Microstructured optical coatings for climate crisis mitigation

In the face of the global energy and climate crisis, multifunctional optical coatings have become crucial for harvesting solar energy and reducing energy consumption. This review examines recent developments in microstructured optical coatings designed based on geometric optics principles, highlighting their role in two key areas: energy harvesting and energy saving. In the first category, microstructured surfaces enhance photovoltaic performance through improved sunlight steering and capture. In the second category, they enable passive radiative cooling by efficiently emitting heat as thermal radiation while transmitting or reflecting solar radiation. Compared to nanostructured coatings, microstructured designs offer distinct advantages for large-area applications, including compatibility with scalable fabrication techniques and precise, angle-selective optical control. The review covers both horizontal (roof- or ground-mounted) and vertical (building-integrated) configurations, underscoring how each configuration demands specialized microstructural strategies to address different incident sunlight conditions and thermal management challenges. Through a detailed survey of state-of-the-art designs and materials, this review highlights the potential of microstructured optical coatings to advance sustainable energy technologies and gives insight into their role in mitigating global energy and climate crises.