Stability is the key for long term use of CdSe nanoclusters (NCs) in many applications. For example, photovoltaic devices, which commonly use CdSe NCs suffer from insufficient efficiency due to the decomposition of NCs in an aqueous medium. Currently Na2S is the most commonly used electrolyte, which captures the photo-generated holes and increases the stability. However, Na2S increases the solution pH ~13 during the photocurrent measurement and at this pH, CdSe NCs undergo decomposition. Therefore, a system should be developed where photocurrent measurement can be done in organic solvent/electrolyte medium using an organic hole scavenger. Recently we have developed a synthesis of PEG-thiolate protected CdSe NCs with unique solubility properties that allow the NCs to dissolve in a variety of solvents such as acetonitrile, ethanol, methanol, dichloromethane. We believe that these newly synthesized CdSe NCs show promise for the use in photovoltaic devices to increase the efficiency since organic solvents could be substituted for the aqueous medium currently used. However, in order to design efficient photovoltaic devices with enhance stability, it is important to study the stability of these NCs in a variety of organic solvents and compare these results with the NC's stability in an aqueous medium. Herein we present an investigation of the influence of organic solvents and thickness of the surface passivating ligands on the stability of CdSe NCs. We have used alcohol, chlorinated, and coordinating solvents due to their diverse polarity and electrolyte ion mobility. Time dependent stability of these CdSe NCs was monitored over 48 h under benchtop conditions such as light/air, light/N2, dark/air, and dark/N2.

Influence of organic solvents and surface passivating ligands on the stability of CdSe nanoclusters

246th National Meeting (2013)

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