Tunable luminescence of Cu-In-S/ZnS quantum dots-polysaccharide nanohybrids by environmentally friendly synthesis for potential solar energy photoconversion applications

Highlights: • New quantum dot/polysaccharide (Cu-In-S/ZnS-CMC) nanostructures were produced. • Cu-In-S/ZnS-CMC core-shell nanohybrids were produced by green aqueous process. • CIS QDs with tunable emission properties by non-stoichiometric proportions (Vis-NIR). • Passivation of surface defects of CIS QDs by ZnS layer increased QY by 1500% (ZCIS). • TiO₂ sensitized ZCIS QD nanostructures proved Vis light photoelectrochemical activity. Colloidal semiconductor nanomaterials (QDs) have been systematically investigated as innovative alternatives for green energy production through solar photoconversion devices. Thus, we developed novel fluorescent QD nanostructures based on Cu-In-S (CIS) quantum dot core and ZnS layer (ZCIS) stabilized with carboxymethyl cellulose (CMC) biopolymer ligand for potential applications in solar energy photoconversion. The physicochemical, optical, morphological, and surface properties of the nanostructures were comprehensively characterized by TEM-EDX, AFM, SAED, XPS, XRD, FTIR, DLS, and zeta potential analyses. The results demonstrated that monodispersed CIS QDs (size 3.5 nm) were produced with adjustable emission properties spanning from visible to NIR by altering the concentrations of metallic cations and sulfides. Moreover, the quantum yield presented a drastic enhancement of over 1500% due to the amalgamation of chemical composition and the passivation of surface defects by the formation of quaternary nanostructures (ZCIS). As a proof of concept, a solid-liquid junction solar cell was built based on the photoanode composed of TiO₂ sensitized by ZCIS-CMC nanohybrids, which proved photoelectrochemical activity upon visible light irradiation. Thus, these nanohybrids produced strictly via green chemistry colloidal process can be envisioned as promising candidates for the development of solar cells based on quantum dot-sensitized nanostructures.