Reversible laser-printing perovskite quantum dots in glass via lanthanide doping
Femtosecond laser irradiation enables spatially resolved printing of CsPbBr3 perovskite quantum dots (PeQDs) within borosilicate glass, yet the write-erase-recovery cycle is governed by glass network connectivity, a parameter that remains poorly quantified. This work demonstrates that lanthanide oxide doping (Ln2O3, Ln = La, Gd, Lu) modulates the silicon-oxygen network and controls in situ PeQD formation. Optimal Ln2O3 concentration disrupts bridging oxygen (Si-O) bonds, yielding a looser network that lowers the crystallization barrier and permits complete laser erasure. Over-doping induces a rigid network that prevents erasure. Erased regions autonomously regenerate via water molecule invasion, with recovery time dictated by lanthanide type and concentration. At 2 mol% Lu2O3, the Si-O tensile vibration at 1039 cm-1 exhibits maximal frequency and intensity reduction, correlating with the shortest self-recovery time in air. The reversible luminescence survives multiple cycles without degradation, enabling 4x6 code arrays and Quick Response codes that are invisible under daylight, decodable under UV, and selectively erasable by low-power fs laser for anti-counterfeiting. This mechanism offers a viable route for critical information encryption and decryption.