Selective Metallization with a Sn₂P₂O₇ Oxygen Vacancy Laser Sensitizer for Multifunctional Metal Circuits on Polymer Substrates

Laser-induced selective metallization (LISM) has emerged as an effective circuit fabrication technique owing to its masklessness, design flexibility, and high accuracy. Among the LISM, the laser sensitizer plays a crucial role as it directly determines the performance of the obtained copper layer. Therefore, developing new types of laser sensitizers with an excellent LISM effect has emerged as a key research frontier in this field. In this paper, we developed and investigated a new autocatalytic laser sensitizer: tin pyrophosphate (Sn2P2O7). The ultraviolet (UV) laser's photochemical and thermal effects caused the formation of oxygen vacancies (OVs) in the Sn2P2O7 lattice after laser activation, and Sn2P2O7 containing OVs is exposed to the polymer/Sn2P2O7 surface as the active center to an autocatalytically induced electroless copper plating (ECP) reaction. The copper layer obtained on the polymer/Sn2P2O7 after ECP has excellent conductivity (3.03 × 107 Ω-1·m-1) and superior precision (35.58 μm). Furthermore, using Sn2P2O7 as the laser sensitizer allows the preparation of different metal circuit patterns on various 2D or 3D substrate surfaces as well as the fabrication of metal circuits on different substrate surfaces. In addition, the prepared copper layers have been successfully applied in the fields of UV photodetectors and Joule heaters, proving the great potential of LISM using the Sn2P2O7 laser sensitizer in advanced electronic devices.