Flexible and lightweight perovskite/Cu(In,Ga)Se2 tandem solar cells

Flexible perovskite/Cu(In,Ga)Se2 (PVSK/CIGS) tandem solar cells (F-PCTSCs) can serve as lightweight and cost-effective power sources suitable for versatile applications; however, technical challenges impede their implementation. In this study, we adopted a straightforward lift-off process based on a polyimide (PI)-coated soda-lime glass (SLG) substrate for fabricating high-performance F-PCTSCs while addressing key technical challenges. The CIGS films grown on a PI-coated SLG substrate exhibited larger grains and higher carrier concentrations compared with their counterparts grown on bare SLG, as well as alleviated charge recombination. These enhancements were attributed to the suppression of alkali metal diffusion by the PI interlayer during the film growth, which resulted in superior device performance. Building on this approach, we fabricated efficient and lightweight F-PCTSCs that delivered a state-of-the-art power conversion efficiency of 23.64% (certified 22.8%) and high power-per-weight of 6.15 W g-1, which is significantly greater than that of PVSK/silicon tandem solar cells (0.65 W g-1).