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.