High-efficient SERS substrates containing dense hot spots were fabricated by assembling 3D Ag nanoflowers (AgNFs)@Au-FTO substrate by using citrate ions as the shape-guiding agent. The vertical growth of 3D AgNFs could be attributed to the synergistic effects of the concentration gradient layer of Ag + and the density gradient of the charge carrier. Combined with the simulation result of FDTD method, the enhanced SERS sensitivity and repeatability of AgNFs@Au-FTO could be attributed to the enlarged specific surface area, and the improved density of hot spots contributed by the overlap between the vertically stacked AgNSs with a high population of sharp edges.
Wang Jinxin,Jiang Guicheng,Huang Weicheng,Liu Danqing,Yang Bin,Cao Wenwu
Materials with an electrocaloric effect (ECE) have been extensively studied for their cooling applications. Most ECE films are oriented and are difficult to integrate into industrial production processes. Here, an ECE ( ΔS = 4.48 J K −1 kg −1 and ΔT = 6.4 °C at ΔE = 390 kV cm −1 ) is obtained in an unoriented PbZr 0.95 Ti 0.05 O 3 (PZT) film fabricated on an FTO substrate using an improved sol-gel method. To improve the ECE, Si-doped PZT films with 1–4 mol. % of Si are deposited. X-ray diffraction and X-ray photoelectron spectroscopy results confirm that Si was doped into the PZT lattice. The orthorhombic and tetragonal antiferroelectric phases coexist in the PZT/0.01 Si film. A large ECE ( ΔS = 5.89 J K −1 kg −1 and ΔT = 8.5 °C at ΔE = 390 kV cm −1 ) is acquired in the PZT/0.01 Si film, which was measured by an indirect method. This work demonstrates that ECE of unoriented PZT antiferroelectric films on FTO substrates can be improved by a certain amount of Si doping.
Jinxin Wang,Guicheng Jiang,Weicheng Huang,Danqing Liu,Bin Yang,Wenwu Cao
PbTiO 3 (PTO) and Cu-doped PbTiO 3 thin films were deposited on the fluorine doped tin oxide (FTO) by a sol-gel route. Detailed investigations were made on the effects of Cu doping on the crystal structure and ferroelectric properties of the thin films. With increasing Cu amount, the crystal structure of Cu-doped films gradually transits from tetragonal to pseudo-cubic phase. Worth mentioning, the Cu-doped can induce a superior giant remnant polarization of ∼55.7 μC/cm 2 and a relatively low coercive field of 304 kV/cm when the molar concentration of Cu in the sol is 0.02. The experimental results show that Cu-doped PbTiO 3 is very a promising candidate for ferroelectric random access memory (FERAMs) applications.
Cuicui Zhou,Shiqi Hong,Xinyu Chen,Quanfeng Li,Zongqi Chen,Songwang Yang
The electron transport layer (ETL) plays a critical role in efficient and stable perovskite solar cells (PSCs). The current effective method for the large-scale preparation of metal oxide ETLs is mainly based on expensive sputtering processes. Here, a screen-assisted self-spreading method is proposed as a novel approach to prepare uniformly thin and conformal TiO2 films on a rough fluorine-doped tin oxide (FTO) substrate as an ETL in planar PSCs. The TiO2 ETL deposited by this method exhibited good coverage and homogeneity on the rough FTO substrate, thereby minimizing interfacial recombination. The photovoltaic performance of the PSCs fabricated by this method is superior to that of the cells fabricated by spin coating, especially in terms of the fill factor. The performance enhancement can be attributed to the complete coverage of the FTO substrate by the conformal TiO2 film, confirming the effectiveness and reliability of the proposed method for the preparation of the TiO2 ETL. The advantages of this method lie in its scalability to prepare oxide films with a large area, eliminating the requirement of complex equipment, such as spinners, sputters, or physical vapor deposition equipment.
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