Structural Isomer of Fluorinated Ruddlesden-Popper Perovskites Toward Efficient and Stable 2D/3D Perovskite Solar...

Area of Science:

• Materials Science
• Photovoltaics
• Chemical Engineering

Background:

• Two-dimensional (2D) layered perovskites are used to passivate defects in 3D bulk perovskite solar cells, enhancing stability and efficiency.
• Fluorination of organic spacers in 2D perovskites imparts hydrophobicity and improves defect passivation.

Purpose of the Study:

• To investigate how conformational changes of fluorine isomers in 2D perovskite spacers affect opto-electrical properties.
• To explore the potential of meta- and para-trifluoromethyl (CF3) groups on phenethylammonium iodide (PEAI) spacers as interfacial modifiers in perovskite solar cells.

Main Methods:

• Synthesis of 2D perovskites using meta-CF3-PEAI and para-CF3-PEAI spacers.
• Fabrication and characterization of 2D/3D perovskite solar cell heterostructures.
• Experimental analysis of charge transport, trap state suppression, and energy alignment.
• Theoretical simulations to validate experimental findings.

Main Results:

• Different fluorination positions (meta- vs. para-CF3) on PEAI spacers lead to distinct opto-electrical characteristics in 2D perovskites.
• The meta-CF3-PEAI based 2D perovskite enhanced out-of-plane charge transport and suppressed trap states in the 3D perovskite absorber.
• Altered intermolecular interactions and interlayer spacing due to fluorination isomerism influenced the properties of the 2D/3D heterostructures.
• Experimental results were corroborated by theoretical simulations.

Conclusions:

• Structural isomers of fluorination on spacer cations offer a tunable strategy to control perovskite solar cell performance.
• The meta-CF3-PEAI spacer demonstrated superior performance, indicating its potential for improving both efficiency and stability in 2D/3D perovskite solar cells.
• Controlling spacer conformation and interlayer spacing is crucial for optimizing perovskite solar cell devices.