Laser-Induced Transfer of Functional Materials

Laser-induced transfer is a patterning method whereby photon-momentum prints target materials from one substrate (the donor) to another (the acceptor). Laser-induced transfer can make flexible electronics, 3D constructions, and nanoparticle patterns. All the metals, semiconductors, and dielectric materials are appropriate for laser-induced transfer. The main advantage of this patterning method is to rapidly and accurately place materials onto a substrate due to contactless transfer and precisely controlled laser scanning. Two mechanisms are commonly used for laser transfer momentum and thermal effect. Momentum-type laser transfer uses the momentum of the photon for the transfer. The thermal effect is another mechanism driving laser-induced transfer Rather than using the momentum of an ultra-short laser pulse, the thermal effect transfer uses the thermodynamic energy generated from the transient local laser heating. The ultra-short laser pulse can create a transient ultra-high temperature, leading to rapid local thermal vaporization. The generated vapor and plasma will rapidly explode and drive the ejection of fragmented donor materials. Some materials will be thermally decomposed when the laser heating is sufficiently strong. When using a picosecond or femtosecond pulse laser, a Coulomb explosion will also occur and contribute to the transfer. According to the thermal sensitivity of the transfer materials, two subcategories of thermally laser-induced transfer have been proposed, including direct transfer and sacrificial-layer-assisted transfer. In the latter, a sacrificial layer called the dynamic release layer can absorb the photon power, generating sufficient thermodynamic energy for transferring highly temperature-sensitive materials, even living cells with narrow temperature variation tolerance.