- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Highly sensitive, broadband, fast response organic photodetectors based on semi-tandem structure
摘要： Solution-processed organic photodetectors (OPDs) simultaneously integrating high performance by solution-processability. The semi-tandem structure directly superimposes two active layers with complementary absorption spectra, achieving a broad spectral response of 300-1000 nm. It provides a detection covering from ultraviolet to near-infrared range, while the external quantum efficiency in the spectral range of 550 nm to 950 nm retains 70 %. The high electron and hole injection barriers enable a dark current density as low as 6.51×10-5 mA cm-2 at -0.1 V, resulting in a noise current of 3.91×10-13 A Hz-1/2 at 70 Hz, which is nearly three times lower than single-junction photodetectors. Encouragingly, the device response speed is improved by suppressing the resistance-capacitance time constant of the device employing semi-tandem structure induced capacitance decreasing. The state-of-the-art OPDs contribute to the response time of 26.27 ns, which is the fastest one in OPDs to the best of our knowledge. We believe that the semi-tandem structures provide a new approach to achieving high-performance photodetectors integrating fast, sensitive and broadband response.
关键词： broadband,ultra-fast response,Organic photodetectors,semi-tandem structure
更新于2025-09-23 15:19:57
-
Reducing current fluctuation of Cs3Bi2Br9 perovskite photodetectors for diffuse reflection imaging with wide dynamic range
摘要： Recently, the newly booming metal halide perovskites have attracted extensive attention worldwide due to their outstanding optoelectronic performance, and are expected to be ideal candidates for photodetectors (PDs). However, there is still lack of perovskite PDs-based imaging devices coming into commercialization stage, due to some practical reasons including toxicity brought by lead-based perovskites and the large light current fluctuations. In this paper, for the first time we fabricate a lead-free Cs3Bi2Br9 perovskite PD, and build a prototype of this perovskite PD-based imaging system with diffuse reflection imaging mode. Moreover, we propose a new parameter F related to light current fluctuation to evaluate imaging performance of a PD especially for weak diffuse light condition, and prove its usability by comparison of unoptimized lead-free Cs3Bi2Br9 perovskite PD and atomic layer deposition (ALD) optimized Cs3Bi2Br9 PD. ALD-optimization can improve the quality of perovskite film and suppress the dark current and current fluctuation. Finally, we obtain satisfactory diffuse reflection images of 2D and 3D objects with wide dynamic range. Therefore, the ALD-optimized Cs3Bi2Br9 PD has addressed two major concerns about perovskite PDs-based imaging devices, that may extend application of perovskite materials and improve imaging quality.
关键词： Current fluctuations,Photodetectors,Diffuse reflection imaging,Cs3Bi2Br9 perovskites
更新于2025-09-23 15:19:57
-
Reducing the Dark Current of Cuprous Oxide/Au Schottky Photodetector for High Signal-to-noise Ratio Imaging
摘要： Photodetectors (PDs) as image sensors have been widely used in imaging system due to their outstanding photosensitivity. The improvement of imaging quality (signal-to-noise ratio, SNR) can be realized by reducing the dark current of PDs. Conventionally, interfacial engineering can effectively suppress the dark current of PDs. Nevertheless, these techniques are hard to be applied in practical imaging systems owing to their complicated process. In this work, we proposed a facile method to reduce the dark current of Cu2O/Au Schottky PDs, and further demonstrated its application in high SNR imaging system. By applying a small external bias of -120 μV, the dark current of PDs decreases from 27 nA to 0.6 nA, with 4023% improvements of ON/OFF ratio. Additonaly, a model based on free carriers generated by rich trap-state and thermal excitation under asymmetric internal electric field was proposed to understand this phenomenon. Finally, a high-resolution image with high SNR (48 dB) was acquired, which is close to that of commercial Si-CDD and CMOS. Our results provide a convenient way to reduce the dark current and improve the image quality, also suggest Cu2O is potentially an attractive candidate to be applied in optical imaging applications.
