Gradient-graphene-enabled directional photothermal regulation for self-aligned laser transfer printing.

Laser-assisted transfer printing has gained attention for integrating microdevices on unusual substrates. However, conventional technologies exhibit limited fault tolerance during laser-matter interactions, reducing transfer accuracy due to unavoidable irradiation deviations. We report a self-aligned laser transfer (SALT) that enables high-precision, programmable assembly of microchips without precise laser-to-die alignment. A thermal conductivity gradient carbon (TCGC), with an upper graphene layer and lower amorphous carbon layer, is embedded in the stamp via excimer laser self-limited carbonization of polyimide. The TCGC converts asymmetric light input into uniform heat output under non-uniform/misaligned infrared laser irradiation, whereas the upper graphene layer absorbs heat from the lower amorphous carbon and rapidly conducts heat laterally, ensuring uniform heat distribution of the underlying adhesive layer. This guarantees synchronous chip release at all adhesive sites, mitigating transfer deviations. Additionally, periodically arranged, grayscale-controlled TCGC can be fabricated by modulating excimer laser parameters during carbonization, thereby enabling selective microchip release without pre-planned scanning paths. SALT achieves excellent size compatibility ( < 100 micrometers) and high tolerance for irradiation deviations (transfer accuracy <5 micrometers). Demonstrations of RGB micro-LED display highlight its self-aligned and batch-selective capabilities.