Covalently bonded organic monolayers play important roles in defining the solution processability, ambient stability, and electronic properties of two-dimensional (2D) materials such as Ge nanosheets (GeNSs); they also hold promise of providing avenues for the fabrication of future generation electronic and optical devices. Functionalization of GeNS normally involves surface moieties linked through covalent Ge−C bonds. In the present contribution we extend the scope of surface linkages to include Si−Ge bonding and present the first demonstration of heteronuclear dehydrocoupling of organosilanes to hydride-terminated GeNSs obtained from the deintercalation and exfoliation of CaGe2. We further exploit this new surface reactivity and demonstrated the preparation of directly bonded silicon quantum dot-Ge nanosheet hybrids.

Herein, silicon quantum dot light‐emitting diodes (SiQD LEDs) are investigated to explore the interplay between their electroluminescence (EL) blue shift and the SiQD ligand length on the SiQD surface. The ligand is essential for LED fabrication to ensure colloidal stability, but it also hinders efficient charge transport inside the LED. Consequently, the SiQDs are functionalized via organolithium reagents with hexyl, octyl, and dodecyl to obtain a low‐SiQD surface coverage and therefore improved charge transport. With increasing ligand length, the potential barrier between the SiQDs increases, which is ideal for charge carrier confinement, but a trade‐off with the charge transport has to be found. A sweet spot for LED performance is found for octyl‐functionalized SiQDs with the highest irradiance (734 μW cm−2) and external quantum efficiency (1.48%), compared with shorter hexyl‐ and longer dodecyl‐capped SiQDs. The SiQDs exhibit a size distribution, whereas the bandgap energy of SiQDs is inversely proportional to the SiQD size. Therefore, large SiQDs with a short ligand are accessible at low voltages, whereas small SiQDs with long ligands require elevated voltages. This leads to a broadening and a blue shift of the EL spectrum and a ligand length‐controlled size‐selective SiQD activation.

Surface‐anisotropic nanoparticles represent a new class of materials that shows potential in a variety of applications, including self‐assembly, microelectronics, and biology. Here, the first synthesis of surface‐anisotropic silicon quantum dots (SiQDs), obtained through masking on 2D silicon nanosheets, is presented. SiQDs are deposited on the 2D substrate, thereby exposing only one side of the QDs, which is functionalized through well‐established hydrosilylation procedures. The UV‐sensitive masking substrate is removed through UV‐irradiation, which simultaneously initiates the hydrosilylation of a second substrate, thereby introducing a second functional group to the other side of the now free‐standing SiQDs. This renders surface‐anisotropic SiQDs that have two different functional groups on either side of the particle. This method can be used to introduce a variety of functional groups including hydrophilic and hydrophobic substrates, while the unique optoelectronic properties of the SiQDs remain unaffected. The anisotropic morphology of the QDs is confirmed through the aggregation behavior of amphiphilic Janus SiQDs at the interface of water and hexane. Additionally, anisotropic SiQDs are used to produce the first controlled (sub)monolayer of SiQDs on a gold wafer.

Diaryliodonium salts were found to initiate hydrosilylation reactions on the surface of silicon nanosheets as well as silicon nanocrystals of different sizes. A variety of different functional substrates can be used to stabilize the surface of the photoluminescent materials. Additionally, the combination of hydride terminated silicon nanomaterials with diaryliodonium salts was found to initiate cationic ring opening polymerization, demonstrating the potential of silicon based nanomaterials as coinitiators and enabling a mild, straightforward reaction method.

Silicene, the silicon analogue of graphene, represents a new class of two-dimensional (2D) materials, which shares some of the outstanding physical properties of graphene. Furthermore, it has the advantage of being compatible with the current Si-based technology. However, this 2D material is not stable and is quite prone to oxidation. The hydride-terminated silicene, called silicane, is a more stable form of 2D silicon, if functionalized via, for example, the hydrosilylation reaction. In this work, the third-order nonlinear optical (NLO) properties of two functionalized silicanes, namely hydride-terminated silicon nanosheets (SiNS-H) and 1-dodecene-functionalized silicon nanosheets (SiNS-dodecene), are accessed and compared to those of single-layer graphene, under 35 ps, 532 and 1064 nm excitation. The present results show that the functionalized silicanes exhibit comparable and even higher NLO response than that of single-layer graphene, making them strong competitors of graphene and very interesting candidates for future photonic and optoelectronic applications.