Photoconductivity of Colloidal Quantum Dot Films in Plasmonic Nanogaps

Abstract

We investigate the photoconductivity properties of lead sulphide (PbS) quantum dot ensembles in lithographically tailored gold electrodes with smallest gaps of 15 nm. We demonstrate that quantum dots are reliable nanoscale light/current converters and correlate the measured photocurrents to the quantum dot number, the gap voltage and light irradiance. For the latter, we find a photocurrent power law dependence with an exponent of 2/3. Furthermore, we probe the role of plasmonic effects in the gold electrodes and image by scanning photocurrent microscopy the spatial dependence of photocurrent generation.

Keywords

• quantum dots
• photoconductivity
• plasmonics