Cerium oxide nanoparticle as interfacial modifier for efficient and UV-stable perovskite solar cells

Ultraviolet (UV) illumination can induce the generation of defects at the interface of perovskite and commonly used electron transport materials (ETMs, such as TiO2 and SnO2) in perovskite solar cells (PSCs). This further increase the interfacial charge recombination and accelerate the decomposition of perovskite film, resulting in the attenuation of device efficiency and stability. Here, a cerium oxide (CeOx) nanoparticle with an average size of 18.66 nm is proposed as a novel mesoporous material to modify the interface of ETM and perovskite. The CeOx mesoporous layer with higher electron mobility and more suitable band energy level facilitates charge transfer from perovskite layer. As expected, the mesoporous CeOx based PSCs exhibits an improved power conversion efficiency up to 23.15% (22.57% for control device). More importantly, the mesoporous CeOx layer (about 70 nm) can realize the effective absorption of UV light, to efficiently improve the UV light stability of PSCs and the overall stability of the devices. The unencapsulated devices with mesoporous CeOx maintained almost 90% of initial efficiency after 850 h under UV illumination. This work provides a new approach to fabricate the efficient and UV stable PSCs by introducing the mesoporous CeOx layer.