Luminescent solar concentrators (LSCs) have been widely considered to be promising large-scale sunlight collectors for photovoltaics (PV) due to their low cost and applicability to building-integrated photovoltaics (BIPV). However, low quantum efficiency and small Stokes shift of luminophores often deteriorate the performance of LSCs. In this work, Cu₄I₆(pr-ted)₂ nanoparticles (Cu₄I₆(pr-ted)₂ NPs) (where pr-ted is 1-propyl-1,4-diazabicyclo[2.2.2]octan-1-ium) with a large Stokes shift of 1.04 eV and ultra-high photoluminescence quantum yield (PLQY) of 92.2% were synthesized and used as the luminophore to fabricate LSCs. At the same time, the LSCs based on carbon dots (CDs) with a high PLQY of 91.1% were prepared to construct the tandem LSCs, which could further enhance the optical conversion efficiency (η_opt) of the LSC. The as-prepared semi-transparent tandem LSCs based on Cu₄I₆(pr-ted)₂ NPs and CDs (dimension: 5 × 5 × 0.2 cm³) achieved η_opt of 6.40%, which is superior to that of LSCs reported previously with the same size. The as-fabricated LSCs also show a very good stability. The results indicate that these eco-friendly luminophores possess a great potential for fabricating high-performance LSCs for BIPV systems in the future.