Mixed-Cation Engineering for Orientation Control and Defect Suppression in Quasi-2D Dion-Jacobson-Type Tin...

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Chemistry

Background:

• Low-n-member quasi-two-dimensional (quasi-2D) tin (Sn) perovskites, especially Dion-Jacobson (DJ) phase materials, offer stability and a lead-free alternative for solar cells.
• Key limitations include poor out-of-plane crystallographic orientation and high defect densities, impeding charge transport and device performance.

Purpose of the Study:

• To overcome orientation and defect limitations in low-n quasi-2D Sn perovskites.
• To enhance the performance of lead-free perovskite solar cells through mixed-cation engineering.

Main Methods:

• Employed a mixed-cation engineering strategy using N,N-dimethyl-p-phenylenediammonium (DMPhDA²⁺) and phenylethylammonium (PEA⁺) spacers.
• Utilized PEA⁺ as an orientation-directing spacer to reduce steric hindrance and promote vertical growth.
• Investigated the modulation of crystallization, defect suppression, and Sn²⁺ oxidation states.

Main Results:

• Achieved enhanced vertical crystallographic orientation and improved alignment within the perovskite structure.
• Successfully suppressed structural defects and prevented Sn²⁺ oxidation.
• Optimized low-n quasi-2D DJ/RP perovskite solar cells reached a power conversion efficiency (PCE) of 6.76%.

Conclusions:

• The mixed-cation approach effectively addresses orientation and defect issues in low-n Sn-based perovskites.
• This strategy provides a viable pathway for developing stable and efficient lead-free perovskite solar cells.
• Advances the field of perovskite photovoltaics towards practical, environmentally friendly applications.