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The electronic and optical properties of conjugated polymers (CPs), that lead to applications spanning from light-emitting diodes, LEDs, to photovoltaic diodes, PVDs and field-effect transistors, FETs, and photonic applications, are controlled both by the primary molecular structure and by supramolecular interactions, just as secondary and tertiary structures are fundamental to the function of proteins. The ability to manipulate the local molecular environment and molecule-molecule contacts is crucial to access fundamentally new classes of organic functional materials with unprecedented performance. Non-covalent interactions affect properties as diverse as lasing and electrical transport, in addition to chemical and mechanical stability. Accurate control of such interactions is needed to allow optimum exploitation of molecular materials, not only in today’s most common optoelectronic devices, such as LEDs, FETs, and PVDs, but also in emerging “photonics” applications. A notable example of supramolecular control is afforded by conjugated rotaxanes that allow a high degree of control in the manipulation of the optical and photonic properties of conjugated polymers. Conjugated rotaxanes feature strongly reduced charge dissociation and polaron formation, which lead to unprecedented ultra-broad gain bands in blends of rotaxanes with emissive conjugated polymers. This result is of crucial interest to both optical amplifiers and lasers. Similarly, perylene bisimides (PBIs) are known for their outstanding fluorescence (many derivatives have quantum yields (QY) of 100%) and photostability. Crucially, by supramolecular design, in particular involvement of H- bonds, highly fluorescent J-aggregates for this class of dyes could berealized. These show fluorescence QY close to unity and exciton ranges up to 70 nm. Hybrid organic-inorganic perovskites are also currently attracting burgeoning interest for both their extremely promising PV efficiencies (up to 15%) and optically-pumped lasing. They are also supramolecular structures, in which an organic salt (such as methylammonium iodide) is non-covalently encased in an inorganic perovskite and may provide a solution to the difficulties due to intrinsic losses from bimolecular annihilation and the conflicting requirements of high charge carrier mobility and large stimulated emission in wholly conjugated systems or to the challenges related to Auger losses and charge transport in quantum dots.