InP Quantum Dot-Organosilicon Nanocomposites

Abstract

InP quantum dot (QD)-organosilicon nanocomposites were synthesized and their photoluminescence quenching was mainly investigated because of their applicability to white LEDs (light emitting diodes). The as-synthesized InP QDs are capped with myristic acid (MA), which are incompatible with typical silicone encapsulants. We have introduced a new ligand, 3-aminopropyldimethylsilane (APDMS), which enables embedding the QDs into vinyl-functionalized silicones through direct chemical bonding. The exchange of ligand from MA to APDMS does not significantly affect the UV absorbance of the InP QDs, but quenches the PL to about 10% of its original value with the relative increase in surface related emission intensities, which is explained by stronger coordination of the APDMS ligands to the surface indium atoms. InP QD-organosilicon nanocomposites were synthesized by connecting the QDs using a short cross-linker such as 1,4-divinyltetramethylsilylethane (DVMSE) by the hydrosilylation reaction. The formation and changes in the optical properties of the InP QD-organosilicon nanocomposite were monitored by ultraviolet visible (UV-vis) absorbance and steady state photoluminescence (PL) spectroscopies. As the hydrosilylation reaction proceeds, the QD-organosilicon nanocomposite is formed and grows in size, causing an increase in the UV-vis absorbance due to the scattering effect. At the same time, the PL spectrum is red-shifted and, very interestingly, the PL is quenched gradually. Three PL quenching mechanisms are regarded as strong candidates for the PL quenching of the QD nanocomposites, namely the scattering effect, Förster resonance energy transfer (FRET) and cross-linker tension preventing the QD's surface relaxation.

Small-Size Effects on Electron Transfer in P3HT/InP Quantum Dots

“…As shown in Figure b, the In 3d XPS spectrum exhibits two contributions, 3d 5/2 and 3d 3/2 , respectively located at 447 and 454 eV, which are subject to a rather small shift (less than 1 cm –1 ) due to formation of In–N­(pyridine) bonds upon ligand exchange. This suggests that N atoms bind much stronger to In rather than to P atoms, in agreement with previous findings by Dung et al Nevertheless, in InP­(4.5 nm) the red shift of the 3d 5/2 and 3d 3/2 peaks is larger than in InP­(2.5 nm), most likely due to the high binding efficient of pyridine on the surface. The P 2p spectrum shown in Figure S1 indicates the presence of two chemical environments for the P atoms: the predominant peak, with binding energy below 130 eV, is characteristic of InP; the other peak, located at higher binding energies (133.2–134.1 eV), can be attributed to the phosphorus in an oxidized environment (InPO x ) .…”

Novel synthesis of covalently linked silicon quantum dot–polystyrene hybrid materials: Silicon quantum dot–polystyrene polymers of tunable refractive index

“…This peak-broadening may occur due to surface broadening effect of organics on the Si QD surface as explained in Fig. 2 [37,38]. The increase in the extent of peak-broadening strongly supports increase in the number of polystyrene on the Si QD as the content of Si QD increases from the Si QDePS-A, to QDePS-B, to QDePS-C.…”

“…2). The peak-broadening possibly occurred because of attachment of the molecule (DVB) to the QD surface, known as the surface broadening effect [37,38], These spectra indicate that the Si QD is capped by the DVB molecule. By capping the DVB on the Si QD via Pt-catalyzed hydrosilylation, one vinyl group in the DVB molecule undergoes the conversion to an ethyl group, of which protons can be newly found at around 1.2 ppm (i and j) [31,39].…”

Tuning the Emission Color of Hydrothermally Synthesized Carbon Quantum Dots by Precursor Engineering

“…When compared with mature nontoxic QDs, e.g. InP [3], Si [4][5][6][7] or visible luminescence ZnO particle [8], CQDs have advantages of large chemical abundance and cost-effective synthesis but the information relating to chemical structures and photoluminescence origin of CQDs is lag behind. Among a vast number of reported CQDs, CQDs derived from CA and EDA are probably the CQDs that have been described in most detail [9][10][11].…”