Flexible Perovskite Solar Cells

Since the first report on solid-state perovskite solar cells (PSCs) with 9.7% efficiency and 500-h long-term stability in 2012, PSCs have achieved an amazing power-conversion efficiency (PCE) of 24.2%, exceeding the PCEs of multi-crystalline Si (22.3%), thin-film crystalline Si (21.2%), copper indium gallium selenide (22.6%), and CdTe-based thin-film SCs (22.1%), and are suitable for transforming into flexible solar cells based on plastic substrates. The light weight and flexibility of flexible-PSCs (F-PSCs) allows their use in niche applications such as portable electric chargers, electronic textiles, large-scale industrial roofing, and power sources for unmanned aerial vehicles (UAVs). However, the F-PSCs always exhibit inferior efficiency compared to rigid PSCs, i.e., champion-cell efficiency of F-PSCs is 19.11%, which is apparently lower than that of rigid cells. Also, the world-best module efficiency for rigid perovskite module is 17.18% (30 cm²) higher than that for flexible perovskite module efficiency, 15.22% (30 cm²). Moreover, the F-PSCs have not shown better long-term stability in comparison with rigid PSCs. In this review paper, we investigate fundamental challenges of F-PSCs regarding relatively low efficiency and stability and demonstrate the recent efforts to overcome big hurdles. Also, current attempts for the commercialization of F-PSCs are introduced.