Lead-Free Perovskite Cs2AgxNa1–xBiyIn1–yCl6 Microcrystals for Scattering–Fluorescent Luminescent Solar Concentrators

In recent years, luminescent solar concentrators (LSCs) have gained a renaissance as a pivotal transparent photovoltaic (PV) for building-integrated photovoltaics (BIPVs). However, most of the studies focused on light-selective LSCs, and less attention was paid to the utilization of the full solar spectrum. In this study, a lead-free microcrystal Cs2AgxNa1–xBiyIn1–yCl6 (CANBIC) perovskite phosphor is demonstrated to have bifunctional effects of luminescent down-shifting (LDS) and light scattering for the fabrication of LSCs, realizing light response from ultraviolet (UV) to NIR regions by an edge-mounted Si solar cell. The optimized CANBIC content (30 mg) in an LSC realizes the best optical efficiency (ηopt) of 5.40% and an average visible transmission (AVT) of >50%. This contributes to the improvement in short circuit current density (JSC) up to 1.232 mA/cm2 for the LSC–PV system (one-edge mounted Si solar cell) as a result of the best power conversion efficiencies (PCEs) of 0.463% and 1.852% for the LSC–PV and LSC–4PV systems (four-edge mounted Si solar cells), respectively. An Al foil is applied as a reflection background in the LSC–4PV system, and a champion PCE of 3.14% is realized due to an improved JSC of up to 7.94 mA/cm2 in total. Furthermore, the LSC maintains superior stability under exposure to continuous ultraviolet illumination or in ambient air.