Computational Analysis of the Interplay between Deep Level Traps and Perovskite Solar Cell Efficiency

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Physics

Background:

• Halide perovskite solar cells offer high power conversion efficiency.
• Methylammonium lead iodide (MAPbI₃) is a key perovskite material.
• Deep level traps in MAPbI₃ limit solar cell performance by promoting charge carrier recombination.

Purpose of the Study:

• To investigate the influence of deposition methods on the spatial distribution of deep level traps in MAPbI₃ solar cells.
• To elucidate the relationship between trap distribution and solar cell efficiency.
• To understand the origin of efficiency differences between one-step and two-step processing methods.

Main Methods:

• Finite-element drift-diffusion modeling to simulate photoexcited charge carrier pathways.
• Analysis of one-step and two-step processed MAPbI₃ solar cells.
• Composition and structural analysis of perovskite films.

Main Results:

• One-step processing results in deep level traps distributed throughout the bulk MAPbI₃ film.
• Two-step processing leads to the congregation of deep level traps at the MAPbI₃/mesoporous TiO₂ interface.
• Significant differences in solar cell efficiency (13.5% for one-step vs. 17.7% for two-step) correlate with trap distribution.

Conclusions:

• The spatial distribution of deep level traps is critically dependent on the perovskite deposition method.
• Interface-localized traps in two-step processed cells are less detrimental to efficiency than bulk-distributed traps in one-step processed cells.
• Understanding and controlling trap distribution is essential for optimizing perovskite solar cell performance.