Nanocrystal-based Dyads for Solar to Electric Energy Conversion
Collaborators:    Prof. Ron Naaman,
                         Prof.  David N. Beratan,
Group Members:  Mingyan Wu ,Brian Bloom, Robin Sloan
Inorganic nanoparticle-polymer composites offer great promise in the creation of  bulk heterojunction solar cells. By manipulating the nanoparticle size, composition, and surface chemistry, one can control the nanoparticle’s energetics and tune the bandgaps in order to span the solar spectrum from visible to near-IR (see Figure 1).
Figure 1. UV-vis, photoluminescence image and photoluminescence spectra of CdTe nanoparticles(NPs) in water
We are exploring a systematic and modular approach to developing a new generation of solar energy conversion devices based on linked-nanoparticles, or dyads (see figure 2).
 Figure 2: NP dyad
The dyads will be created so that they migrate to the boundary between two phases of a conducting polymer blend in which one polymer phase functions as the cathode and the other functions as an anode in a photoelectric device. Upon light illumination, the dyads will convert absorbed photons into electrical current. The dyads can be made by a self-assembly process and each nanoparticle can be controlled to be hydrophobic or hydrophilic by manipulating the capping ligands.  
Recent work by our group indicates that the vertical charge transfer occurs in type II CdSe/CdTe assembly in water solution. In order to make type II CdSe/CdTe dyads at an interface, future work will be directed to study the assembly and photoinduced heterogeneous electron transfer at the liquid|liquid interface, monitored by a four-electrode electrochemistry system (Figure 3).
Figure 3. Four-electrode electrochemical cell