Solution‐Processed 3D RGO–MoS₂/Pyramid Si Heterojunction for Ultrahigh Detectivity and Ultra‐Broadband Photodetection

Abstract

Molybdenum disulfide (MoS ), a typical 2D metal dichalcogenide (2DMD), has exhibited tremendous potential in optoelectronic device applications, especially in photodetection. However, due to the weak light absorption of planar mono-/multilayers, limited cutoff wavelength edge, and lack of high-quality junctions, most reported MoS -based photodetectors show undesirable performance. Here, a structurized 3D heterojunction of RGO-MoS /pyramid Si is demonstrated via a simple solution-processing method. Owing to the improved light absorption by the pyramid structure, the narrowed bandgap of the MoS by the imperfect crystallinity, and the enhanced charge separation/transportation by the inserted reduced graphene oxide (RGO), the assembled photodetector exhibits excellent performance in terms of a large responsivity of 21.8 A W , extremely high detectivity up to 3.8 × 10 Jones (Jones = cm Hz W ) and ultrabroad spectrum response ranging from 350 nm (ultraviolet) to 4.3 µm (midwave infrared). These device parameters represent the best results for MoS -based self-driven photodetectors, and the detectivity value sets a new record for the 2DMD-based photodetectors reported thus far. Prospectively, the design of novel 3D heterojunction can be extended to other 2DMDs, opening up the opportunities for a host of high-performance optoelectronic devices.

Solution‐Processed Flexible Broadband Photodetectors with Solution‐Processed Transparent Polymeric Electrode

“…R and D * values at λ of 1300 and 2400 nm are compatible with those observed from 2D metal dichalcogenide based PDs. [ 5d,35 ] All these results certainly demonstrate that flexible solution‐processed broadband PDs with a vertical device structure exhibit high R and D * , indicating flexible solution‐processed broadband PDs have great potential applications. [ 36 ]…”

Light Confinement Effect Induced Highly Sensitive, Self‐Driven Near‐Infrared Photodetector and Image Sensor Based on Multilayer PdSe2/Pyramid Si Heterojunction

“…The detailed device fabrication process is shown in Figure S1 (Supporting Information). Briefly, the pyramid Si was first prepared by alkaline etching of n‐type lightly doped silicon wafer . Afterward, a layer of 10 nm metal palladium was evaporated onto pyramid Si through electron beam evaporation, followed by a simple selenization process of Pd.…”

Si/CuIn0.7Ga0.3Se2 Core–Shell Heterojunction for Sensitive and Self‐Driven UV–vis–NIR Broadband Photodetector

“…Responsivity ( R ), specific detectivity ( D* ), and response speed are key parameters to estimate the performance for a photodetector. Responsivity ( R ) indicates how the efficiency of a detector responds to optical signals and is defined as the ratio of the generated photocurrent in response to incident power, which is calculated according to the following equationwhere I p is the photocurrent, I d is the dark current, P is the light power intensity, and S is the active area (35 mm 2 for the as‐fabricated device). As shown in Figure a, the responsivity increases as the wavelength increases from 300 to 920 nm, and the peak value is attained at 920 nm, which is about 0.33 A W −1 at zero bias.…”

“…Even in the spectral range from 920 to 1100 nm, the responsivity exceeds 0.05 A W −1 . On the other hand, specific detectivity represents the capability of a photodetector to detect weak optical signals, which can be calculated from the following equation…”