Centimeter-Scale Curing Depths in Laser-Assisted 3D Printing of Photopolymers Enabled by Er3+ Upconversion and Green Light-Absorbing Photosensitizer

Photopolymer resins used in stereolithographic 3D printing are limited to penetration depths of less than 1 mm. Our approach explores the use near-infrared (NIR) visible upconversion (UC) emissions from lanthanide-based phosphors initiate photopolymer crosslinking at a much higher depth. This concept relies on invisibility windows and non-linear optical effects achieve selective photopolymers. SLA resin formulation capable absorbing light region (420–550 nm) was developed, order take advantage efficient green-UC Er3+/Yb3+ doped phosphor. NIR-green UC shows versatility enhancing curing laser patterning. For instance, structure with depth 11 ± 0.2 mm, cured width 496 5 µm aspect ratios over 22.2:1 single pass via UC. The reported approached 39 Therefore, this technique would allow up 4 cm. Moreover, it also demonstrated that can cross-linking directly focal point. potential NIR-assisted as low-cost method for direct writing volume printing.