Hybrid Photodetector Research Articles

Electric field assisted sintering to improve the performance of nanostructured dye sensitized solar cell (DSSC)

Herein, we report the application of electric field assisted sintering (EFAS) procedure in dye sensitized solar cells (DSSCs). The EFAS process improved DSSC performance by enhancing optical and electrical characteristics simultaneously. The EFAS procedure is shown to be capable of reducing the TiO2 nanoparticle aggregation leading to the higher surface area for dye molecules adsorbates. Lower nanoparticle aggregation can be evidently observed by field emission scanning electron microscopy imaging. By applying an external electric field, the current density and conversion efficiency improved significantly about 30% and 45%, respectively. UV-Visible spectra of the desorbed dye molecules on the porous nanoparticles bedding confirm a higher amount of dye loading in the presence of an external electric field. Correspondingly, comprehensive J-V characteristics modeling reveals the enhancement of the diffusion coefficient by EFAS process. The proposed method can be applied to improve the efficiency of the mesostructured hybrid perovskite solar cells, photodetectors, and quantum dot-sensitized solar cells, as well as reduction of the surface area loss in all porous media.

Microsecond resolved single-molecule FRET time series measurements based on the line confocal optical system combined with hybrid photodetectors.

Single-molecule (sm) fluorescence time series measurements based on the line confocal optical system are a powerful strategy for the investigation of the structure, dynamics, and heterogeneity of biological macromolecules. This method enables the detection of more than several thousands of fluorescence photons per millisecond from single fluorophores, implying that the potential time resolution for measurements of the fluorescence resonance energy transfer (FRET) efficiency is 10 μs. However, the necessity of using imaging photodetectors in the method limits the time resolution in the FRET efficiency measurements to approximately 100 μs. In this investigation, a new photodetector called a hybrid photodetector (HPD) was incorporated into the line confocal system to improve the time resolution without sacrificing the length of the time series detection. Among several settings examined, the system based on a slit width of 10 μm and a high-speed counting device made the best of the features of the line confocal optical system and the HPD. This method achieved a time resolution of 10 μs and an observation time of approximately 5 ms in the sm-FRET time series measurements. The developed device was used for the native state of the B domain of protein A.

Applications of a hybrid photodetector (HPD) to biological fluorescence microscopes and wide-field fluorescence detection of mobile single biomolecules with high temporal resolution using an HPD

Applications of a hybrid photodetector (HPD) to biological fluorescence microscopes and wide-field fluorescence detection of mobile single biomolecules with high temporal resolution using an HPD

Wide channel broadband CH3NH3PbI3/SnS hybrid photodetector: breaking the limit of bandgap energy operation.

Perovskite-based hybrid organic–inorganic devices have recently demonstrated high potential in optoelectronics. Yet, the preparation of perovskite-based photodetectors over a desired scale without any complex architecture is still challenging. Herein, we proposed a new CH3NH3PbI3/SnS hybrid planar broadband (365 to 850 nm) photodetector, having a wide channel length of 6 mm. The growth of the device was studied by utilizing scanning electron microscopy, energy-dispersive X-ray mapping, X-ray diffraction, and optical spectroscopies. Furthermore, the efficient charge transfer from CH3NH3PbI3 to SnS was confirmed by employing time-correlated single photon counting. The pure SnS device generates 0.05 μA photocurrent at 365 nm, 4 mW cm−2, which is notably enhanced 140 times after embedding with CH3NH3PbI3. Further, the hybrid device shows a significant photoresponse even below the band gaps of individual CH3NH3PbI3 or SnS, which matches well with the density functional theory prediction. The observed results will create new opportunities to develop and design a low-cost, broadband, and efficient photodetector over a chosen horizontal area.

A broad-spectral-response perovskite photodetector with a high on/off ratio and high detectivity

We designed and fabricated a CH3NH3PbI3/TiO2/Si hybrid photodetector, which shows a high on/off ratio, high detectivity and broad photoresponse.

