| Abstract
| - The electronic conductivity of PbS and CdTe nanoparticle monolayers was examined voltammetrically byusing interdigitated array (IDA) electrodes at the air|water interface. Their band gap energies were estimatedfrom the I−V responses and were very consistent with results obtained from optical measurements as well assolution electrochemistry. For CdTe nanoparticles, the I−V responses were analogous to those of a moleculardiode with reproducible voltammetric behavior after repeated potential cycling. Interestingly, there appearedto be indications of particle surface trap states in the voltammetric responses that correlated with spectroscopicmeasurements. In addition, the band gap of the nanoparticle monolayers could be manipulated by theinterparticle interactions, red shifting with decreasing interparticle separation. In contrast, the electroactivenature of the PbS particles led to the decomposition of the nanoparticles and hence deposition onto the electrodesurface. The resulting voltammetric responses evolved from those typical of the faradaic reactions to a rectifyingfeature of much larger current scales, which finally became linear (ohmic) because of shorting betweenneighboring IDA fingers. In these studies, it was found that photoexcitation played an important role inregulating the current responses, providing a mechanistic basis on which to manipulate the electronic/electricalproperties of semiconductor nanomaterials. The conductivity of the final interfinger deposits was about 2orders of magnitude smaller than that for pure metallic lead, indicating some surface contamination and/orless than perfect crystalline structure.
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