Cu–Fe–S-Based Colloidal Quantum Dotswith Strong and Reversible Luminescence Photobleaching for OpticalData Storage

CuFeS_<i>x</i> (CFS) core–shell quantum dots (QDs) synthesized via a high-temperature colloidal chemistry route demonstrate unusually strong photobleaching of their luminescence under irradiation with blue light. Cw laser irradiation at λ = 440 nm results in a substantial drop in the photoluminescence (PL) output of CFS QDs in a polymeric film down on 80% of its initial value within a few seconds. The PL signal recovers within a relatively short time frame from hours to days, and such a process drastically speeds up by the sample heating to a mild temperature of ca. 50–70 °C. Comparative analysis of CFS, CuInS_<i>x</i>, and mixed CuFeInS_<i>x</i> core–shell QDs demonstrates the important role of Fe atoms in the formation of the nonemissive long-lived traps for photoexcited charges. Polymeric films impregnated with CFS QDs can be potentially used as the optical storage media for graphic or digital information with a multifold write-and-erase capability.