Quantum-Dot-Mediated Light Field Imaging by Photocurrent Scanning Force Microscopy

Light field distributions on sample surfaces are mapped by detecting the photocurrents locally induced in a monolayer of colloidal perovskite-capped PbS quantum dots with a conductive scanning force microsope. The signal levels depend on the illuminating light irradiance according to a power law and the spatial resolution is found to be bias-dependent in the range of 30-100 nm. We image, first, the Airy intensity pattern of a tightly focused laser beam and, second, the light field distribution in a plasmonic nanoparticle array. With isotropic light absorption and the option of tailoring quantum dots for specific charge generation and transport properties, quantum dots can provide a reliable and generic current read-out scheme for light field imaging, detection, and sensing.