Quantum dot solids are achieving ubiquity as the active material in photovoltaics, photodetectors, and LEDs. Their tuneable bandgaps, which confer absorptivity throughout the visible and near-IR regions of the spectrum, and their solution processability, which confers potentially low generation costs, are what have made them widely sought after for device applications. Optimal device incorporation requires an understanding of the energetics at play when a quantum dot solid comes into contact with a metal electrode. Towards understanding the nature of such contacts, we employ scanning photocurrent microscopy. This technique allows for the visualization of current signal distributions in planar quantum dot devices. We investigate the Ohmic and Schottky type barriers formed when a PbS quantum dot film makes contact with a Au or Ti electrode, respectively. We also investigate methods for improving current extraction in these materials.

Visualizing electric fields in quantum dot devices

244th National Meeting (2012)

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