Multi-photon in situ synthesis and patterning of polymer-embedded nanocrystals

The in situ synthesis and patterning of CdS nanocrystals in a polymer matrix is performed via multi-photon absorption. Quantum-sized CdS nanocrystals are obtained by irradiating a cadmium thiolate precursor dispersed in a transparent polymer matrix with a focused near infrared femtosecond laser beam. High resolution transmission electron microscopy evidences the formation of nanocrystals with wurtzite crystalline phase. Fluorescent, nanocomposite patterns with sub-micron spatial resolution are fabricated by scanning the laser beam on the polymer-precursor composite. Moreover, the emission energy of the CdS nanocrystals can be tuned in the range 2.5-2.7 eV, by changing the laser fluences in the range 0.10-0.45 J cm -2. This method enables therefore the synthesis of luminescent, CdS-based composites to be used within patterned nanophotonic and light-emitting devices