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- 实验方案
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Understanding the mechanisms of a conjugated polymer electrolyte for interfacial modification in solution-processed organic-inorganic hybrid perovskite photodetectors
摘要： Interfacial modification is an effective strategy to suppress the dark current in photodetectors for performance improvements. Here, solution-processed conjugated polymer electrolyte poly[(9,9-bis(3’-(N,N-dimethylamino) propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)](PFN), widely used for interface engineering in organic and perovskite solar cells, is introduced to the photovoltaic photodetectors based on α-phase formamidinium lead iodide (α-FAPbI3) perovskite at cathode interfaces. The PFN layer has both positive and negative impacts on the overall device performances. The steady-state device parameters including external quantum efficiency, photoresponsivity, and detectivity are enhanced because the dark current is effectively suppressed due to the hindered hole injection by the PFN layer. However, the incorporation of PFN leads to different transient photocurrent dynamics with a peak after turn-on and a long-lived tail after turn-off, increasing the fall time, although it has little impact on the rise time. The proposed mechanisms involve the trapping and detrapping effects of accumulated photogenerated electrons at the electron-transporting layer/PFN interface, which are proved by capacitance-voltage measurements and impedance spectroscopy analysis. Our results have important significance for understanding the different effects and mechanisms of conjugated polymer electrolytes for interfacial engineering in photodetectors and solar cells and selecting suitable interfacial materials for electrode modification in photodetectors.
关键词： Conjugated polymer electrolyte,Transient photocurrent dynamics,Steady-state device parameters,α-FAPbI3 perovskite photodetectors,Interfacial modification
更新于2025-09-23 15:21:01
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Fabrication of bifacial sandwiched heterojunction photoconductor a?? Type and MAI passivated photodiode a?? Type perovskite photodetectors
摘要： In this work, we report novel heterojunctions perovskite photodetector architecture utilizing metal-free contact electrodes. The metal-free contact electrodes were exploited to fabricate photoconductor – type perovskite photodetector. The attempt to investigate the effect of passivating the active layers of the as – proposed architecture with electrolytic MAI gave rise to a photodiode – type perovskite photodetector. These two photodetector types are sensitive and responsive to light sources through their dual transparent electrodes faces (N-face and T-face). We also showed that passivating the surfaces of the sandwiched perovskite layers with MAI solution improves the performance of the fabricated photodetectors, where the detectivity is enhanced by a factor of hundred compared to non-passivated devices. The proposed photodetectors architectures demonstrate champion dual-detectivity (1.77×1014 Jones for N-face and 4.64 × 1014 Jones for T-face), dual-responsivity (1.94 × 103 A/W for N-face and 1.61 × 103 A/W for T-face) and high dual – sensitivity (3.3 × 102 for N-face and 1.1 × 102 for T-face). All these properties were obtained from the two faces of the MAI passivated photodetectors under 0.02 mW/cm2 red LED illumination and at -2.0 bias voltage. This novel architecture may scale up towards building energy and cost efficient classes of optoelectronic and photovoltaic devices which are responsive to light in two directions.
关键词： MAI Passivation,Bifacial,Photoconductor,Perovskites,Photodetectors,Photodiode
更新于2025-09-23 15:21:01
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Characterization of a Time-Resolved Diffuse Optical Spectroscopy Prototype Using Low-Cost, Compact Single Photon Avalanche Detectors for Tissue Optics Applications
摘要： Time-resolved diffuse optical spectroscopy (TR-DOS) is an increasingly used method to determine the optical properties of diffusive media, particularly for medical applications including functional brain, breast and muscle measurements. For medical imaging applications, important features of new generation TR-DOS systems are low-cost, small size and efficient inverse modeling. To address the issues of low-cost, compact size and high integration capabilities, we have developed free-running (FR) single-photon avalanche diodes (SPADs) using 130 nm silicon complementary metal-oxide-semiconductor (CMOS) technology and used it in a TR-DOS prototype. This prototype was validated using assessments from two known protocols for evaluating TR-DOS systems for tissue optics applications. Following the basic instrumental performance protocol, our prototype had sub-nanosecond total instrument response function and low differential non-linearity of a few percent. Also, using light with optical power lower than the maximum permissible exposure for human skin, this prototype can acquire raw data in reflectance geometry for phantoms with optical properties similar to human tissues. Following the MEDPHOT protocol, the absolute values of the optical properties for several homogeneous phantoms were retrieved with good accuracy and linearity using a best-fitting model based on the Levenberg-Marquardt method. Overall, the results of this study show that our silicon CMOS-based SPAD detectors can be used to build a multichannel TR-DOS prototype. Also, real-time functional monitoring of human tissue such as muscles, breasts and newborn heads will be possible by integrating this detector with a time-to-digital converter (TDC).
