Si/CuIn_0.7Ga_0.3Se₂ Core–Shell Heterojunction for Sensitive and Self‐Driven UV–vis–NIR Broadband Photodetector

Abstract

to the high conductivity and transparency of graphene. [8] Nevertheless, high dark current arising from the gapless of graphene is detrimental to the responsivity and detectivity of this hybrid system. Si/ metal sulfide system suffers from severe recombination due to a large number of trap defects in low-crystalline sulfides that are grown by the hydrothermal or solvothermal processes. [9] Therefore, it is essential to develop promising semiconductors to couple with Si to enhance the photoelectric performance.In addition, when constructing Si NW-based heterojunction for high-performance, broadband, and self-powered photodetectors, the following factors should be considered: i) the deposition approach. The growth strategy for the outer semiconductor should be compatible with Si NW, and the process will not damage the structure and conductivity of Si. ii) The device configuration. Low-dimensional architecture can effectively suppress the dark current, and promote the charge carrier separation and transportation. iii) The physical parameters of the semiconductor itself. The bandgap of the semiconductor should be as small as Si to ensure wide absorption range, and their band alignment must be suitable to guarantee efficient charge separation and transfer across interfaces. CuIn x Ga 1−x Se 2 (CIGS) in its chalcopyrite phase has attracted considerable interest as a promising p-type light absorber, owing to its tunable band energy (1.0-1.7 eV), large optical absorption coefficient (≈10 5 cm −1 ), outstanding thermal, environmental and electrical stabilities. [10][11][12] In terms of application, CIGS thin films have been used in thin-film solar cells, solar modules, and photoelectrochemical photocathodes. [13][14][15] The above-stated excellent features also make CIGS great potential application in broadband photodetection. For example, Pan and co-workers designed an indium tin oxide (ITO)/ZnO/CdS/ CIGS/Mo heterojunction on the polyimide substrate to form a flexible CIGS heterojunction photodetector. [11] Wang and coworkers demonstrated a visible-NIR optical position sensitive detectors based on Mo/CIGS/CdS/ZnO/ITO/glass structure. [16] Although several investigations on the photodetector application of CIGS have been carried out, and impressive performances are demonstrated, the devices reported are usually built of CIGS thin-film based multilayer heterojunction. The bulk film and the multiple interfaces possibly bring about severe charge carrier recombination, limiting the photoelectric performance. In addition, a CdS layer is always inserted into the Designing Si nanowire-based heterostructures provides a promising path to construct self-driven and broadband photodetectors, which are the key components for optoelectronic systems. Herein, the first fabrication of a p-CuIn 0.7 Ga 0.3 Se 2 nanoparticles/n-Si nanowire array core-shell structure through a simple two-stage process-spin coating and selenization treatment-and its integration into a self-driven photodetector are reported. The heterojunction photodetector is ...

Solution-Processed Black-Si/Cu2ZnSnS4 Nanocrystal Heterojunctions for Self-Powered Broadband Photodetectors and Photovoltaic Devices

“…The device exhibits a broadband responsivity ranging from 300 to 1100 nm. The maximum responsivity is found to be ∼414 mA W −1 at ∼800 nm, which is higher than those of the recently reported Si/ CIGS core−shell heterojunction, 24 graphene/planar-Si Schottky diode 41 and far larger than Si/perovskite core−shell heterojunctions. 23 Apparently, the observed excellent spectral response without any exterior power supply confirms that the built-in electric field efficiently separates the photogenerated carriers in the space charge region.…”

“…Thus, it is important to design a novel semiconductor to integrate with Si to enrich the photoresponse characteristics. For instance, Chen et al 24 reported the fabrication of a Si/CuIn x Ga 1−x Se 2 (CIGS) core/shell heterojunction and demonstrated its admirable photodetection characteristics. However, the fabricated device is limited to photodetection applications only.…”

Sulfate-Functionalized Core–Shell ZnO/CdS/Ag2S Nanorod Arrays with Dual-Charge-Transfer Channels for Enhanced Photoelectrochemical Performance

“…As shown in Figure 6d, after the contact, the Fermi level equilibrium could be achieved in the interface due to the migration of electrons, and the band edges of each component near the contact interface bend, theoretically capable of forming a gradient energy band configuration. 42,43 Such an energy band configuration could accelerate the photogenerated hole transport from the ZnO core to CdS and Ag 2 S, thus increasing the reaction chance between the photogenerated holes and electrolyte, and decreasing the recombination of photogenerated charge carriers. 7f).…”

Self‐assembled core‐shell structured organic nanofibers fabricated by single‐nozzle electrospinning for highly sensitive ammonia sensors

“…Several remarkable strategies have been employed to enhance the sensing performance of OSC‐based chemical sensors such as designing novel molecular structures, adding specific receptors on OSCs film, and modifying the film thicknesses . In addition, one‐dimensional (1D) materials with unique nanostructure (nanofiber, nanobelt, and nanotube) are suitable for low‐concentration detection, which offer high sensitivity and fast response time for chemical sensors because of the large surface‐to‐volume ratios in 1D materials.…”

“…31 Several remarkable strategies have been employed to enhance the sensing performance of OSC-based chemical sensors such as designing novel molecular structures, adding specific receptors on OSCs film, and modifying the film thicknesses. [32][33][34][35][36][37] In addition, one-dimensional (1D) materials with unique nanostructure (nanofiber, nanobelt, and nanotube) are suitable for low-concentration detection, which offer high sensitivity and fast response time for chemical sensors because of the large surface-to-volume ratios in 1D materials. Numerous synthetic methods have been developed to prepare 1D structured nanofibers of which electrospinning is a simple, fast, and cost-effective approach to fabricate nanowire materials by electrostatic stretching.…”