovskite-based photodetectors
摘要： In the present article, the electron transport materials titanium oxide (TiO2), bathocuproine (BCP) and phenyl-C61-butyric acid methyl ester (PCBM) were synthesized and investigated for the application in methylammonium lead bromide (CH3NH3PbBr3) perovskite photodetectors. Results show that device based on TiO2 electron transport layer (ETL) shows higher photocurrent, responsivity and detectivity as compared to the devices based on BCP and PCBM ETL. However, ideality factor, charge carrier mobility, trap width and trap density were found to be comparable for the devices composed of BCP ETL and TiO2 ETL. The TiO2 ETL might help in the passivation of interface traps, form good quality intimate interfaces and offers more appropriate energy levels for effective blocking of holes and efficient extraction of electrons, resulting in the improved device performance. Through impedance spectroscopy analysis, the superior performance of the device with TiO2 ETL can be attributed to the better contact selectivity and high recombination resistance.
关键词： PCBM,electron transport layer,BCP,TiO2,perovskite photodetectors,CH3NH3PbBr3
更新于2025-09-12 10:27:22
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ZnO nanorods array as light absorption antenna for high-gain UV photodetectors
摘要： Hydrothermal method provides the advantages of simple, low-temperature growth conditions, low cost and large surface areas for the samples. Also, exciton dissociation can be enhanced by surface plasmon resonance (SPR) due to the plasmonic absorption enhancement of incident light. In this paper, high-gain ultraviolet (UV) photodetectors based on vertically aligned ZnO nanorods (ZnO-NRs) array as light absorption antenna were presented, in which ZnO-NRs array was prepared by hydrothermal method. Our experimental data showed that the device performance of the UV photodetector Au/ZnO(ZnO-NRs:Au-NPs)/Au can be further enhanced after the gaps of ZnO-NRs array were filled with Au nanoparticles (Au-NPs). The photo-to-dark current ratio and the specific detectivity of the UV photodetector Au/ZnO(ZnO-NRs:Au-NPs)/Au reached to 1×105 and 1.84×1013 Jones at 2 V under 100 μW/cm2 365 nm illumination, respectively. The physical mechanism for the enhanced performance of the UV photodetectors is discussed.
关键词： Surface plasmon resonance (SPR),ZnO nanorods (ZnO-NRs) array,Ultraviolet (UV) photodetectors,Hydrothermal method,Schottky contact
更新于2025-09-12 10:27:22
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Ultrasensitive Fiber-based ZnO Nanowire Network Ultraviolet Photodetector Enabled by the Synergism of Interface and Surface Gating Effects
摘要： Flexible UV photodetector with high on/off ratio is extremely important for environmental sensing, optical communication and flexible optoelectronic devices. In this work, a flexible fiber-based UV photodetector with ultrahigh on/off ratio is developed by utilizing the synergism between interface and surface gating effects on ZnO nanowire network structure. The synergism of two gating effects is realized by the interplay of surface band bending and the Fermi level through nanowire-network structure, which is proved through the control experiments between ZnO micro/nanowire photodetector and micro/nanowire-junction photodetector, and the corresponding KPFM measurements. The on/off ratio of fiber-based ZnO nanowire-network UV photodetector reaches 1.98×108 when illuminated by 1.0 mW cm?2 UV light, which is 20 times larger than the largest reported result under the same UV illumination. This new UV sensor also has the high resolution to UV light intensity change in nW cm?2 range. Furthermore, when the fiber-based photodetector is curved, it still shows the excellent performance as above. This work gives a new effective route for the development of high-performance UV photodetector or other optoelectronic detection devices.
关键词： ZnO,synergetic gating effects,flexible electronics,UV photodetectors,on/off ratio
更新于2025-09-12 10:27:22
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[IEEE 2019 26th International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD) - Kyoto, Japan (2019.7.2-2019.7.5)] 2019 26th International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD) - Effect of Device Structure on the Narrow-band Light Detection of Bulk Heterostructure Organic Photodetectors based on Poly(3-hexylthiophene) and Fullerene Derivative
摘要： The characteristics of organic photodetectors based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) blends with various film thicknesses of active layer are investigated. The red-shift in peak wavelength of incident-photon-to-current conversion efficiency (IPCE) spectra in the devices with various film thicknesses is observed with increasing film thickness. For thick devices upon irradiation by light with a photon energy of around energy gap of an active layer, excitons are formed almost uniformly because of the small absorption coefficient of red light. A conventional device with 2 μm-thick film exhibits narrow-band light detection with red-light sensitivity and the relatively narrow spectral response of the full-width at half-maximum (FWMH) of around 50 nm. On the other hand, an inverted device with 2 μm-thick film exhibits broadband light detection. For bulk heterostructure devices, one of important factors to realize the narrowband light detection is the control of charge carrier collection efficiency at electrodes which is attributed to the device structure, including the intrachain transport in polymer.
关键词： PCBM,bulk heterostructure,organic photodetectors,narrow-band light detection,P3HT
更新于2025-09-12 10:27:22
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Phase-transition modulated, high-performance dual-mode photodetectors based on WSe <sub/>2</sub> /VO <sub/>2</sub> heterojunctions
摘要： Photodetectors based on two-dimensional (2D) transition metal dichalcogenides (TMDs) can only be operated in a single photovoltaic or photoconductive mode, showing either high detectivity or high responsivity, but not both. An effort to develop a photodetector that can dynamically switch its working mode is indispensable for practical applications. In this article, we demonstrate a high performance, phase-transition modulated, dual-mode photodetector based on WSe2/VO2 heterojunction. Enabled by the insulator-to-metal transition of VO2, the WSe2/VO2 heterojunction can be regulated from a type-II heterojunction to a Schottky junction, showing a tunable built-in electric field at the heterojunction interface. This resulted in the dynamic switch of carrier transport and photoresponse in the heterojunction. With this dual-mode function, the new photodetector can have both a high detectivity and a large responsivity, surpassing the current performance of single mode 2D TMDs photodetectors. With a direct laser writing and erasing technique, the photoresponse of a WSe2/VO2 device can be locally modulated as desired. This dual mode detection of the WSe2/VO2 photodetector deepens the fundamental understanding of charge transfer in heterojunctions and favors versatile applications in photodetection.
关键词： Photodetectors,Phase-transition,2D materials,WSe2/VO2 heterojunction,Dual-mode
更新于2025-09-12 10:27:22