Untying the Cesium "Not": Cesium-Iodoplumbate Complexation in Perovskite Solution-Processing Inks Has Implications...

Area of Science:

• Materials Science
• Solid-State Chemistry
• Physical Chemistry

Background:

• The stability of ABX3 perovskite precursors is crucial for efficient device fabrication.
• Understanding cation-solvent and cation-iodoplumbate interactions is key to controlling precursor stability.

Purpose of the Study:

• To investigate the distinct interactions of Cs+ versus organic cations (like MA+) with iodoplumbate in DMF.
• To elucidate the role of cation energetics in determining perovskite precursor stability.

Main Methods:

• Complementary nuclear magnetic resonance (NMR) spectroscopy (133Cs and 207Pb) was employed.
• Computational studies including density functional theory (DFT), ab initio molecular dynamics (AIMD), and polarizable force field molecular dynamics were utilized.

Main Results:

• NMR studies revealed that Cs+ and MA+ compete for PbI3- coordination in DMF.
• 207Pb NMR indicated anomalous chemical shifts for Cs+ and Rb+ compared to alkali metal cations.
• Computational methods consistently showed stronger Cs+-PbI3- interactions than MA+-PbI3- interactions in DMF.

Conclusions:

• Cs+ exhibits a stronger energetic preference for iodoplumbate coordination than MA+ in DMF.
• This stronger interaction suggests Cs+ actively participates in precursor preorganization, not just post-crystallization fitting.