Broadband hybrid organic/CuInSe2 quantum dot photodetectors

A broadband hybrid photodetector was obtained by combining the ultraviolet detection of spiro-OMeTAD and near-infrared detection of CuInSe2 QDs.

Tuning the spectral response of ultraviolet organic-inorganic hybrid photodetectors via charge trapping and charge collection narrowing.

Organic-inorganic hybrid ultraviolet photodetectors with tunable spectral response are desirable for many different applications. In this work, we blended poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) with ZnO nanoparticles in weight ratios of 1 : 1 and 2 : 1 to create charge traps within the active layers for devices with the conventional structure ITO/PEDOT : PSS/PTAA : ZnO/BCP/Al. Thin (150-200 nm) and thick (1400-1900 nm) active layers were employed to utilize charge collection narrowing (CCN). Both thickness and composition of the active layer impacted the spectral tunability of the photoresponse. A single narrow response peak centered at 420 nm (the PTAA absorption edge) with a full width at half maximum of 12 nm was achieved from the device with a 1900 nm active layer and PTAA : ZnO weight ratio of 1 : 1. Decreasing the active layer thickness to 150 nm resulted in a broad spectral response between 320-420 nm with an external quantum efficiency (EQE) value of 295% under 350 nm illumination and a -1 V bias, exhibiting photomultiplication via charge trapping and injection even at small reverse biases. Increasing the weight ratio of PTAA : ZnO to 2 : 1 lowered both the dark current and photocurrent, eliminated photomultiplication in the thin device, and diminished the efficacy of CCN to narrow the spectral photoresponse in the thick device. Transfer matrix method (TMM) and 3-dimensional finite-difference time-domain (3D-FDTD) simulations were performed to understand the impact of thickness and composition of the active layer on the spectral response of UV photodetectors in terms of exciton generation rate and electric field distribution within the devices.

In situ formation of CsPbBr3/ZnO bulk heterojunctions towards photodetectors with ultrahigh responsivity

A solution-processed hybrid photodetector based on in situ formed CsPbBr3/ZnO bulk heterojunctions exhibited ultrahigh responsivity, long-term stability and desirable imaging capability.

2D MoS2–carbon quantum dot hybrid based large area, flexible UV–vis–NIR photodetector on paper substrate

While all reports on 2D–0D hybrid photodetectors are on silicon substrate and based on heavy metals quantum dots exhibiting limited range detection, this paper is the first demonstration of 2D MoS2–carbon quantum dot (CQD) based flexible broadband photodetector (PD) wherein MoS2 was grown on cellulose paper using hydrothermal method and CQD was synthesized using a low cost, one step pyrolytic process of chia seeds. The absorbance of CQD in UV region combined with the broadband absorption of MoS2 in visible and NIR region broadens the absorbance range. Structural characterization revealed few layered MoS2 and CQD to be in the range of 2–6nm. Responsivity for the fabricated sensor was found to be 8.4, 2.62 and 18.12mA/W in UV, NIR and visible region respectively which are comparable and even better compared to photodetector fabricated using sophisticated cleanroom techniques. The PD showed negligible variation in photoresponse under repeated (up to 500 cycles) bending conditions. Discrete distribution of CQD over MoS2 creates unipolar junctions which helps in generation of small local electric fields thereby increasing the sensitivity of the sensor. The work presented here is a major step ahead in fabrication of low-cost flexible broadband photodetectors which finds potential applications in the field of flexible and wearable electronics, security and surveillance systems, etc.

Generalized Scheme for High Performing Photodetectors with a p-Type 2D Channel Layer and n-Type Nanoparticles.

A generalized scheme for the fabrication of high performance photodetectors consisting of a p-type channel material and n-type nanoparticles is proposed. The high performance of the proposed hybrid photodetector is achieved through enhanced photoabsorption and the photocurrent gain arising from its effective charge transfer mechanism. In this paper, the realization of this design is presented in a hybrid photodetector consisting of 2D p-type black phosphorus (BP) and n-type molybdenum disulfide nanoparticles (MoS2 NPs), and it is demonstrated that it exhibits enhanced photoresponsivity and detectivity compared to pristine BP photodetectors. It is found that the performance of hybrid photodetector depends on the density of NPs on BP layer and that the response time can be reduced with increasing density of MoS2 NPs. The rising and falling times of this photodetector are smaller than those of BP photodetectors without NPs. This proposed scheme is expected to work equally well for a photodetector with an n-type channel material and p-type nanoparticles.

