Laser-assisted forward transfer of multi-spectral nanocrystal quantum dot emitters

We report in this paper the development of a novel laser-transfer scheme to integrate laterally arrays of light-emitting pixels made of semiconductor nanocrystal quantum dots (NQDs). The nanocrystal composition and size can be tailored such that the luminescence emission of the quantum dots in each device pixel constitutes a distinctive spectral channel of narrow bandwidth. An ultrathin film of photosensitive triazene polymer (TP) has been employed as the sacrificial layer whose decomposition upon UV excitation delivers the bilayer structure of nanocrystal and metal films to the substrates. The ejected plume of the decomposed photosensitive polymer produces a thrust force to ensure the conformal contacts between the NQD layer and the bottom hole transport layer. A 6 × 6 red and yellow matrix with pixel sizes of 800 µm is demonstrated. This technique opens up the possibility of developing small, on-chip light sources featured with multiple wavelength channels over a desired spectral range as well as the flexible substratum.