Breakthroughs in science and technology have repeatedly been driven by new and innovative materials. Where size, shape and compositional effects on the functional properties of nanomaterials have been widely explored, the influence of the crystal phase received less attention. The ability of a material to adapt multiple lattice structures, i.e. structural polymorphism, allows tuning of the functional properties (chemical, electrical, and optical) for specific applications. The multipartner FuEPoNa project brings together complementary expertises and research interests and aims to unravel the processes and conditions at the origin of polymorph induction with the ultimate goal of developing rational strategies to control their formation (polymorph selection), and their stabilization, as well as to investigate their functionalities. The materials under investigation range from perovskites and 2D layered materials to allotropic noble metals, with a focus on engineering their functional properties. The proposed materials research goes hand in hand with the continued development, improvement and integration of complementary state-of-the art characterization techniques of the different partners giving insight in structure-function relationships from the atomic scale to long range bulk organization. Via this synergistic approach the applicants will realize novel materials, with a potential for applications in photovoltaics, lighting, electronics, chemical sensing or diagnostics.