Minimizing and Controlling Hydrogen for Highly Efficient Formamidinium Lead Triiodide Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Physics

Background:

• Formamidinium lead triiodide (FAPbI3) is a leading material for single-junction perovskite solar cells, achieving record efficiencies.
• Iodine management is crucial for reducing nonradiative losses in FAPbI3, but the exact mechanisms remain unclear.
• Understanding nonradiative loss origins is key to further improving perovskite solar cell performance.

Purpose of the Study:

• To identify the primary cause of nonradiative losses in FAPbI3 perovskite solar cells.
• To elucidate the mechanism by which iodine concentration influences these losses.
• To provide insights for optimizing FAPbI3 material for high-efficiency solar devices.

Main Methods:

• Utilized first-principles simulations to investigate defect properties and their impact on electronic states.
• Analyzed the role of native point defects and interstitial species under varying iodine concentrations.
• Modeled the behavior of hydrogen species (ions and molecules) within the FAPbI3 lattice.

Main Results:

• Native point defects were found not to be the dominant source of nonradiative losses in FAPbI3.
• Hydrogen ions were identified as efficient nonradiative recombination centers, significantly reducing power conversion efficiency.
• Iodine-moderate synthesis conditions promote the formation of inactive molecular hydrogen, suppressing harmful hydrogen ions.

Conclusions:

• Hydrogen ions are the dominant nonradiative recombination centers in FAPbI3 perovskite layers.
• Iodine management strategies effectively reduce nonradiative losses by mitigating hydrogen ion concentration.
• Minimizing unintentional hydrogen incorporation is critical for achieving optimal device performance in FAPbI3 solar cells.