Passivating SnO₂/perovskite interface via guanide hydrochloride toward efficient and stable n-i-p perovskite solar...

Nonradiation recombination of interfacial carriers is a key factor hindering the improvement of efficiency and stability of perovskite solar cells (PSCs). Here, we report an effective electron transport layer/perovskite interface regulation strategy. By introducing the multifunctional molecule guanidine hydrochloride (GCl) on the surface of SnO₂, we can enhance the electron extraction between SnO₂ and perovskite and promote the growth of high-quality perovskite films. GCl is anchored on the surface of SnO₂ and interacts with undercoordinated ions in perovskite. The experimental results show that GCl has interaction with both SnO₂ and perovskite layer, and a "bridge" connection is formed between the two layers. This strategy not only passivates the SnO₂/perovskite interface defects, improves the perovskite crystallization quality, but also helps to reduce the interface charge accumulation. More importantly, the PCE of GCl passivated device reached 21.63 %, which was much better than that of control device (19.56 %). In the air environment, after 30 days at room temperature, the GCl modified unpackaged device maintained 83 % of its initial efficiency. Therefore, interface modification with GCl is an effective strategy to improve the interface state, improve the crystallization quality and obtain high-performance PSCs.