Ethylamine Iodide Additive Enables Solid-to-Solid Transformed Highly Oriented Perovskite for Excellent Photodetectors

Area of Science:

• Materials Science
• Solid-State Chemistry
• Optoelectronics

Background:

• Perovskite materials are vital in optoelectronics due to excellent light absorption and carrier mobility.
• High crystallization is essential for high-performance perovskite devices.
• The working mechanisms of additives used to improve perovskite crystallization are not well understood.

Purpose of the Study:

• To introduce ethylamine iodide (EAI) as an additive for fabricating highly crystalline formamidinium-lead triiodide (FAPbI3) perovskite films.
• To elucidate the novel working mechanism of alkyl amine additives in perovskite crystallization.
• To demonstrate the performance of perovskite films fabricated using this method.

Main Methods:

• Introduction of ethylamine iodide (EAI) into perovskite precursor solutions.
• Investigation of the crystallization process using a proposed solid-to-solid (S-S) transition mechanism.
• Fabrication and characterization of a self-powered photodetector.

Main Results:

• A new method using EAI successfully produced highly crystalline FAPbI3 perovskite films.
• The study revealed that EAI influences the solid-to-solid (S-S) transition from the yellow to the black phase, differing from traditional liquid-to-solid (L-S) theory.
• This S-S transition mechanism was confirmed to be applicable to other common alkyl amines.
• A self-powered photodetector achieved an external quantum efficiency exceeding 90%.

Conclusions:

• Ethylamine iodide (EAI) effectively promotes the formation of highly crystalline FAPbI3 perovskite films.
• The findings propose a novel solid-to-solid (S-S) crystallization mechanism for alkyl amine additives in perovskites.
• This research deepens the understanding of perovskite crystallization and its impact on device performance.