Formulation of functional materials for inkjet printing: A pathway towards fully 3D printed electronics

Inkjet printing offers a facile route for manufacturing the next generation of electronic devices, by combining the design freedom of additive manufacturing technologies with tuneable properties of functional materials and opportunities for their integration into heterostructures. However, to fully realise this potential, the library of functional materials available for additive manufacturing technologies needs to be expanded. In this review, we summarise current developments in ink formulation strategies, approaches for tailoring the functional properties of inks, and multi-material processing. Material – process – property relationships are reviewed for emerging functional materials, such as polymers, nanomaterials, and composites, with examples of current state-of-the-art devices. The flexibility of combining inkjet deposition with other existing technologies and a variety of substrates is also discussed reviewing current trends in electronics and optoelectronics, including wearable electronics, sensing, and energy applications. The review offers a comprehensive and systematic overview of ink formulations for inkjet deposition of electronic devices, summarising the challenges and perspectives in the advancement of 3D and multi-functional electronic devices and smart electronics.