A luminescent solar concentrator (LSC) consists of loaded luminophores and a waveguide that can concentrate direct and diffuse sunlight, which is a crucial ingredient for developing solar glasses. In general, the loading concentration in LSCs is strongly restricted (typically <1 wt.%) to mitigate concentration-induced quenching (CIQ), reabsorption losses, and aggregation-induced scattering (AIS). However, this will induce transmission losses in particular for thin-film LSCs. To address all aforementioned issues, large-Stoke-shift LSCs with different loadings are simply prepared based on thiolated gold nanoclusters (GSH-AuNCs) dispersed in the polyvinylpyrrolidone (PVP) matrix. In contrast to conventional luminophores with a severe CIQ effect, photoluminescence quantum yields (PL-QYs) can be significantly enhanced up to %25% (from 0.5 to 1%) even under high loading of %26 wt.%. Such PL-QY enhancement is attributed to the synergistic effects of the suppression of non-radiative relaxation and enhancement of radiative decay processes due to surface ligand-matrix coordination. In addition, our high-loading LSCs also exhibit excellent optical quality and film uniformity without introducing noticeable AIS effects. Thanks to those unique properties, eco-friendly LSCs with high optical density can still hold a high edge-emission efficiency of %70% due to minimal reabsorption and scattering losses, yielding an external quantum efficiency of %15% at the wavelength of 400 nm.