关键词： SNR,dark current,photodetectors,imaging,Cu2O/Au Schottky
更新于2025-09-23 15:19:57
-
Laser Annealing Enhanced the Photophysical Performance of Pt/n-PSi/ZnO/Pt-Based Photodetectors
摘要： Herein, the effect of pulsed Nd:YAG laser irradiation at different fluencies in air at room temperature on the performance of n-PSi/ZnO-based UV MSM photodetector was demonstrated. Thermal and photon energies were coupled to synthesize n-PSi/ZnO NCs heterojunctions. The porous silicon (PSi) films with nano-sized pore arrays were first prepared via photoelectrochemical etching (PECE) of n-type silicon wafers with 45 mA/cm2 current density for a duration of 30 min. This was followed by radio frequency sputtering (RFS) of ZnO on PSi at 700 oC and irradiating with a Nd: YAG laser pulses with laser fluence of 40 mJ/cm2. X-ray diffraction analysis indicates the formation of ZnO wurtzite hexagonal crystal structure of n-PSi/ZnO NCs, where the crystallite size decreases (96-29 nm) with number of pulses. Field emission electron scanning microscopy and atomic force microscopy reveal porous nanostructure, arrays of nearly spherically shape particles homogeneously distributed on the entire surface where roughness increases (84-139 nm) with number of pulses. Photoluminescence spectroscopy reveals intrinsic band-to-band transition, donor-acceptor pair emission and quenching of the broadband intensity related to improved of crystallinity, meanwhile the band gap energy of the n-PSi/ZnO NCs is found to decrease (3.26 – 3.13 V). The Nd:YAG laser annealing demonstrate a positive effect on the properties of n-PSi/ZnO NCs photodetector, exhibiting very high sensitivity (3772.92) and very short rise and recovery times (0.30 s and 0.26 s).
关键词： Porous silicon,n-PSi/ZnO junction,Nd-YAG laser,photodetectors
更新于2025-09-23 15:19:57
-
Solutiona??Processed Higha??Quality Cesium Lead Bromine Perovskite Photodetectors with High Detectivity for Application in Visible Light Communication
摘要： Cesium lead bromide (CsPbBr3) perovskite photodetectors (PDs) are attractive for applications in visible light communication (VLC) due to ultra-high detectivity and fast response speed. However, the fabrication of high-quality CsPbBr3 polycrystalline films using solution-based process is very challenging. Due to the low solubility of CsBr in precursor solutions, solution-processed CsPbBr3 films are typically discontinuous and porous, hindering the performance of resulting PDs. Herein, a facile and modified sequential spin-coating method is introduced to prepare high-crystallinity, pinhole-free CsPb2Br5-CsPbBr3 perovskite films with an average grain size of ≈1 μm. The hole-transport-layer-free (HTL-free) PDs based on the CsPb2Br5-CsPbBr3 perovskite films show high performance parameters, including the responsivity of 0.11 A W?1, the detectivity of 1.4 × 1012 Jones, a linear dynamic range of 128.6, and an on/off ratio of 1.5 × 106. The PDs outperform other HTL-free perovskite PDs and are comparable to the p–i–n perovskite PDs reported in the literature. In addition, the high-performance CsPb2Br5-CsPbBr3 PDs are applied in VLC by using the PD as a self-powered signal receiver of voice commands in a simulated room. This work uniquely combines the features of high-performance self-powered perovskite PDs with VLC techniques, paving the path to wide applications of all-inorganic perovskite PDs.
关键词： CsPb2Br5-CsPbBr3,perovskites,self-powered photodetectors,visible light communication
更新于2025-09-23 15:19:57
-
MgxZn1a??xO Prepared by the Sola??Gel Method and Its Application for Ultraviolet Photodetectors
摘要： MgxZn1(cid:2)xO (x = 0.05, 0.10, 0.15, and 0.20) ?lms prepared on quartz substrates by the sol–gel method were characterized and studied. According to scanning electron microscopy and x-ray diffraction data, the MgxZn1(cid:2)xO ?lms exhibited a particle-stacking morphology and a hexagonal wurtzite crystal structure. An increase in Mg content led to an obvious increase in particle size. However, a weakening of the hexagonal wurtzite structure was observed and indicated the transition of the MgxZn1(cid:2)xO crystal structure, which was also con?rmed by the Raman spectra results. An increase in bandgap energy from 3.38 eV to 3.55 eV with increased Mg content was determined from the transmittance spectra. Ultraviolet photodetectors based on MgxZn1(cid:2)xO with interdigital electrodes were then fabricated. Dark current as low as 10 pA (corresponding to 5 nA/cm2) under bias of 10 V was achieved. A blueshift of the peak wavelength and cutoff wavelength was observed with increasing Mg content. Noise equivalent power as low as 2 9 10(cid:2)15 W was achieved, detectivity was found to be about 1.2 9 1011 cm Hz1/2/W, and quantum ef?ciency was nearly 100%, which was related to the photoconductive gain.
