Luminescent solar concentrators based on environmentally friendly tripodal D–(pi–A)3 triarylamine luminophores

Luminescent solar concentrators (LSCs) offer a promising approach for efficient solar light harvesting and energy conversion, while possessing favorable aesthetic characteristics that make them particularly interesting for integration in the built environment. Although this technology has witnessed enormous progress in the past decade, different open challenges still interfere with the large-scale use of LSCs, including the limited spectral absorption of luminophores, the presence of non-negligible photon reabsorption losses, and the limited photostability of materials and devices. Star-shaped triphenylamine derivatives emerge as promising luminophore candidates due to their tunable optical properties and synthetic versatility. This study introduces a series of tris-(4-phenylethynyl-phenyl)-amine-based molecules with varied peripheral groups, obtained at room temperature through a sustainable multistep synthetic method characterized by an E-factor <190. The symmetrical D-(pi-A)(3) structure of these molecules is designed to enhance their optical response in view of their application as luminescent species in LSCs, as also corroborated by density functional theory calculations. Their incorporation in poly(methyl methacrylate) matrices at increasing concentration enables the systematic investigation of their optical characteristics and their photonic and photovoltaic response in LSC devices under simulated sunlight, demonstrating high average visible transmittance (similar to 90%) and maximum internal and external photonic efficiencies as high as similar to 50% and similar to 5%, respectively. The particularly straightforward and affordable synthetic pathway developed to achieve these luminophores, together with the excellent performance of the corresponding LSC devices and their favorable aesthetic characteristics, make these systems promising candidates for future building-integrated LSC applications. In particular, their narrow absorption bands and high photoluminescence efficiencies make them especially promising for applications in transparent LSCs, where high visible light transmittance is prioritized over broad absorption, alongside energy harvesting.