Universal Intermolecular Energy Transfer Strategy for Extending Initiator Libraries of Photoinhibited Multiphoton Lithography

Photoinhibited multiphoton lithography allows for high-precision nano additive manufacturing of arbitrary three-dimensional (3D) microstructures. However, its application is severely limited by the scarcity of effective initiators, as most conventional multiphoton lithography initiators lack photoinhibition capacity due to unavoidable single-photon absorption. Herein, we report a universal intermolecular energy transfer strategy that can deplete S₁ state initiator molecules excited by single-photon absorption, thereby mitigating single-photon absorption-induced unwanted photopolymerization and shifting the role of the initiator from photopromotion to photoinhibition. As a result, the initiators for photoinhibited multiphoton lithography can be easily extended. Utilizing multispectral analysis and density functional theory calculations, we have elucidated the underlying mechanisms of photopromotion to photoinhibition by exploring intramolecular charge transfer and intermolecular energy transfer. This strategy has been validated with a range of commercial initiators, showcasing its versatility and effectiveness. Furthermore, the resolution of two-dimensional (2D) and 3D structures created through this strategy has been greatly improved while maintaining a high writing speed. These advancements have propelled the field of high-precision nano additive manufacturing, opening up new possibilities for the fabrication of intricate nanostructures.