Owning to the unique optical and electronic properties, organic−inorganic hybrid perovskites have made impressive progress in photodetection applications. However, achieving ultrabroadband detection over the ultraviolet (UV) to terahertz (THz) range remains a major challenge for perovskite photodetectors. Here, we report an ultrabroadband (UV−THz) dual-mechanism photodetector based on CH 3 NH 3 PbI 3 films. The photoresponse of the PD in the UV−visible (vis) and near-infrared (NIR)−THz bands is mainly caused by the photoconductive (PC) effect and bolometric effect, respectively. High responsivities ranging from 10 5 to 10 2 mA W −1 are acquired within UV−THz bands under 1 V bias voltage at room temperature. Moreover, the device also shows fast rise and decay times of 76 and 126 ns under 1064 nm laser illumination, respectively. This work provides insight into the thermoelectric characteristics of perovskite and offers a new way to realize ultrabroadband photodetectors notably for THz detector at room temperature.

Platinum was deposited on unintentionally doped n-Al x Ga 1-x N films grown by metal-organic chemical vapor deposition (MOCVD) to form MSM ultraviolet photodetectors. All devices were annealed for 10 min at different temperature in N 2 ambient. Results indicate that the generation of hillocks on the surface of Pt thin-film electrodes at the elevated temperatures due to relieving compressive stress affects the dark current directly. Dark current less than 10pA in the (-10V,10V) range was obtained from a device after annealing at 900 º C. Both detectors show sharp spectral responsivity cutoff of about three orders of magnitude by 325nm and 315nm respectively.

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Ultra-stable broadband photoelectric tunable PbS QD based RRAM device with flexibility and multilevel data storage ability was demonstrated.

Highly sensitive broadband photodetection is of critical importance for many applications. However, it is a great challenge to realize broadband photodetection by using a single device. Here we report photodetectors (PDs) based on three-dimensional (3D) graphene foam (GF) photodiodes with asymmetric electrodes, which show an ultra-broadband photoresponse from ultraviolet to microwave for wavelengths ranging from 10 2 to 10 6    nm . Moreover, the devices exhibit a high photoresponsivity of 10 3    A   · W − 1 , short response time of 43 ms, and 3 dB bandwidth of 80 Hz. The high performance of the devices can be attributed to the photothermoelectric (PTE, also known as the Seebeck) effect in 3D GF photodiodes. The excellent optical, thermal, and electrical properties of 3D GFs offer a superior basis for the fabrication of PTE-based PDs. This work paves the way to realize ultra-broadband and high-sensitivity PDs operated at room temperature.

Vortex beam has attracted much attention for carrying orbital angular momentum (OAM). It has a helical phase structure described by exp (ilθ) and an annular intensity distribution, where l is the topological charge corresponding to the OAM of each photon, and θ is the azimuth angle. [1] Vortex beam is widely used in OAM communications, [2,3] optical tweezers, [4] and quantum information coding. [5,6] In particular, the superposition of OAM states is very significant in metrology, [7,8] quantum science, [6,9] and OAM communications. The superposition of high-order OAM modes can be used for ultra-sensitive angle measurement. [8] In Bose-Einstein condensate, multiple OAM states can also be used to generate arbitrary superpositions of atomic rotation states. [10] Vortex beam carrying OAM has shown promising prospects in increasing the data capacity of communication systems, because multiple orthogonal modes can be transmitted at the same frequency in a single communication channel simultaneously.As we all know, photons carry two different kinds of angular momentums, namely spin angular momentum (SAM) and OAM. [11] The SAM represents the polarization state of light, and the OAM is related to the spatial distribution of light. [1,12] Although mode conversion, [13] holograms, [14] spiral phase plates, [15] and spiral zone plates [16][17][18] can be used to generate vortex beam, they usually do not involve the interaction between SAM and OAM. [19] Different from the above, the geometric phase elements can establish a connection between SAM and OAM, but only two conjugate vortex states can be output. Devlin presented a method realizing arbitrary spin-to-OAM conversion, overcoming this limitation mentioned above. [20] In addition, when the paraxial beam is tightly focused, a strong longitudinal component will be generated in the focal area. [21] It is demonstrated that, in a highly focused system, a circularly polarized beam partly transfers its incident SAM to OAM and a helical phase in the longitudinal component of the electric field can be generated. [22] Due to their potential breakthroughs in optical manipulation, metasurfaces have attracted widespread attention in the scientific community. [23,24] Metasurfaces have been widely used in many applications, such as lenses, [25,26] spin Hall effect, [27] holograms, [28] and vortex generators. [29][30][31][32][33] In order to further Vortex beams, carrying orbital angular momentum (OAM), have plenty of applications ranging from particle manipulation to high-capacity data transmissions. In particular, the superpositions of OAM patterns are significant in classical physics and quantum science. The flexible control of spin angular momentum (SAM) to OAM can provide more freedom for the design of multifunctional devices. Here, a kind of dielectric metasurface is proposed that generates polarization-controllable superpositions of OAM patterns in the terahertz (THz) band, which is achieved by the interleaving of anisotropic and isotropic meta-atoms. The conversions of arbitrary S...

Self-powered and flexible ultrabroadband photodetectors (PDs) are desirable in a wide range of applications. The current PDs based on the photothermoelectric (PTE) effect have realized broadband photodetection. However, most of them express low photoresponse and lack of flexibility. In this work, high-performance, self-powered, and flexible PTE PDs based on laser-scribed reduced graphene oxide ( LSG ) / CsPbBr 3 are developed. The comparison experiment with LSG PD and fundamental electric properties show that the LSG / CsPbBr 3 device exhibits enhanced ultrabroadband photodetection performance covering ultraviolet to terahertz range with high photoresponsivity of 100 mA/W for 405 nm and 10 mA/W for 118 μm at zero bias voltage, respectively. A response time of 18 ms and flexible experiment are also acquired at room temperature. Moreover, the PTE effect is fully discussed in the LSG / CsPbBr 3 device. This work demonstrates that LSG / CsPbBr 3 is a promising candidate for the construction of high-performance, flexible, and self-powered ultrabroadband PDs at room temperature.

Photoerasable memories based on the organic field-effect transistor (OFET) have aroused great interest due to the advantages and potential applications, such as the erasure of confidential information. However, the complex manufacturing process of OFET memories is not conducive to large-scale production and market applications in the future. In this paper, the photoerasable memories are prepared by a simple solution process to disperse [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) in poly­(methyl methacrylate) (PMMA) thin films as a hybrid floating gate layer. The OFET memory devices present fast electrical programmable and photoerasable characteristics on the basis of matching energy band structure. With an optimal blending ratio of PCBM/PMMA, the memories present a long data retention time of 12 000 s during retention tests and a stable on/off drain-source current (I DS) switching behavior over 800 cycles during repeated erasing–reading–programming–reading (ERPR) cycling tests. A 2-bit storage capability is also obtained in the memories by trapping different numbers of holes. These characteristics of easy-to-manufacture and photoerasable memories are expected to open up new areas in the field of information storage.