Spectroscopic matching in semitransparent solar cells with I–Br mixed halide perovskite and DMD electrode

Balancing light transmittance and power conversion efficiency (PCE) remains a major challenge for semi-transparent perovskite solar cells (ST-PSCs), particularly for applications in building integration and agrivoltaics. In this work, dielectric–metal–dielectric (DMD) electrodes based on WO₃/Ag/WO₃ as a high-performance alternative to conventional semi-transparent gold (Au) contacts were integrated into bromide-rich formamidinium lead halide perovskites, with a systematic study across halide compositions from pure bromide to pure iodide. The DMD electrodes consistently enhanced photovoltaic performance and optical quality, achieving an average visible transmittance (AVT) of 43.63%, light utilization efficiency (LUE) of 3.05%, and a PCE of 7% for FAPbBr₃-based cells. An optimal composition with 47% bromide yielded a balanced performance with 24% of average visible transmittance (AVT), 2.12% LUE and ∼9% PCE. Rather than simply increasing bromide content to widen the bandgap and enhance transparency, this study shows that there is an optimal spectral alignment that maximizes transmittance, photocurrent extraction and color. In addition, replacing Au with WO₃/Ag/WO₃ significantly reduces the environmental footprint, as confirmed by life cycle assessment. This study highlights a photonic design approach to advancing efficient, sustainable, and visually appealing ST-PSCs for next-generation energy applications.