Fast Photothermoelectric Response in CVD‐Grown PdSe₂ Photodetectors with In‐Plane Anisotropy

Abstract

PdSe2, a star photosensitive functional material, has been successfully used in photodetectors based on sensing mechanisms of photogating, photoconductive, and photovoltaic effects. Here, a photothermoelectric (PTE) effect is observed in photodetectors based on PdSe2 flakes grown by chemical vapor deposition. The unique photoresponse arises from an electron temperature gradient instead of electron–hole separation. Direct evidence of the PTE effect is confirmed by a nonlocal photoresponse under zero bias. Moreover, the PdSe2 photodetector shows high performance in terms of ultrafast response speed (4 µs), high air‐stability, broadband spectrum photodetection, reasonable responsivity, and anisotropic optical response. This study paves a new way for developing high‐performance photodetectors based on PdSe2 layered materials.

Quantitative Determination of Contradictory Bandgap Values of Bulk PdSe2 from Electrical Transport Properties

“…The Pd 3d 3/2 and 3d 5/2 peaks located at 341.7 and 336.5 eV and the Se 3d 3/2 and 3d 5/2 peaks located at 55.1 and 54.3 eV for as-exfoliated PdSe 2 crystals are consistent with the characteristic binding energies of PdSe 2 crystals. [20,32,39] An unknown peak (*) is found at ≈51 eV. Since the bulk PdSe 2 was grown by the self-flux method and the remaining Se and other residues were not removed from PdSe 2 crystals before the transfer, this peak may be due to the residual element.…”

“…These results are consistent with that of previous studies. [20,32,49,50] The anisotropic intensity of the g 1 A peak in the ( ) z xx z configuration is shown with the crystal axes in the crystal image in Figure 1e. This anisotropic behavior makes it possible to determine the crystal orientation.…”

Highly Efficient, Ultrabroad PdSe2 Phototransistors from Visible to Terahertz Driven by Mutiphysical Mechanism

“…Based on the inherent low lattice thermal conductivity, lower-symmetry materials have been widely used in thermoelectric applications. − Considering the high carrier mobility and large Seebeck coefficient (>200 μV·K –1 ) of PdSe 2 , , the efficient detection for THz waves could be realized by the photothermoelectric (PTE) effect. Previous reports have demonstrated that it can respond from the visible to the mid-infrared (4.05 μm) and expand to the long-wavelength infrared (10.6 μm) via heterogeneous integration with other 2D materials. ,− Notably, these PDs involve solely the usage of bandgap-matching with incident photons limiting the application of broad-spectrum and self-powered devices. For instance, the photoconductive mechanism of single-material PDs driven by external voltage introduce a bandgap-related response with a non-negligible noise signal and energy consumption …”

Binary pentagonal auxetic materials for photocatalysis and energy storage with outstanding performances

“…18–21 Recently, some pentagonal materials such as Penta-PdSe 2 , Penta-PdPSe, and Penta-NiN 2 have been synthesized experimentally, ensuring the experimental synthesis possibility and research value of these pentagonal materials. 22–24…”