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Two-Step Crystallization for Low-Oxidation Tin-Based Perovskite Light-Emitting Diodes.
Yu-Hong Cheng1, Reine Moriyama1, Hinako Ebe1
1Graduate School of Organic Materials Science, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan.
ACS Applied Materials & Interfaces
|January 25, 2022
Summary
Researchers developed a two-step crystallization method for lead-free PEA2SnI4 perovskites. This process reduces harmful Sn4+ oxidation, improving red emission properties and enhancing device performance for eco-friendly optoelectronics.
Area of Science:
- Materials Science
- Optoelectronics
- Solid-State Chemistry
Background:
- Metal halide perovskites are highly regarded for their optoelectronic properties.
- Lead toxicity in traditional perovskites raises environmental concerns.
- PEA2SnI4 offers a lead-free alternative with pure red emission, but is prone to Sn4+ oxidation.
Purpose of the Study:
- To develop a method to stabilize PEA2SnI4 perovskites against Sn4+ oxidation.
- To improve the optoelectronic properties and device performance of lead-free perovskites.
- To demonstrate a generalizable synthesis approach for lead-free materials.
Main Methods:
- Two-step crystallization involving reprecipitation and recrystallization.
- Fabrication of PEA2SnI4 films and devices.
- Characterization using photoluminescence spectroscopy and diffusion-ordered spectroscopy.
- Performance evaluation of light-emitting diodes (LEDs).
Main Results:
- The two-step crystallization significantly reduced Sn4+ content by five times compared to control films.
- Films exhibited narrowed emission (FWHM from 30.0 to 26.1 nm) due to homogeneous emission.
- PEA2SnI4-based LEDs showed a two-fold increase in external quantum efficiency (EQE), reaching 0.4% maximum.
Conclusions:
- The two-step crystallization method effectively suppresses Sn4+ oxidation in PEA2SnI4 perovskites.
- This approach enhances emission properties and LED performance, paving the way for stable, lead-free optoelectronic devices.
- The demonstrated method holds potential for synthesizing other lead-free perovskite materials.