Nanocrystalline Perovskite Hybrid Photodetectors with High Performance in Almost Every Figure of Merit

AbstractConversion of photon into electron is a phenomenon of great importance in nature. Photodetectors based on this principle have immense potential applications at the frontiers of both scientific and industrial communities, thus affecting the daily life. Herein, a novel class of high‐quality organic–inorganic trihalide perovskite nanoscale hybrid photodetectors is presented based on carbon electrode−molecule junctions working at mild conditions. Almost every figure of merit with high performance, such as highest responsivity, highest photogain, high detectivity, high linear dynamic range, and a broad spectral response, could be achieved simultaneously in a single device under different biases. These significant achievements benefit from rational choices of novel energy loss‐prevented hybrid perovskite nanocrystals as active materials and optimized carbon electrode−molecule junctions as device architectures, which leads to a hybridization mechanism of photodiodes and photoconductors. These investigations demonstrate a useful photodetector platform that might lead to many future photoelectric conversion applications in the practical way.

Development of a new 2-inch hybrid photo-detector using MPPC

We have newly developed a Hybrid Photo-Detector (HPD) with 2-inch diameter. It consists of a bialkali photocathode and a 3 mm x 3 mm Multi-Pixel-Photon Counter (MPPC) sealed in a glass tube. The electric field inside the tube is designed so that photoelectrons emitted from the photocathode are collected in the MPPC, where photoelectrons are amplified. For conventional HPDs with an avalanche diode, extremely high voltage such as -8kV has to be provided to achieve gain sufficient for single photon detection. However, our HPD with MPPC has single photon sensitivity only with lower voltage like PMTs due to high gain of MPPC. In addition, this device can cover larger area with only one MPPC. These features enable us to easily handle high performance HPD in various applications, such as high energy physics, biomedical field etc. This test sample was produced in 2016, and we have checked its basic characteristics. The peak photocathode quantum efficiency was found to be very high of 37% at the wavelength of 340 nm. We have confirmed that HPD with MPPC has capability of single photon detection in low operation voltage less than -2 kV. This report will present detailed performance studies of this sample.

Synthesis of silver nanowires towards the development the ultrasensitive AgNWs/SiNPLs hybrid photodetector and flexible transparent conductor

In this paper, we report the synthesis of silver nanowires (AgNWs) via polyol method towards the fabrication of low cost high sensitive hybrid photodetector. During AgNWs synthesis, NaCl was added to the reaction for controlling the free Ag+ ions concentration during the formation of initial Ag seeds. Field emission scanning electron microscopy results show that AgNWs of diameter ~ 50–80nm and length ~ 5–30µm can be achieved. UV–Visible absorption spectroscopy and energy dispersive spectroscopy results indicate the formation of AgNWs in highly pure phase. Hybrid detector was fabricated by depositing the AgNWs film on silicon nanopillar (SiNPLs) substrate. Fabricated hybrid AgNWs/SiNPLs photodetector exhibits ~ 10 times more sensitivity as compared to SiNPLs based detector. In addition, AgNWs/SiNPLs detector shows outstanding stability against 20 days exposure to ambient conditions. These results indicate that AgNWs can be utilized to fabricate the high performance one dimensional hybrid photodetectors. The effectiveness of AgNWs to make the transparent flexible devices has also been demonstrated. AgNWs film deposited on a flexible polyethylene terephthalate (PET) substrate revealed a maximum total transmittance and sheet resistance of ~ 94% and ~ 200/sq., respectively.

