  Color printing at the diffraction limit has been recently explored by
fabricating nanoscale plasmonic structures with electron beam lithography.
However, only a limited color range and constant intensity throughout the
structure have been demonstrated. Here we show an alternative, facile approach
relying on the direct, open-atmosphere electrohydrodynamic rapid nanodrip
printing of controlled amounts of red, green and blue (RGB) quantum dots at a
resolution of 250 nm. The narrow emission spectrum of the dots allows the
coverage of a very broad color space, exceeding standard RGB (sRGB) of modern
display devices. We print color gradients of variable intensity, which to date
could not be achieved with diffraction-limited resolution. Showcasing the
capabilities of the technology, we present a photo-realistic printed image of a
colorful parrot with a pixel size of 250 nm.
