CDs@ZnO multi-core@shell structure: Rational designed versatile platform for multiple wavelength RTP, TADF and lasing in high security anti-counterfeiting

Abstract

The rational design of a versatile platform capable of producing multi-wavelength afterglow carbon dots (CDs) with varied structures remains a significant obstacle, particularly in enabling the concurrent realization of room-temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF). Here, a novel approach is proposed: the chemical encapsulation of CDs within a ZnO multi-core@shell structure to enable dual RTP and TADF emissions under visible light excitation. This is possible because a three-dimensional spatial constraint, coupled with chemical bonding for immobilization, introduces a pivotal role in stabilizing the triplet state within the CDs. Furthermore, CDs with diverse structures are validated to achieve multi-color afterglow emission through this versatile platform, which demonstrates broad applicability. Given the singlet excitons regeneration through the reverse intersystem crossing (RISC) process random lasing is successfully realized from CDs@ZnO. Hence the synergistic integration of RTP, TADF, and lasing construct the multi-levels anti-counterfeiting strategy, greatly enhance the security level. This work not only paves the way for the creation of afterglow materials and lasing media based on CDs but also holds potential for applications in advanced anti-counterfeiting techniques, encryption methods, and optical devices.