Stretchable CMC-Na/QD/PU composite film with high photoluminescence intensity via polyelectrolyte-colloidal complex

To meet the requirements of wearable displays, stretchable quantum dot (QD) composite films with robust mechanical and photoluminescence (PL) properties are highly demanded. Polyelectrolytes strongly adsorb on QDs to increase the stability of colloids and also form physical or chemical bonds with the polymer resin. Herein, a sodium carboxymethyl cellulose (CMC-Na) stabilized colloidal CdS@ZnS QD-polyurethane (PU) complex was successfully designed by fine-tuning the concentrations of CdS@ZnS QDs, CMC-Na, and PU to realize the simultaneous enhancement of the PL intensity and mechanical strength of the CMC-Na/QD/PU composite film. Polyelectrolytes and PU play unique roles in the stability and mechanical strength of the system, respectively. The CMC-Na/QD/PU composite film achieved a PL intensity of 3 × 105, a maximum tensile strength of 10.8 MPa, a breaking elongation of 733%, and recyclability, demonstrating great potential for producing flexible, stretchable, and sustainable photovoltaic devices.