关键词： sol–gel,bandgap,MgxZn1(cid:2)xO,ultraviolet photodetectors
更新于2025-09-23 15:19:57
-
Photoconducting Devices with Response in the Visiblea??Near-Infrared Region Based on Neutral Ni Complexes of Aryl-1,2-dithiolene Ligands
摘要： Metal bis(1,2-dithiolene) complexes belonging to the class [Ni(Ar-edt)2]x? [Ar-edt2? = arylethylene-1,2-dithiolate; Ar = phenyl, (1x?), 2-naphthyl (2x?); x = 0 and 1] were fully characterized by NMR, UV?visible?near-infrared (UV?vis?NIR), diffuse reflectance, and FT-IR spectroscopy, as well as cyclic voltammetry and single-crystal X-ray diffraction analysis. These complexes have emerged as new photoconducting materials that allowed for the development of a prototype of photodetectors with response in the vis?NIR region. The photodetecting devices showed in some cases quantum efficiencies orders of magnitude higher than those of previously reported 1,2-dithiolene systems.
关键词： vis?NIR region,photoconducting materials,photodetectors,Metal bis(1,2-dithiolene) complexes,quantum efficiencies
更新于2025-09-23 15:19:57
-
In Situ Formed Gradient Bandgapa??Tunable Perovskite for Ultrahigha??Speed Color/Spectruma??Sensitive Photodetectors via Electrona??Donor Control
摘要： Integration of various photodetectors with different light-sensitive materials and detection capacity is an inevitable way to achieve entire color/spectrum detection. However, the uneven capacity of each photodetector would drag the overall performance behind, especially the response speed. A response time down to nanosecond level has not previously been reported for a filter-free color/spectrum-sensitive photodetector, as far as is known. Here, a self-powered filterless color-sensitive photodetection array based on an in situ formed gradient perovskite absorber film with continuously tunable bandgap is demonstrated. Ultrahigh-speed response at nanosecond level is achieved in all the ingredient photodetectors. The junction capacitance being influenced by carrier concentration in the absorber is identified to be responsible for the detection speed. Without any optic or mechanical supporting system, the designed color detector exhibits an external quantum efficiency (EQE) up to 94% and a high spectral resolution of around 80 nm for the whole visible spectrum. This work offers a guidance to achieve fast response of perovskite-based photodetectors from the point of view of carrier-donor control and demonstrates a new avenue to establish color-sensitive photodetectors/spectrometers.
关键词： photodetectors,self-powered devices,color-sensitive photodetection,spectrum analysis,perovskites
更新于2025-09-23 15:19:57
-
High-Performance Germanium Waveguide Photodetectors on Silicon
摘要： Germanium waveguide photodetectors with 4 ??m widths and various lengths are fabricated on silicon-on-insulator substrates by selective epitaxial growth. The dependence of the germanium layer length on the responsivity and bandwidth of the photodetectors is studied. The optimal length of the germanium layer to achieve high bandwidth is found to be approximately 8 ??m. For the 4 × 8 ??m2 photodetector, the dark current density is as low as 5 mA/cm2 at ?1 V. At a bias of ?1 V, the 1550 nm optical responsivity is as high as 0.82 A/W. Bandwidth as high as 29 GHz is obtained at ?4 V. Clear opened eye diagrams at 50 Gbits/s are demonstrated at 1550 nm.
关键词： responsivity,Germanium waveguide photodetectors,silicon-on-insulator substrates,selective epitaxial growth,bandwidth
更新于2025-09-23 15:19:57
-
Enhanced Performances of p-Si/n-ZnO Self-powered Photodetector by Interface State Modification and Pyro-phototronic Effect
摘要： ZnO based self-powered photodetector (PD) has great application potential in distributing sensor networks and internet of things. However, a large number of surface or interface states within ZnO limit its performance improvement. Here, the surface and interface states of ZnO is greatly eliminated by ultraviolet irradiation as an interfacial modification engineering. Reduction of interface states reduces ohmic resistance, also enhances the tuning role of pyro-phototronic effect. And the transient response currents of the self-powered PD are thus significantly improved with a maximal enhancement factor of more than 5900% for the 325-785 nm broadband stimulating beams. The corresponding response time is decreased to few milliseconds or sub-milliseconds. The results indicate that surface-state reduction of ZnO can effectively enhance the modifying role of pyro-phototronic effect and greatly improve the response performances of the self-powered broadband PDs with great application demands in Internet of things, broad spectral detecting and imaging, and smart optoelectronic devices.
关键词： Self-powered,ultraviolet irradiation,interface states,pyro-phototronic effect,broadband photodetectors
更新于2025-09-23 15:19:57