A Eu3+-Eu2+ ion redox shuttle imparts operational durability to Pb-I perovskite solar cells

By Ligang Wang, Huanping Zhou, Junnan Hu, Bolong Huang, Mingzi Sun, Bowei Dong, G. Zheng, Yuan Huang, Yihua Chen, Liang Li and 6 more. Science, 2019

821 citations recorded by the source corpus.

A redox road to recovery Device longevity is a key issue for organic-inorganic perovskite solar cells. Encapsulation can limit degradation arising from reactions with oxygen and water, but light, electric-field, and thermal stresses can lead to metastable elemental lead and halide atom defects. Wang et al. show that for the lead-iodine system, the introduction of the rare earth europium ion pair Eu3+-Eu2+ can shuttle electrons and recover lead and iodine ions (Pb2+ and I−). Devices incorporating this redox shuttle maintained more than 90% of their initial power conversion efficiencies under various aging conditions. Science, this issue p. 265 A rare earth redox couple restores neutral lead and iodine defects to their ionic state. The components with soft nature in the metal halide perovskite absorber usually generate lead (Pb)0 and iodine (I)0 defects during device fabrication and operation. These defects serve as not only recombination centers to deteriorate device efficiency but also degradation initiators to hamper device lifetimes. We show that the europium ion pair Eu3+-Eu2+ acts as the “redox shuttle” that selectively oxidized Pb0 and reduced I0 defects simultaneously in a cyclical transition. The resultant device achieves a power conversion efficiency (PCE) of 21.52% (certified 20.52%) with substantially improved long-term durability. The devices retained 92% and 89% of the peak PCE under 1-sun continuous illumination or heating at 85°C for 1500 hours and 91% of the original stable PCE after maximum power point tracking for 500 hours, respectively.

Subfields: Electrical and Electronic Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/d8b3593d5c1eb6d5065cad1a96570500a2a586f7