Triethyl-Borates as Surfactants to Stabilize Semiconductor Nanoplatelets in Polar Solvents and to Tune Their Optical Properties

Abstract

Stabilizing nanocrystals (NCs) with high fluorescence quantum efficiency in suitable solvents and tuning of their optical properties precisely are critical for designing and assembling optoelectrical devices. Here, we demonstrated that by replacing the original X-type ligand (R-COO-) with triethylborate (TEB), zinc-blend structure nanoplatelets (Zb-NPLs) turn from hydrophobic to hydrophilic and are quite stable in polar solvents. More importantly, a large shift of 253 meV is observed for the TEB-passivated NPLs, which can be attributed to the strain of the crystal lattice and the electron or hole delocalizing into the ligand shell. It is worth noting that unlike conventional inorganic ligands, such as metal chalcogenide complexes or halides that quench fluorescence, TEB-treated NPLs maintain 100% of their original brightness in polar solvents with a slight increase in full width at half maximum (FWHM, 32 nm). Furthermore, we explored the possibility of employing TEB as surface ligands for NPLs with different thicknesses and compositions. We believe the discovery of new surface chemistry using borate-related ligands can greatly expand the potential application areas of NPLs.

Covalent inorganic complexes enabled zinc blende to wurtzite phase changes in CdSe nanoplatelets

“…44 We attributed the spectral shi to lattice stretching and an increase in the effective connement dimension due to the electronic coupling between the surface ligands and the NPLs. [48][49][50] This hypothesis was supported by the high-angle XRD measurements of the products at different incubation times (Fig. S7a †).…”

“…In particular, the (002) crystal plane of ZB CdSe NPLs was split into two diffraction peaks, including the lateral (yellow line) and thickness (green line) directions. 48,51 As the experiment progressed, there was a reduction of the diffraction angle along the vertical connement (indicated by the green line) from 42.8°to 40.6°, suggesting an extension of the lattice. 49 This also led to broadening of the diffraction peak.…”

Designing inorganically functionalized magic-size II–VI clusters and unraveling their surface states

“…[17][18][19] The treated NCs show higher electron mobility and improved electrochemical and catalytic performance. [20][21][22][23][24] However, the strategy is not applicable to MSCs because of their high sensitivity to the environment. 4,9,25 In addition, the lack of suitable techniques for the studies of MSC surface chemistry further hindered an in-depth understanding of their properties at the molecular level.…”