One‐Step Self‐Assembly Fabrication of High Quality Ni_xMg_1‐xO Bowl‐Shaped Array Film and Its Enhanced Photocurrent by Mg,²⁺ Doping

Abstract

wileyonlinelibrary.combath deposition, [ 7 ] and electrochemical deposition [ 8 ] can be used to fabricate NiO and metal ions doped NiO fi lms, they usually involve either expensive equipments or complex fabrication procedures. [ 9 ] Recently, the bottom-up self-assembly has attracted considerable interest as a potential alternative to conventional top-down processes for the scalable, low-cost syntheses of nanoporous solid structures. [ 10 ] Monolayer, bilayer, or multilayer colloidal fi lm-based nanodevices have been reported by the oil-water interfacial self-assemble strategy. [ 11,12 ] Moreover, this method can be further extended for fabrication of high performance porous nanofi lm-based optoelectronic devices due to large surface-to-volume ratio and effi cient light harvest. [ 13 ] Nevertheless, the whole process seems to be complicated, including the self-assembly and drying of polymer colloidal spheres, the infi ltration of metal oxide precursors, the calcination and so on. Accordingly, a more facile method for fabrication of well-ordered pore nanofi lms for optoelectronic nanodevices is highly desired.In this study, we present the fi rst Ni x Mg 1 -x O bowl-shaped array fi lm by one-step self-assembly of monodisperse polystyrene (PS) colloid spheres and metal oxide precursors at oilwater interface and further construct the array fi lm-based optoelectronic device. Our approach at least has several prominent features: i) Unlike previous fabrication procedures, the crystal nuclei of the metal oxide precursors can directly self-assemble on the bottom surfaces of the organizing PS spheres to form a bowl-shaped nanofi lm. This greatly decreases the steps of fabrication. ii) Through this simple process, it is easy to realize the doping of other metal ions, which may tune the optoelectronic properties of the semiconducting fi lm-based nanodevices. iii) Compared with undoped NiO fi lms, doping of Mg 2+ significantly enhances the current and spectrum responsivity of NiO fi lm-based nanodevice. Results and Discussion Fabrication and Structure of Nix Mg 1 -x O Bowl-Shaped Array Films Scheme 1 briefl y describes the fabrication procedures of bowlshaped Ni x Mg 1 -x O nanofi lm and its corresponding optoelectronic device. Pure Ni(NO 3 ) 2 ·6H 2 O, or the mixture of Mg(NO 3 ) 2 ·6H 2 O and Ni(NO 3 ) 2 ·6H 2 O (mole ratios of Mg/(Mg+Ni): 0.05, 0.1, 0.2, A series of high quality Ni x Mg 1 -x O bowl-shaped array fi lms are successfully prepared by a simple one-step assembly of polystyrene colloidal spheres and metal oxide precursors at oil-water interface, and further used to fabricate nanodevices. The doping of Mg 2+ can greatly enhance the current and spectrum responsivity of NiO fi lm-based nanodevice. The maximum R λ value of these bowl-shaped Ni x Mg 1 -x O fi lm-based devices measured in the study shows 4-5 orders of enhancement than the previously reported Ni x Mg 1 -x O fi lm at equal doping.

High‐Performance Photodetectors Based on Organometal Halide Perovskite Nanonets

“…The unique perovskite nanonet holds promise for efficient photodetection because of three key advantageous features. First, the perforated‐bowl‐like structure has strong light scattering ability, thereby considerably enhancing light harvesting . Second, the nanonet with thin walls offers direct carrier transport pathways, favoring the diffusion and collection of photogenerated charges.…”

“…Recently, 2D inverse‐opal perovskite photonic films with vivid colors were successfully fabricated and their applications in colorful perovskite solar cells were explored . Notably, the fabrication of the photodetectors based on 2D‐ordered SnO 2 nanonets and Ni x MgO nanobowl arrays has been achieved using nanosphere lithography. The nanonets and nanobowl arrays have large surface‐to‐volume ratios, which are favorable for charge separation at the interface, and the optical absorption was significantly enhanced due to the bowl‐like structure.…”

Unpacking the toolbox of two-dimensional nanostructures derived from nanosphere templates

“…Notably, similar porous geometry was previously adopted by Wu's group to nanostructure SnO2 and Mg 2+ doped NiO achieved via a one-step oil-water interface self-assembly process. 281,282 Both photodetector devices based on these two nanostructures exhibited impressively high enhancements of photocurrent. The enhanced light harvesting ability was also found in the photodetectors based on hollow spherical nanoshell arrays of MoSe2 and MoS2 fabricated via 2D colloidal crystal templating and chemical vapor deposition.…”

Fabrication and Photo-Detecting Performance of 2D ZnO Inverse Opal Films

“…Monodisperse PS template microspheres with average diameter of 300 nm were synthesized by emulsion polymerization similar to our previous work [22], as follows: St (10.0 g), PVP (1.0 g), and H 2 O (90.0 g) were charged into a 250 mL four-neck flask with a temperature controller, a mechanical stirrer, a N 2 inlet, and a Graham condenser. The reaction system was stirred at a rate of 200 rpm and deoxygenated by N 2 at room temperature for 30 min.…”

“…Very recently, we fabricated Ni x Mg 1-x O nanobowl array photo-detecting devices via the oil-water interfacial assembly of polystyrene (PS) colloids and metal oxide precursors, followed by calcination [22]. However, for the device constructed by Ni x Mg 1-x O, the photocurrent and selectivity still need to be improved.…”