Efficient Flexible Perovskite Solar Cells Using Low-Cost Cu Top and Bottom Electrodes

Perovskite solar cells (PSCs) are promising technology for flexible photovoltaic applications because of the low cost and good flexibility of the halide perovskite materials. Nevertheless, the use of transparent conductive oxides (TCOs) and noble metals (e.g., Au and Ag) as PSC electrodes is very costly, and TCOs are too brittle for flexible applications. How to fabricate flexible PSCs (FPSCs) with cost-effective and soft electrode materials remains to be a big challenge. Herein, we report the first study of FPSCs using low-cost Cu electrodes. Both the transparent bottom electrode and the opaque top electrode are fabricated with Cu. FPSCs made with such Cu electrodes acquire a champion efficiency of 13.58% (J_sc of 17.79 mA cm^-2, V_oc of 1.031 V, and FF of 74.07%), which retains over 90% after 1000 cycles of bending at a small radius of curvature of 5 mm. The device shows negligible changes in Voc and FF after storage for 10 weeks without encapsulation.