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In this work, we integrated a periodic seed layer and oblique deposition method to fabricate a stochastically-distributed oblique-flat-sheet metamaterial perfect absorber (MPA). Such design could increase its absorption bandwidth and tolerance to high angle-incidence due to the fact that various oblique flat sheets offer different resonance conditions while even a single oblique flat sheet could provide different optical paths for resonance. On the other hand, a seed layer could reduce uncertainty regarding to direct oblique deposition and provide abilities to manipulate the bandwidth of the MPA. We also setup a simulation model in the aids of Visual Basic Application and examined the absorption behavior of the MPA under TM and TE oblique incidence that could achieve high absorbance under 80° and 60° incidence, respectively. Finally, in measurement, the fabricated sample owns 65% absorbance within 80–250 THz and over 90% absorbance within 250–320 THz at x-polarization normal incidence; as for the y-polarization normal incidence, we could achieve overall 70% absorbance within 80–300 THz. The measured results reveal similar tendency compared to the simulated ones.

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Narrow-band photodetectors based on halide perovskite have recently attracted significant attention due to their exceptional narrow-band detection performance and tunable absorption peaks covering a wide optical range. In this work, we report mixed-halide CH3NH3PbClxBr3-x single crystal-based photodetectors have been fabricated, where the Cl/Br ratios were varied (3:0, 10:1, 5:1, 1:1, 1:7, 1:14 and 0:3). Three different structures of devices were constructed by changing the connection of electrodes and the direction of light illumination. Both the vertical and parallel structure devices with bottom illumination exhibited ultranarrow spectral responses, with a full-width at half-maximum less than 16 nm. The observed performance can be ascribed to the unique carrier generation and extraction mechanisms within the single crystal under short and long wavelength of illumination. These findings offer valuable insights into the development of narrow-band photodetectors that do not necessitate the use of filters and hold tremendous potential for a diverse array of applications.

Due to its strong optical absorption in the near infrared (NIR) region, lead phthalocyanine (PbPc) is frequently used as the photoactive material in NIR sensitive organic phototransistors (OPTs). Limited by the low charge carrier mobility of NIR sensitive organic semiconductors, the active part of NIR OPTs adopts generally multilayer or multicomponent structure consisting of electron donor, electron acceptor and charge transporting molecules. Here, we investigate the effect of acceptor locations in the active structure on the performances of NIR phototransistors with PbPc as the photoactive electron donor. The performances of organic phototransistors with C60 layer lying on the top of PbPc [Si/SiO2/pentacene/PbPc/C60/Au (source and drain electrode, S&D)],above PbPc and Au source and drain electrode [Si/SiO2/pentacene/PbPc /Au (S&D) /C60)], and in the form of bulk-heterojunction with PbPc [Si/SiO2/pentacene/PbPc:C60 /Au(S&D)] were comparatively studied. The results show that the device with pentacene/PbPc:C60 exhibits the best performance among them. At an incident light intensity of 0.08 mW/cm2, a high photoresponsivity of 44.35 A/W, and specific detectivity of 1.08×1012 Jones are achieved.