Effect of Pelargonidin on carrier recombination lifetime of CTS quantum dots

Abstract

In the current work, we have prepared stacks of Copper tin sulphide (CTS)/Pelargonidin core/shell quantum dots on soda lime substrates by SILAR technique. Copper tin sulphide quantum dots were of tetragonal phase matching well with JCPDS 089-4714. The absorption coefficient of the core/shell quantum dots increased while the photoluminescence intensity decreased with increasing shell thickness. Decrease of charge carrier confinement energy due to leakage of wavefunction into the shell is the cause of fall in PL intensity. Three transitions were found in all the samples corresponding to 1Se-1Sh, 1Pe-1Ph and 1De-1Dh transitions using the non-interacting particle model. Charge carrier recombination lifetime of P state was found to be in the order of 100 ns, with lifetime increasing with shell thickness, probably due to the P state being the most occupied at room temperature and decrease of surface trap sites with increasing shell thickness. Owing to the high lifetime of CTS/Pelargonidin core/shell quantum dots, these can be used effectively in solar cells where recombination time is a deciding factor for efficiency and also in bioimaging of living cells and tissues.