Multicolor-Emissive Carbon Quantum Dots Sensitized into Nanolaminated Piezoelectric Biofilms for Multifunctional Sensing

In response to the evolving applications of intelligent systems, the fluorescent pressure sensor (FPS) has been proposed but usually with complicated structure design. Herein, we develop a multicolor-emissive FPS through simply sensitizing carbon quantum dots (CQDs) into nanolaminated biofilms. The multicolor fluorescence derived from three types of CQDs was successfully implanted into the piezoelectric cucumber pulp slices (CPS), which was subsequently verified to be also feasible in grape peels. The suppression of aggregation-induced quenching in the hybrid film is attributed to the imitated sensitizer/photoelectrode structure (ISP) with two features: (i) the nanolaminated matrix supported uniform distribution of the CQDs and (ii) the interfacial bonding between the CQDs and the matrix. The ISP structure also awakens a charming bridging effect from CQDs, leading to the significantly improved piezoelectric performance of the hybrid films. Due to the suitable size matching degree of 0.85 and the potential adding strong bonding supported by the unique sulfonic acid (SO₃H), the red-emissive CQDs/CPS-based FPS possesses an optimal sensitivity of 38.6 mV N^-1, which is 80.37% higher than that of the pure matrix (21.4 mV N^-1). This renewable hybrid film-based FPS integrates multiple requirements, such as UV perception, tactile perception, and energy harvesting.