Organic-inorganic hybrid halide perovskites are an interesting class of materials that have excellent semiconductor properties, and demonstrated promising applications on many fields, such as solar cells, water photolysis, light emitting diodes, and amplified spontaneous emission. So far, the device lifetime is still short, and this is an important key issue faced for all researchers in this field. The deep understanding of their durability and degradation mechanism is critical and necessary toward future applications.
Towards development of efficient and long-term stable perovskite solar cells (PSCs), we firstly studied the relationship between crystallization, morphology, device architecture, efficiency and durability of encapsulated PSCs. Furthermore, the degradation mechanism of the devices was elucidated by different experimental methods. The well crystallized and fully covered perovskite layer improves not only power conversion efficiency but also long-time durability. Compared to a widely used silver counter electrode, lithium fluoride/aluminum and gold electrode-based PSCs demonstrated better durability owing to less chemical degradation and interface changing. We also confirmed that the amount of accumulated charge carriers induces the degradation of the PSCs, which was proved by a thermally stimulated current technique. Finally, we realized a planar PSC with excellent durability by improving device encapsulation and optimizing device structures.
1. M. Grätzel, Nature Materials 2014, 13, 838-842.