Thermally Driven Amorphous-Crystalline Phase Transition of Carbonized Polymer Dots for Multicolor Room-Temperature Phosphorescence

Multicolor carbon dot (CD)-based nanomaterials offer a variety of opportunities for potential applications in bioimaging, optoelectronic devices, and information security. However, it still remains a challenge to modulate the conjugated pi-structure of CDs to achieve multicolor room-temperature phosphorescence (RTP). Herein, the authors present a strategy based on thermally driven amorphous-crystalline phase transition to achieve multicolor carbonized polymer dots (CPDs) with the emission color tunable from green to orange-red. This is the first report on multicolor RTP emission from CDs by means of thermal stimulus. Further investigations reveal that the formation of self-protective covalently crosslinked frameworks and codoping of multiple heteroatoms play a crucial role in the production of RTP. RTP color tunability can be attributed to different crystalline contents of the conjugated pi-domain within CPDs. Potential application of the developed CPDs as printable and writable security inks for advanced multilevel anti-counterfeiting and encryption is demonstrated. This work paves a path for the development of multicolor RTP materials and suggests great potential of CDs in exploiting novel optical materials toward intriguing applications.

Automated summary

This study demonstrates the first multicolor room-temperature phosphorescence emission from carbon dots by utilizing a thermally driven amorphous-crystalline phase transition to achieve tunable emission colors. The development of carbonized polymer dots with potential applications as printable and writable security inks paves the way for the advancement of multicolor room-temperature phosphorescence materials.