Cation Engineering by Three-Dimensional Organic Spacer Cations for Effective Defect Passivation in Perovskite Solar Cells

Graphical A new three-dimensional organic spacer cation, 1,4-diazabicyclo [2,2,2] octane-1,4-diium (DABCO 2+ ) was developed to passivate defects and enhance the device stability. Low-dimensional additive engineering could effectively reduce the high-density trap defect density and improve the stability of perovskite solar cells (PSCs). To avoid the limiting effect of charge carrier transfer by incorporating the large-size long alkyl chain organic cations, we developed a new three-dimensional organic spacer cation, 1,4-diazabicyclo [2,2,2] octane-1,4-diium (DABCO 2+ ), to passivate the defects and enhance the device stability. DABCO 2+ with fine crystal structure and thermal stability could result in substantially fewer structural defects, enhance carrier lifetime, and inhibit nonradiative recombination loss. Structural analysis of CsFAPbI 3 perovskite doped with different concentrations of the three-dimensional organic spacer cations shows a clear correlation between the structure and the resultant perovskite films. Consequently, DABCO 2+ modified CsFAPbI 3 -based PSCs could achieve an optimized PCE of 23.02% with high stability exceeding 1500 h. This work opens a new approach to fabricating PSCs with enhanced stability for future commercial applications.