关键词： diffuse optical spectroscopy,time-resolved spectroscopy,tissue optics,single-photon avalanche diode,silicon photodetectors,time-correlated single-photon counting
更新于2025-09-23 15:21:01
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Efficiency and spectral performance of narrowband organic and perovskite photodetectors: a cross-sectional review
摘要： The capability of detecting visible and near infrared light within a narrow wavelength range is in high demand for numerous emerging application areas, including wearable electronics, the Internet of Things, computer vision, artificial vision and biosensing. Organic and perovskite semiconductors possess a set of properties that make them particularly suitable for narrowband photodetection. This has led to rising interest in their use towards such functionality, and has driven remarkable progress in recent years. Through a comparative analysis across an extensive body of literature, this review provides an up-to-date assessment of this rapidly growing research area. The transversal approach adopted here focuses on the identification of: (a) the unifying aspects underlying organic and perovskite narrowband photodetection in the visible and in the near infrared range; and (b) the trends relevant to photoconversion efficiency and spectral width in relation to material, device and processing strategies. A cross-sectional view of organic and perovskite narrowband photodetection is thus delineated, giving fresh insight into the status and prospects of this research area.
关键词： narrowband organic photodetectors,narrowband perovskite photodetectors,NIR photodetectors,colour sensors,spectral selectivity
更新于2025-09-23 15:19:57
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Narrowbanda??Absorptiona??Type Organic Photodetectors for the Fara??Red Range Based on Fullerenea??Free Bulk Heterojunctions
摘要： Spectrally-selective photodetection via organic semiconductors manifesting narrowband absorption (NBA photodetection) is highly attractive for emerging applications that require ultrathin, lightweight, and low-cost solutions. While successful over mainstream color bands, NBA photodetectors have struggled so far to meet the functional and/or performance demands at longer wavelengths, importantly in the far-red (700–750 nm), a range relevant to diverse applications in analytical biology, medical diagnostics, remote sensing, etc. In consideration of the potential of a nonfullerene-acceptor route to address this challenge, the narrowband photodetection capabilities of SBDTIC, a recently-developed benzodithiophene-based acceptor with narrowband absorption in the far-red, are explored. Two bulk-heterojunction NBA configurations are considered, in which SBDTIC is combined with a donor either absorbing also in the far-red, or transparent through the visible. It is found that the latter configuration provides superior narrowband functionality, with peak detectivity of 1.42 × 1013 Jones and spectral width of 141 nm—the highest detectivity to date for NBA far-red-selective photodetectors, and the smallest spectral width of all solution-processed implementations. In self-powered operation, such photodetectors additionally present a quasilinear response over a photocurrent range of least four orders of magnitude, and respond in the microsecond range, further evidencing the suitability of this approach to address the wealth of target applications.
关键词： far-red,nonfullerene acceptors,narrowband-absorption photodetectors,organic photodetectors,narrowband photodetectors
更新于2025-09-23 15:19:57
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Photodetectors based on solution-processable semiconductors: Recent advances and perspectives
摘要： The detection of light, one of the most important technologies, has widespread applications in industry and our daily life, e.g., environmental monitoring, communications, surveillance, image sensors, and advanced diagnosis. Along with the remarkable progress in the field of organics, those based on quantum dots, and recently emerged perovskite optoelectronics, photodetectors based on these solution-processable semiconductors have shown unprecedented success. In this review, we present the basic operation mechanism and the characterization of the performance metrics based on these novel materials systems. Then, we focus on the current research status and recent advances with the following five aspects: (i) spectral tunability, (ii) cavity enhanced photodetectors, (iii) photomultiplication type photodetectors, (iv) sensitized phototransistors, and (v) ionizing radiation detection. At the end, we discuss the key challenges facing these novel photodetectors toward manufacture and viable applications. We also point out the opportunities, which are promising to explore and may require more research activities.
