About this Research Topic
Silicon is a widespread semiconductor, owing to its diffusion to its earth abundance, availability of fabrication methods, and its photovoltaic properties. The formation of hybrid silicon/organic interfaces through controlled growth of self-assembled monolayers (SAMs) of (in)organic molecules represents a smart way to tune the functionality of this semiconductor toward a speciﬁc device.
In recent decades, major advances have been pursued in the functionalization of silicon surfaces with organic, inorganic and organometallic molecules, as well as hierarchic supramolecular structures, metal nanoparticles, and carbon nanostructures. The impact has been important for several areas of chemistry, electrochemistry, electronics and biomedicine, with an expanding wealth of applications in memory devices, optical energy conversion, sensors, molecular electronics and biologically active interfaces. The synergy between the properties of the inorganic surface and the chemically bound molecular layers is able to afford an almost unlimited range of functionalities, which allows building molecular-scale devices on silicon with tuneable chemical, electronic and photoelectronic characteristics.
To this aim, one of the major hurdles is represented by the functionalization of silicon surfaces without significant levels of SiOx, which can adversely affect the electronic properties of the silicon electrode. In fact, the formation of a direct and robust covalent bond between Si atoms and the molecular moiety without an oxide inter-layer is a crucial condition to ensure a defect-free interface, with direct electronic coupling between the surface and the organic functionality. Direct attachment of organic layers to oxide-free Si surfaces can relatively easily be achieved by pre-treating the oxidized substrates in fluoride solutions (e.g. aqueous HF) leading to H-termination of the Si surface. The following functionalization process involves the formation of Si–X bonds at the interface by means of several wet chemical methods, such as metal complex catalyzed reactions, radical-induced hydrosilylation of unsaturated organics, “click-chemistry” based pathways, electrochemical grafting routes, and reactions with Grignard or lithium reagents.
The aim of the current Research Topic is to cover promising, recent, and novel research trends in functionalization of oxide-free silicon surfaces, both crystalline and porous. The Topic Editors welcome submissions of Original Research, Review, Mini Review and Perspective articles that address, but are not limited to;
• Properties of Si surfaces modified with organic molecules and their applications in electrochemical devices
• Advances in synthetic strategies for the formation of robust Si-molecule bonds
• Advances in the comprehension of Si-molecule covalent bond formation reaction mechanisms
• Advanced characterization of electron transfer properties at Si/molecule interfaces
• New trends in the application of Si/SAM interfaces in host-guest chemistry and molecular recognition
• Hierarchical supramolecular structures on Si, functionalization with metal nanoparticles or carbon nanostructures
Keywords: Silicon, surface functionalization, self-assembled monolayers, molecular electronics, Si-molecule bond
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