Electric field enhanced photoluminescence of CdTe quantum dots encapsulated in poly (N-isopropylacrylamide) nano-spheres

Photoluminescence from CdTe quantum dots encapsulated within hydrogel nanospheres can be controlled by the application an external dc electric field. Dynamic light scattering measurement of hydrogel placed under an electric field shows the collapse of the hydrogel sphere from 312 to 180nm due to volume phase transition. Distances between quantum dots placed within the hydrogel sphere can be controlled by the applied field. A 50% enhancement in the PL intensity is observed under the influence of a dc field less than 5 V/cm. A red-shift in the peak PL intensity and emission from larger sized dots indicate energy transfer between the quantum dots. The collapse of gels is reversible and therefore has potential application in non-volatile memory devices. (C) 2008 Optical Society of America