Enhanced performance of solution-processed broadband photodiodes by epitaxially blending MAPbBr3 quantum dots and ternary PbSxSe1−x quantum dots as the active layer

Organic–inorganic hybrid photodetectors attract more and more interest, since they can combine the advantages of both organic and inorganic materials into one device, and broadband photodetectors are widely used in many scientific and industrial fields. In this work, we demonstrate the enhanced-performance solution-processed broadband photodiodes by epitaxially blending organo-lead halide perovskite (MAPbBr3) colloidal quantum dots (CQDs) with ternary PbSxSe1−x CQDs as the active layer. As a result, the interfacial features of the hetero-epitaxial nanocomposite MAPbBr3:PbSxSe1−x enables the design and perception of functionalities that are not available for the single-phase constituents or layered devices. By combining the high electrical transport properties of MAPbBr3 QDs with the highly radiative efficiency of PbS0.4Se0.6 QDs, the photodiodes ITO/ZnO/PbS0.4Se0.6:MAPbBr3/Au exhibit a maximum photoresponsivity and specific detectivity of 21.48 A W−1 and 3.59 × 1013 Jones, 22.16 A W−1 and 3.70 × 1013 Jones at room temperature under 49.8 μW cm−2 532 nm laser and 62 μW cm−2 980 nm laser, respectively. This is higher than that of the layered photodiodes ITO/ZnO/PbS0.4Se0.6/MAPbBr3/Au, pure perovskite (MAPbBr3) (or PbS0.4Se0.6) QD-based photodiodes reported previously, and it is also better than the traditional inorganic semiconductor-based photodetectors. Our experimental results indicate that epitaxially-aligned nanocomposites (MAPbBr3:PbSxSe1−x) exhibit remarkable optoelectronic properties that are traceable to their atomic-scale crystalline coherence, and one can utilize the excellent photocarrier diffusion from PbSxSe1−x into the perovskite to enhance the device performance from the UV-visible to infrared region.

High-performance and flexible photodetectors based on P3HT/CdS/CdS:SnS2 superlattice nanowires hybrid films

Flexible photodetectors based on organic–inorganic hybrid materials have been attracted great interests because of their unique performance and potential applications. In this study, a novel hybrid photodetector has been constructed on SiO2/Si substrate using organic poly (3-hexylthiophene) (P3HT) and inorganic CdS/CdS:SnS2 superlattice nanowires (CCS SNs). Compared with pure P3HT device, the as-constructed hybrid devices exhibit a prominent photoresponse, as well as excellent photoswitch effect and repeatability due to the interactions of the photogenerated charge carriers and the interface trap sites. In addition, flexible hybrid photodetectors based on the P3HT/CCS SNs hybrid films are prepared on paper substrates, which present a high responsivity of 244 A/W, a remarkable ratio of photocurrent and dark current of 1.25 × 103, a fast response time of 12 ms, a noteworthy detectivity of 8.7 × 1012 Jones, and good reproducibility. More importantly, the photocurrent and responsivity of our paper-based hybrid device decline 9% after 200 cycles of bending, revealing high mechanical flexibility and electrical stability. Therefore, the high-performance and flexible photodetectors based on the P3HT/CCS SNs hybrid films presented in this work will have been attracted great attention as its potential application in future portable and flexible electronics.

Photodetectors based on sensitized two-dimensional transition metal dichalcogenides—A review

Abstract

Lateral Graphene-Contacted Vertically Stacked WS2 /MoS2 Hybrid Photodetectors with Large Gain.

A demonstration is presented of how significant improvements in all-2D photodetectors can be achieved by exploiting the type-II band alignment of vertically stacked WS2 /MoS2 semiconducting heterobilayers and finite density of states of graphene electrodes. The photoresponsivity of WS2 /MoS2 heterobilayer devices is increased by more than an order of magnitude compared to homobilayer devices and two orders of magnitude compared to monolayer devices of WS2 and MoS2 , reaching 103 A W-1 under an illumination power density of 1.7 × 102 mW cm-2 . The massive improvement in performance is due to the strong Coulomb interaction between WS2 and MoS2 layers. The efficient charge transfer at the WS2 /MoS2 heterointerface and long trapping time of photogenerated charges contribute to the observed large photoconductive gain of ≈3 × 104 . Laterally spaced graphene electrodes with vertically stacked 2D van der Waals heterostructures are employed for making high-performing ultrathin photodetectors.

