Unveiling the Carrier Dynamics in Plasmonic and Nonplasmonic CuInS Nanocrystals

In the present investigation, we have synthesized plasmonic and nonplasmonic copper indium sulfide (CIS) nanocrystals (NCs) by changing the copper to indium ratio and compared their charge carrier dynamics. Transient studies were performed at above (400 nm) and below band gap (800 nm) energy. Spectral analysis concludes that intraband transition plays a major role for plasmonic CIS NCs, even exciting upon 400 nm excitation. The NCs (plasmonic and nonplasmonic) follow different relaxation pathways; hot carriers in plasmonic CIS opt to relax via phonon mediated relaxation, whereas the charge carriers generated in nonplasmonic CIS NCs follow a defect mediated relaxation process. Owing to these different relaxation pathways, charge carriers in plasmonic CIS NCs exhibit slower decay dynamics in the longer time scale as compared to nonplasmonic CIS NCs. Our findings provide insight into the carrier dynamics of both CIS NCs and can guide the design of optoelectronic devices based on these materials.