关键词： sensitized phototransistors,photodetectors,cavity enhanced photodetectors,solution-processable semiconductors,photomultiplication type photodetectors,spectral tunability,ionizing radiation detection
更新于2025-09-23 15:19:57
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Solutiona??Processed Flexible Broadband Photodetectors with Solutiona??Processed Transparent Polymeric Electrode
摘要： Room-temperature solution-processed flexible photodetectors with spectral response from 300 to 2600 nm are reported. Solution-processed polymeric thin film with transparency ranging from 300 to 7000 nm and superior electrical conductivity as the transparent electrode is reported. Solution-processed flexible broadband photodetectors with a 'vertical' device structure incorporating a perovskite/PbSe quantum dot bilayer thin film based on the above solution-processed transparent polymeric electrode are demonstrated. The utilization of perovskite/PbSe quantum dot bilayer thin film as the photoactive layer extends spectral response to infrared region and boosts photocurrent densities in both visible and infrared regions through the trap-assisted photomultiplication effect. Operated at room temperature and under an external bias of -1 V, the solution-processed flexible photodetectors exhibit over 230 mA W-1 responsivity, over 1011 cm Hz1/2/W photodetectivity from 300 to 2600 nm and ≈70 dB linear dynamic ranges. It is also found that the solution-processed flexible broadband photodetectors exhibit fast response time and excellent flexibility. All these results demonstrate that this work develop a facile approach to realize room-temperature operated ultrasensitive solution-processed flexible broadband photodetectors with 'vertical' device structure through solution-processed transparent polymeric electrode.
关键词： perovskite photodetectors,broadband photodetectors,PbSe quantum dots,flexible electronics
更新于2025-09-23 15:19:57
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Narrowband colloidal quantum dot photodetectors for wavelength measurement applications
摘要： High performance photodetectors based on colloidal quantum dots have been demonstrated in a wide spectral range spanning from the visible to the mid infrared. Quantum dot photodetectors typically show a low-pass type spectral response with a tunable cutoff wavelength. In this paper, we propose a method for the realization of narrowband photodetectors based on the combination of photoconductors and optical filters, both realized with colloidal PbS quantum dots. We demonstrate that an array of such narrowband photodetectors can be effectively employed for the realization of a compact wavemeter operating in the visible and near-infrared spectral range.
关键词： Narrowband photodetectors,Wavelength meter,Colloidal Quantum Dots photodetectors
更新于2025-09-23 15:19:57
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Hybrid Nanostructures of 2D CdSe Nanoplatelets for High-Performance Photodetector Using Charge Transfer Process
摘要： Two-dimensional (2D) semiconductor colloidal nanoplatelets (NPLs) have shown great potential as light-harvesting materials due to their advanced optical properties. Here, we have designed hybrid nanostructures of 2D CdSe nanoplatelets with phenothiazine (PTZ) for high-performance photodetector with varying thickness of CdSe NPLs by controlling charge transfer process. Significant photoluminescence quenching and the shortening of the average decay time of CdSe NPLs in presence of PTZ reveal the charge transfer process. Transient absorption (TA) spectroscopic analysis reveals the hot carrier cooling dynamics varies with changing the thickness of monolayers (ML) of CdSe NPLs. Furthermore, the slow exciton recombination of CdSe NPLs in presence of PTZ indicates the efficient charge separation. The optimized CdSe NPLs-PTZ hybrid exhibits a significant enhancement of photocurrent (~4.7×103 fold photo-to-dark current ratio) as compared to pure 3 ML CdSe NPLs (~10 fold) at the applied voltage of 1.5V. The measured external quantum efficiency, maximum detectivity and response time for the optimized hybrid are found to be ~40%, 4×1011 Jones and 107 milliseconds, with the responsivity value of 160 mA/W. These highly efficient measured parameters clearly suggest that CdSe NPLs-PTZ hybrid systems are promising alternate for ultrasensitive photodetector.
关键词： 2D colloidal nanoplatelets,photodetectors,hole transfer,hybrids,photocurrent
更新于2025-09-23 15:19:57
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Improving the performance of ultra-flexible perovskite photodetectors through cation engineering
摘要： High performance ultra-flexible lightweight perovskite photodetectors hold promising applications on arbitrary substrates include unmanned aerial vehicles. Herein, we report a facile method to improve the performances of perovskite photodetectors on flexible ultrathin (50 μm) polyimide substrates by tuning the composition with different ratios of cations. In the presence of lead thiocyanate, a certain amount of formamidinium introduction could sufficiently enhance the methylammonium lead triiodide perovskite film quality with prolonged carrier lifetime. Perovskite photodetector with response time of ton=89 ms and toff=47 ms is achieved with a very simple device architecture. In addition, our flexible photodetectors maintain good performances after rigorous folding and bending, demonstrating excellent mechanical properties, which can be very useful for a variety of applications.
关键词： compositional engineering,mechanical stability,ultra-flexible detectors,perovskite photodetectors
更新于2025-09-23 15:19:57