Roadmap on Solar Energy Plasmonics

Abstract Plasmonic nanostructures manipulate light at dimensions much smaller than wavelength, leading to strong electromagnetic field confinement, enhanced light absorption and efficient photocarrier generation. This makes them promising components for future solar energy conversion systems. This Roadmap surveys recent advances and future directions in the application of plasmonic principles to solar energy technologies across nine topical areas. Key themes include the plasmonic enhancement of light harvesting in perovskite solar cells; thermoplasmonic conversion of solar photons into localized heat for chemical transformation; and plasmonic photocatalysis for selective CO₂ reduction and hydrogen evolution. The collection also covers hybrid and ternary plasmonic–semiconductor–MOF architectures, S-scheme chalcogenides for water splitting, mechanistic studies of non-thermal and hot-carrier processes, and advanced electromagnetic and quantum–mechanical modelling of nanoplasmonic systems. Together, these contributions delineate the current state of plasmonic solar energy research and current and future challenges. Throughout the roadmap enhancements are attributed to solar-excited plasmonic mechanisms (hot-carrier transfer, photothermal effects, near-field enhancements, etc). However, the contribution of each mechanism to enhancement is not well understood or easily quantifiable. A key challenge, therefore, is to fully quantify the contribution of each plasmonic mechanism, using both experimental techniques and material modelling, to enable the optimized design of plasmonic platforms. Further challenges relate to the chemical stability of the metals currently used as plasmonic materials, and their high cost. The use of non-metal shells around metal nanoparticles is seen as a promising way to overcome stability issues, while conductive transition metal nitrides are identified as attractive low-cost, chemically stable alternatives to noble metals in the visual-NIR spectrum. Finally, scalable nanofabrication techniques are required to produce efficient, durable, and economically viable plasmonic platforms for sustainable solar fuel and power generation.