Volumetric 3D printing enabled by triplet fusion upconversion nanocapsules*

One way to achieve volumetric 3D printing, where a vat of polymerizable resin is patterned by light in three dimensions, is to use two-photon photopolymerization (2PP). While this approach has its advantages, high energy ultrafast lasers and slow print speeds hinder widespread adoption. Here, we present an analogous process driven by triplet fusion upconversion (UC). To ensure excellent light penetration through the vat of resin with the high sensitizer/annihilator concentrations required, the UC materials are encased in silica to generate robust nanocapsules for suspension in the resin. By pairing UC nanocapsules and commercially available photoinitiators and resins, we rapidly generate macroscale prints with fine detail.