Palladium diselenide (PdSe 2 ), a thus far scarcely studied group-10 transition metal dichalcogenide has exhibited promising potential in future optoelectronic and electronic devices due to unique structures and electrical properties. Here, the controllable synthesis of wafer-scale and homogeneous 2D PdSe 2 film is reported by a simple selenization approach. By choosing different thickness of precursor Pd layer, 2D PdSe 2 with thickness of 1.2-20 nm can be readily synthesized. Interestingly, with the increase in thickness, obvious redshift in wavenumber is revealed by Raman spectroscopy. Moreover, in accordance with density functional theory (DFT) calculation, optical absorption and ultraviolet photoemission spectroscopy (UPS) analyses confirm that the PdSe 2 exhibits an evolution from a semiconductor (monolayer) to semimetal (bulk). Further combination of the PdSe 2 layer with Si leads to a highly sensitive, fast, and broadband photodetector with a high responsivity (300.2 mA W −1 ) and specific detectivity (≈10 13 Jones). By decorating the device with black phosphorus quantum dots, the device performance can be further optimized. These results suggest the asselenized PdSe 2 is a promising material for optoelectronic application.

Group-10 layered transitional metal dichalcogenides including PtS2, PtSe2 and PtTe2 are excellent potential candidates for optoelectronic devices due to their unique properties such as high carrier mobility, tunable bandgap, stability and flexibility. Large-area platinum diselenide (PtSe2) with semiconducting characteristics is far scarcely investigated. Here, we report on the development of a high performance photodetector based on vertically aligned PtSe2-GaAs heterojunction which exhibited a broadband sensitivity from deep ultraviolet (DUV) to near infrared (NIR) light, with peak sensitivity from 650 to 810 nm. The Ilight/Idark ratio and responsivity of photodetector were 3×10 4 and 262 mA W −1 measured at 808 nm under zero bias voltage. The response speed of τr/τf were 5.5/6.5 μs, which represented the best result achieved for Group-10 TMDs based optoelectronic device thus far. According to first-principle density functional theory, the broad photoresponse ranging from visible to near infrared region is associated with the semiconducting characteristics of PtSe2 which has interstitial Se atoms within the PtSe2 layers. It was also revealed that the PtSe2/GaAs photodetector did not exhibit performance degradation after 6 weeks in air. The generality of the above good results suggests that the vertically aligned PtSe2 is an ideal material for high-performance optoelectronic systems in the future.

In this study, MAPbBr3 single crystal (MSC) p‐n perovskite homojunction photodiode and n‐p‐n phototriode are successfully fabricated through controlled incorporation of Bi3+ ions in solution. Optoelectronic analysis reveals that the photodiode shows typical photovoltaic behavior and the best photovoltaic performance can be achieved when the n‐type MSC is grown in 0.3% Bi3+ feed solution. The as‐assembled p‐n MSC photovoltaic detector displays obvious sensitivity to 520 nm illumination, with a high responsivity of up to 0.62 A W‐1 and a specific detectivity of 2.16 × 1012 Jones, which surpass many those of MSC photodetectors previously reported. Further performance optimization can be realized by constructing an n‐p‐n phototriode using the same growth method. The photocurrent magnification rate of the as‐fabricated n‐p‐n phototriode can reach a maximum value of 2.9 × 103. Meanwhile, a higher responsivity of 14.47 A W‐1, specific detectivity of 4.67 × 1013 Jones, and an external quantum efficiency of up to 3.46 × 103 are achieved under an emitter–collector bias of 8 V. These results confirm that the present p‐n and n‐p‐n MSC homojunctions are promising device configurations, which may find potential application in future optoelectronic devices and systems.

The split feasibility problem is to find an element in the intersection of a closed set C and the linear preimage of another closed set D, assuming the projections onto C and D are easy to compute. This class of problems arises naturally in many contemporary applications such as compressed sensing. While the sets C and D are typically assumed to be convex in the literature, in this paper, we allow both sets to be possibly nonconvex. We observe that, in this setting, the split feasibility problem can be formulated as an optimization problem with a difference-of-convex objective so that standard majorization-minimization type algorithms can be applied. Here we focus on the nonmonotone proximal gradient algorithm with majorization studied in [21, Appendix A]. We show that, when this algorithm is applied to a split feasibility problem, the sequence generated clusters at a stationary point of the problem under mild assumptions. We also study local convergence property of the sequence under suitable assumptions on the closed sets involved. Finally, we perform numerical experiments to illustrate