Photoinduced Charge Transfer between CdSe Nanocrystal Quantum Dots and Ru−Polypyridine Complexes

Abstract

In this communication, we demonstrate a new approach to sensitization of Ru-polypyridine complexes by using semiconductor nanocrystal quantum dots (NQDs). When mixed in solution, the complexes functionalized by carboxylic groups adsorb onto the surface of the NQDs. Excitation of NQDs by 400 nm light leads to fast, 5 ps hole transfer from the photoexcited NQDs to the surface-adsorbed complexes. This result indicates that Ru complexes can be sensitized by CdSe NQDs, which opens interesting opportunities for designing new types of photocatalytic materials for solar energy conversion applications. These materials will take advantage of broad size-controlled absorption spectra and large extinction coefficients of NQDs as well as the unique property of NQDs to respond to absorption of a single photon by producing multiple electron-hole pairs.

Investigation on photoluminescence quenching of CdSe/ZnS quantum dots by organic charge transporting materials

“…However, the fluorescence lifetime of QDs cannot be changed by static quenching [16]. On the other hand, the energy difference between the highest occupied molecular orbital (HOMO) energy level of the OCTMs and the valence band of CdSe/ZnS QDs may lead to dynamic quenching [17]. When the QDs are excited, the holes in their top valence band can be transported to the HOMO energy levels of OCTMs, and then the separation of charge will happen in the interface of QDs and OCTMs.…”

Efficiency of Hole Transfer from Photoexcited Quantum Dots to Covalently Linked Molecular Species

“…(7) A growing body of spectroscopic work has examined charge transfer rates from QDs to molecular charge acceptors typically physisorbed onto the QD surface, exploring the parameter space in the Marcus equation. (8) Electron transfer studies (8)(9)(10)(11)(12)(13) outnumber hole studies, (14)(15)(16)(17)(18)(19) despite hole transfer being the limiting factor in the efficiencies of QD sensitized solar cells and in QD-based colloidal photocatalytic hydrogen evolving systems. (20,21) To establish a sound model for charge transfer from nanocrystals to molecular acceptors, we must address the features of this system that make the process more difficult to characterize than that of the pure molecular case.…”

Preparation of nanocrystals and nanocomposites of nanocrystal-conjugated polymer, and their photophysical properties in confined geometries

“…Thus, the number of from excited CdSe QD to P3HT may be expected in which the quenching of CdSe emission would be accompanied by a complementary growth of emission of P3HT at longer wavelength. 46 The P3HT/CdSe composites exhibited emission maximum at 670 nm, and the emission of CdSe QDs was completely suppressed, indicating the energy transfer from excited CdSe QDs to P3HT. The emission maximum of P3HT in the composite blue-shifted to 670 nm ( Figure 5-4b) as compared to the vinyl terminated P3HT in dry state in which λ em, P3HT = 730 nm ( Figure 5-2d).…”

“…A rectifying I-V curve was observed on a core-shell nanowire and a LED device was made accordingly. 46 Recently, the electron and hole mobility-lifetime were quantitatively measured by Lauhon et al by using scanning photocurrent microscopy with ohmic contacts. 47 By passivating the NC surface (e.g.,CdSe) with higher band gap materials, such as zinc sulfide (ZnS), the resulting CdSe/ZnS core/shell NCs possess a strong photoluminescence, 48 which is particularly important for use in biological applications 49,50 .…”