A Sustainable Self‐Induced Solution Seeding Approach for Multipurpose BiFeO₃ Active Layers in Flexible Electronic Devices

Abstract

The direct integration of crystalline oxide layers into flexible electronic systems requires the development of relatively simple, low-temperature processing routes. Seeding represents a powerful strategy to reach this objective by the generation of preferential sites for the nucleation of crystalline phases with a reduced energy barrier. Here, a novel approach is reported where nanoseeds are generated in situ from a precursor solution using a solvent-engineering strategy (solvent-antisolvent). The controlled addition of an antisolvent (1,3-propanediol) to a solution of metal salts (Bi/Fe) dissolved in acetic acid results in the formation of nanocrystals (seeds) by supersaturation. The presence of such nanoseeds is also confirmed in the deposited layers, improving significantly the crystallinity of the respective BiFeO 3 thin films as complementary, deduced by piezoresponse force microscopy. Using this low-temperature strategy, crystalline films are directly grown on flexible polymeric substrates at only 350 °C showing a remanent polarization of 10.5 µC cm −2 and a clear photovoltaic effect (11.7 µW cm −2 ) of interest in computer memories and energy harvesters. The flexibility of the BiFeO 3 thin films may enlarge the number of applications of this multifunctional, lead-free material in next-generation digital and sustainable electronic devices based on a facile, low-cost fabrication method with reduced energy consumption.

In situphotogenerated hydroxyl radicals in the reaction atmosphere for the accelerated crystallization of solution-processed functional metal oxide thin films

“…For the flexible films, these treatments were made using special home-built sample holders. 41 To demonstrate the efficiency of the UV-irradiation, similar films were deposited from the same solutions and subjected to the same processes but without UV-irradiation, under the same atmospheres and in air (Fig. S3, ESI †).…”

“…are needed for achieving an adequate performance at low temperatures (see Table S1, ESI† that summarizes the properties of high- k dielectric films processed from solution at temperatures ≤400 °C). 1,9,14–42 Ferroelectric thin films provide besides a wide range of electrical properties (ferro-, pyro-, piezoelectricity) that make them excellent candidates for their use in multifunctional electronic devices of emerging technologies. Finally, this low-temperature solution deposition method assisted by hydroxyl radicals can be applicable to the fabrication of metal oxide thin films of different compositions with either an amorphous or crystalline structure.…”

Low-temperature sol–gel methods for the integration of crystalline metal oxide thin films in flexible electronics

“…The in-situ generation of seeds in the precursor solution is also possible and for that we have developed a novel self-induced solution seeding approach (Fig. 7), which has permitted the fabrication of BiFeO 3 perovskite films on flexible polyimide substrates [26]. This strategy makes use of the controlled addition of an antisolvent, 1,3-propanediol, to an acetic acid solution of Bi(III) and Fe(III) salts.…”

Design of super-elastic freestanding ferroelectric thin films guided by phase-field simulations

“…Although PI substrates have better mechanical ductility and flexibility, the temperature they can withstand (< 400 °C) cannot reach the crystallization temperature of ferroelectric oxides (> 600 °C). Bretos et al proposed a series of solution-based approaches to realize the low-temperature crystallization of ferroelectric thin films, such as BiFeO 3 and Pb(Zr,Ti)O 3 [85][86][87][88][89] . In addition to the aforementioned direct growth on flexible substrates, mechanical exfoliation along heterointerfaces after the deposition of ferroelectric thin films onto 2D layered materials has also been developed.…”