In situ synthesis of MAPbX3 perovskite quantum dot-polycaprolactone composites for fluorescent 3D printing filament

The development of functionalized polymer-based filament enables the fused deposition modeling (FDM) 3D-printed materials or structures with a wide range of unique functions. This work explores the use of MAPbX ₃ (MA = CH ₃NH ₃ , X = Cl, Br, I or mixture of them) perovskite quantum dots (PQDs) by harnessing their unique optical properties for the development of fluorescent 3D printing filaments. Firstly, a one-pot strategy for scalable synthesis of MAPbX ₃ PQDs-polycaprolactone (PCL) composite was proposed by in situ formation of PQDs in PCL matrix. To demonstrate the ability for the obtained PQDs-PCL composites to fabricate fluorescent filaments, the effects of filament functionalization on optical properties of PQDs, as well as thermal and mechanical properties of polymer matrix were then comprehensively studied. Owing to the good protective capability of PCL, the synthesized PQDs-PCL composites exhibit comparable PLQY and enhanced UV, water and thermal stability compared to that of pure PQDs. Moreover, high concentration of embedded PQDs in PQDs-PCL composites was obtained with decreasing amount of PCL. The aggregation of PQDs at high temperature combined with the poor interaction between PQDs and surrounding PCL matrix led to the decreased thermal transition temperature and reduced mechanical properties in PQDs-PCL composites relative to pure PCL. The glass transition temperature was found to decrease by 5.5 °C, while the mode of failure changed from plastic fracture for pure PCL to brittle fracture for the highest concentration of PQDs in PCL tested. Consequently, PQD-PCL composites were further processed into fluorescent filaments and further fluorescent objects or structures via 3D printing. Green LED and white LED devices were realized by the combination of UV LED chip with 3D printed MAPbBr ₃ PQD-PCL thin-film, and blue LED chip with MAPbBr ₃ PQD-PCL thin-film and K ₂SiF ₆:Mn ⁴⁺ phosphor, respectively, demonstrating that the PQDs-functionalized 3D printing filaments have great potential in fields of optoelectronic application.