Colloidal CdSe Quantum Dots and PQT-12-Based Low-Temperature Self-Powered Hybrid Photodetector

In this letter, a novel dual junction self-powered hybrid photodetector is proposed using colloidal CdSe quantum dots (QDs) as an active layer (~50-nm thickness), and PQT-12 polymer as filter layer subsequently deposited on an ITO-coated glass substrate by the spin coating method. The colloidal CdSe QDs are deposited on the PQT-12 film at 80 °C, which is much smaller than the growth temperature (usually >300 °C) of the inorganic layer of other reported hybrid self-powered detectors. The Au metal dots are deposited on the CdSe QD layer for anode electrodes while the ITO acts as the cathode electrode of the device. Two asymmetric depletion widths formed at PQT-12/CdSe and Au/CdSe junctions at two sides of the active layer controls the operation of the proposed detector. The photodetector shows band-pass response over the visible spectrum with a sharp cutoff for higher wavelengths at ~610 nm. The maximum responsivity and detectivity of the self-powered photodetector are achieved to be ~3.3 mA/W and $5.4\times 10^{9}$ cmHz $^{1/2}\text{W}^{-1}$ , respectively, at a wavelength of ~420 nm under the optical power density of $\sim 130\mu \text{W}$ /cm2. The rise time and fall time of the device are found to be ~12.01 and ~15.32 ms, respectively.

Self‐Powered UV Photodetector Array Based on P3HT/ZnO Nanowire Array Heterojunction

AbstractSelf‐powered photodetector array based on organic–inorganic heterojunction is extremely suitable for light imaging applications, owing to their unique flexibility and stability. Here, a self‐powered ultraviolet (UV) photodetector based on p‐P3HT/n‐ZnO nanowire array heterojunction is demonstrated, which exhibits photoconductive gain of 4.2 × 10−4, responsivity of 125 µA W−1, specific detectivity of 3.7 × 107 Jones, and response/recovery speed of less than 100 ms at a low light intensity of 0.84 mW cm−2 for λ = 365 nm. The responsivity of this photodetector can be further enhanced by ≈21.9% under a temperature difference of −15.4 °C, owing to the thermo‐phototronic effect. Moreover, a photodetector array with 16 pixels is successfully demonstrated for light imaging of complex patterns, such as number‐shape and cross‐shape. This study provides a practical solution to achieve large‐scale UV imaging by integrating inorganic–organic hybrid photodetector into self‐powered array configuration.

Electrochemical half-reaction-assisted sub-bandgap photon sensing in a graphene hybrid phsotodetector

The photogating effect has been previously utilized to realize ultra-high photoresponsivity in a semiconductor-graphene hybrid photodetector. However, the spectral response of the graphene hybrid photodetector was limited by the bandgap of the incorporated semiconductor, which partially compromised the broadband absorption of graphene. Here, we show that this limitation can be overcome in principle by harnessing the electron-accepting ability of the electrochemical half-reaction. In our new graphene phototransistor, the electrochemical half-reaction serves as an effective reversible electron reservoir to accept the photoexcited hot electron from graphene, which promotes the sub-bandgap photosensitivity in a silver chloride (AgCl)-graphene photodetector. The photoconductive gain of ~ 3 × 109 electrons per photon in the AgCl-graphene hybrid is favored by the long lifetime of photoexcited carriers in the chemically reversible redox couple of AgCl/Ag0, enabling a significant visible light (400–600 nm) responsivity that is far beyond the band-edge absorption of AgCl. This work not only presents a new strategy to achieve an electrically tunable sub-bandgap photoresponse in semiconductor-graphene heterostructures but also provides opportunities for utilizing the electrochemical half reaction in other two-dimensional systems and optoelectronic devices.