The rise of flexible perovskite tandem solar cells: configurations, progress, challenges, and future frontiers

The flexible perovskite tandem solar cells incorporate multijunction device architectures on flexible substrates, enabling simultaneous increases in output voltage and energy density while maintaining low weight and mechanical compliance. These characteristics are well suited to high specific power photovoltaic applications and energy systems requiring adaptable form factors. This review presents a comprehensive summary of recent progress in flexible perovskite tandem solar cells, with a focus on four representative configurations: perovskite/silicon, perovskite/perovskite, perovskite/CIGS and perovskite/organic tandem systems. Through a systematic organization of reported device efficiencies over different development stages and a focused discussion of representative device demonstrations for each architecture, this review summarizes the principal approaches adopted across different technological routes. Despite continued progress in device efficiency and structural feasibility, the implementation of multi-material and multi-interface tandem architectures on flexible substrates still faces several persistent challenges. On this basis, this review further outlines prospective research directions for flexible perovskite tandem solar cells from the perspectives of material selection, interface and device architecture design, and scalable manufacturing routes. This review is intended to provide a broader perspective and practical guidance for the development of flexible perovskite tandem solar cells.