Post consumer expanded polystyrene as an optical-grade host for lanthanide-doped luminescent solar concentrators
The transition toward net-zero buildings has increased interest in building-integrated photovoltaics (BIPV). Luminescent solar concentrators (LSCs) are particularly attractive due to their transparency, colour tunability, and seamless architectural integration. Yet most LSCs rely on virgin polymers, including polystyrene (PS), a fossil-derived polymer. Expanded polystyrene (EPS) waste is difficult to recycle because of degradation, contamination, and low material value. This study addresses this challenge by converting post-consumer EPS into an optical-grade matrix for LSCs, giving a second life to a hard-to-recycle plastic. Recycled PS (r-PS) was doped with two lanthanide complexes — Eu(TFNB)3Phen and Tb(4BBA)3Phen — and analysed structurally and photophysically. The r-PS retained high transparency and achieved quantum yields of 0.53 ± 0.05 (Eu) and 0.40 ± 0.04 (Tb). Its mechanical properties were preserved, enabling fabrication of functional LSCs with power conversion and optical efficiencies of (0.013 ± 0.001)% and (1.2 ± 0.1)%, respectively. The devices also exhibited dual-mode thermometric sensitivity up to 3.9 ± 0.6 % °C−1. A life-cycle assessment showed significant reductions in acidification, terrestrial eutrophication, and resource use when virgin PS is replaced with r-PS.