Simultaneous dual-interface modification based on mixed cations for efficient inverted perovskite solar cells with excellent stability

The interfacial modification is crucial for achieving high efficiency and stability in perovskite solar cells (PSCs). Here, we have developed a concise and efficient dual-interface passivation strategy by incorporating mixed cations of phenylethylammonium iodide and methylammonium iodide (PEAI and MAI, denoted as PMI) at both the interfaces of the electron and hole transport layers (HTL). The buried interface enhances HTL wettability and improves perovskite crystallinity, thereby enhancing its performance. Simultaneously, modifying the top surface of the perovskite effectively reduces defects and nonradiative recombination losses. As a result, inverted PSCs exhibit improved VOC, JSC, and FF, leading to a peak PCE of 24.20 %. Compared to the control device (PCEmax = 21.78 %), there is an ∼ 11.11 % enhancement in PCE. Importantly, the passivated PMI-based devices demonstrate exceptional stability even under harsh conditions of 60 °C and 35 % RH. After 1440 h, their PCE retains an impressive 75.3 % of the initial performance, showcasing a remarkable improvement of 21.2 % compared to the control devices (62.1 %). The observed stability exceeds previous studies on PTAA-based inverted PSCs as the active layer.