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We demonstrate near-field fluorescence excitation and imaging with a quantum dot (QD) light emitting diode (QDLED) integrated at the tip of a scanning probe. The tip-embedded QDLED is employed in a near-field scanning optical microscopy setup to directly excite a secondary colloidal QD sample. Electrically pumped QDs enable multi-color, self-illuminating probes with no conventional optics needed for light coupling. Monolayer QDs stamped at the very tip of a micromachined silicon probe facilitates precise position control of the ultra-thin (10–15 nm) light source. Sensitivity of fluorescence intensity to the QDLED–QD sample distance was measured down to 50 nm order, demonstrating spatially resolved imaging.

The combination of lithographic patterning and nanostamping methods makes it possible to accurately define diffraction-limited multicolor (wavelengths 560–620 nm) light sources on a silicon substrate. We demonstrate a postprocessing technique that utilizes standard photolithography process to pattern the cathode of top emitting diode. Correlation of electroluminescence, photoluminescence, and atomic force microscopy topography showed that the emission region is well defined through the robust multiscale patterning techniques, with the fineness of the emitting area mainly limited by the point spread function of the observing microscope.