The immense technological prospects of creating nanotechnologies that utilize precisely programmed variation in quantum dot (QD) size-dependent properties have intrigued scientist and engineers for years. Despite remarkable advances in the synthesis of colloidal QD with tunable size, shape and composition, the development of enabling technologies in which size-tuned building blocks are patterned with well-defined spatial resolution have lagged behind. In particular, colloidal semiconductor QDs have been proposed for the development of low-cost optoelectronic devices including light-emitting diodes (LEDs). Much of the promise of these materials derives from their size-dependent, and hence tunable, properties.
Our manuscript reports how laser stripe annealing of CdSe QD thin films can yield structures with precisely programmed variations in QD size. We demonstrate that the size-tuned PL emission can be tuned throughout the visible range with a micrometer spatial resolution in a single processing step. Through precise control of the annealing temperature and step, we discovered that QD sintering is a kinetically limited process with a constant activation energy over two orders of magnitude.
To underscore the broader technological implications of our work, we show how periodic modulation of the QD PL properties via laser annealing can change the CIE coordinates of the QD film emission; this enables spatially programmable emission from QD thin films formed from a single feedstock. We illustrate CdSe QD as a proof of concept, we believe that both fundamental kinetic studies as well as periodic property manipulation for applications can be extended to a wide range of nanomaterials with size dependent properties.
Check out the full paper here :/doi/10.1021/acs.nanolett.5b03918