Dynamic synthesis of CdTe NRs: Diameter dependent tuning of PL quenching efficiency for sensitive organic vapor detection

Abstract

Cadmium telluride (CdTe) is one of the well-explored semiconductors in the history of material science research, because of its innumerable benefits in all dimensional nanostructures. However, no endeavor has been dedicated as of now to understanding the size-dependent tuning of nonradiative emission efficiency and how it influences the sensitive detection of organic vapors (ethanol and acetone) through photoluminescence (PL) quenching mechanism. Herein, the aspect ratio of CdTe nanorods (NRs) is varied by changing its diameter while keeping the axial length constant through electrodeposition into lab made anodic aluminium oxide (AAO) membranes. The growth kinetics and thermodynamics involved while electrodeposition of CdTe NR in each distinct pore diameter of AAO membrane is studied and reasoned. The surface morphology of variable diameter AAO membranes and NRs, respectively fabricated under various electrochemical parameters are observed through a field emission scanning electron microscope. The relation between NRs dimension and structural parameters like d-spacing, crystallite size, band area ratio, and exciton-phonon ratio are extracted from X-ray diffraction and Resonance Raman spectroscopy. The strongly luminescent CdTe NRs, coupled with their chemical durability and organic molecule affinity displayed a sensitive response of ~12 and 6 ppm to ethanol and acetone vapors in the range of 10–100 ppm as a PL sensor. The carrier lifetime measurement through time-correlated single photon counting spectroscopy endorses the role of increased recombination density with a decrease in the diameter of NRs.