Sandwiched electrode buffer for efficient and stable perovskite solar cells with dual back surface fields

Summary With the rapid progress of perovskite solar cells (PSCs), both high efficiency and sufficient stability are required simultaneously for their real-life application, wherein interfaces play an essential role. In this work, we develop sandwiched electrode buffer (SEB) with respect to the hole-transport layer (HTL), wherein dual back surface fields are implemented at two interfaces in relevance. The SEB bridges the absorber to the back electrode with the desired band alignment and multi-defect passivation effects, which stabilize the perovskite, HTL, and metal electrodes. Accordingly, planar n-i-p PSCs with SEB achieve an efficiency of 23.9% (certified 23.4%). Notably, they exhibit a remarkable operational stability with only a 3% efficiency decline for 2,000 h maximum power point tracking under 1-Sun illumination. Furthermore, the devices also show excellent thermal stability and humidity stability. Therefore, the SEB configuration boosts both efficiency and stability of PSCs, which paves the way for the commercialization of perovskite optoelectronics.