Electrophoretic Deposition of CdSe Nanocrystals in Quantum Dot Sensitized Solar Cells
Wednesday, November 2, 2011, 9:20 am, Room 103
Electrophoretic deposition (EPD) of nanocrystal thin films from the solution phase has received increasing attenion due to its simplicity and ability to rapidly create controlled thickness films. In this presentation, we wil discuss the impact of solvent choice, deposition time, and eletrode voltage on the properties of CdSe nanocrystal films deposited by EPD for solar cell applications.
While hexanes are a commonly used solvent for depositing CdSe nanocrystals, resulting film formation by EPD is often not reproducible for different batches of nanocrytals. In this work, we report that adding acetone to solutions of nanocrystals in hexanes enables the consistent deposition of CdSe nanocrystal thin films of controllable thickness. These films form within a few seconds and require comparatively low electrode voltages for the deposition process. The addition of acetone appears to mitigate the effects of impurities in the precursor chemicals, the presence of solvents left over from nanocrystal synthesis, and variable environmental conditions that may otherwise compromise the quality of the resulting EPD nanocrystal films.
Quantum dot sensitized solar cells have been fabricated using the EPD process with CdSe nanocrystals solvated in hexanes with acetone. By modifying the EPD parameters, both the density and thickness of the nanocrystals films deposited on titanium dioxide coated ITO slides were affected. We will discuss the relationship between the EPD parameters and the resulting I-V characteristics and efficiency of the CdSe nanocrystal sensitized solar cells. Preliminary studies suggest that proper choice of EPD parameters can lead to more than one order of magnitude improvement in the solar cell performance metrics.