Luminescent solar concentrators (LSCs) are photovoltaic devices that harvest sunlight and concentrate photons through the processes of photon absorption, luminescence, and waveguiding. It comprises a planar waveguide integrated with luminophores, and solar cells are mounted at the waveguide edges. Generally, direct, and diffuse incident sunlight is absorbed by the luminescent species and re-emitted in high wavelength towards the solar cells, and they have converted them as electricity. Such LSCs can lower the cost of electricity when replacing normal house windows by them. In LSC, dyes, polymers, and quantum dots can be used as luminophores. However, finding a heavy metal free environmentally friendly, and stable luminophore is a tricky challenge in the LSC application. Cs₂AgBiBr₆ is a heavy metal free stable double perovskite, and it has exhibited luminescent properties that are well matched for the LSC application.

For the very first time, Cs₂AgBiBr₆ double perovskite is used as luminophores, and integrated LSC exhibited excellent optical and photovoltaic properties. Cs₂AgBiBr₆ coated glass plate was used to analyse the structural, optical studies and fabricate the LSC. X-Ray diffraction analysis (XRD) confirmed that the targeted material is well formed. Scanning electron microscopy (SEM) and Energy-dispersive X-ray (EDX) spectroscopy results suggest that the material is uniformly coated on the glass plate. The optical study revealed that the absorption maxima located around 440 nm and emission at 620 nm. Finally, photovoltaic properties were measured under air mass (AM) 1.5 conditions (100 mWcm⁻², 1 sun) and the optimized device with an active area of 16 cm² (G=4) exhibited a short-circuit current (I_LSC) of 9.5 mA, a short circuit current density (J_LSC) of 0.60 mAcm⁻², an open-circuit voltage (V_OC) of 0.51 V and a fill factor (FF) of 0.74. When the silicon solar cell was directly exposed to 1 sun illumination light, it showed I_cell of 140.0 mA, J_cell of 35.13 mAcm^-2, V_OC of 0.61 V and FF of 0.69. The calculated maximum power conversion efficiency () and optical efficiency ( values for the fabricated LSC are 0.21% and 1.70%, respectively. This is the highest values reported ever for the Cs₂AgBiBr₆ double perovskite integrated luminescent solar concentrators.

Key words: Double perovskite; Luminescent solar concentrators; Cs₂AgBiBr₆