Researchers from China's Tianjin University of Technology, Zhejiang Sci-Tech University, University of Electronic Science and Technology of China, North China Electric Power University and South China University of Technology have shown that the introduction of azetidinium iodide (AZI) into the precursor solution of a 1.77 eV bandgap FA0.8Cs0.2Pb(I0.6Br0.4)3 perovskite significantly improves the efficiency and stability of the perovskite cells.
Devices fabricated with 2 mol% AZI (relative to FAI, noted as AZ2) in perovskite layer exhibited a high PCE of 19.16 % and a high open-circuit voltage of 1.31 V. When stored under nitrogen atmosphere and illuminated under 1 sun conditions for 300 h, AZ2 device retained 80 % of the initial values.
After heating at 60 °C for 200 h under a nitrogen atmosphere, the PCE of the AZ2 device maintained 77 % of the initial values. When kept in an ambient environment with 60 % RH and a temperature of 30°C for 650 h, the AZ2 device retained 78 % of the initial values.
The team's strategy manages to enhance the efficiency and stability of wide-bandgap perovskite solar cells. The AZI can not only stabilize I- through hydrogen bonding, preventing the generation of I2 and I3-, but can also passivate Pb-related defects and cation vacancy defects, thereby reducing the defect density and improving the quality of the perovskite films. The introduction of AZI suppresses light-induced phase separation and increases moisture, thermal, and light stability.
