Dendritic CsSnI₃ for Efficient and Flexible Near-Infrared Perovskite Light-Emitting Diodes

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• All-inorganic and lead-free CsSnI3 is a promising material for near-infrared perovskite light-emitting diodes (NIR Pero-LEDs).
• Existing CsSnI3 Pero-LEDs suffer from unbalanced charge injection, with higher hole injection than electron injection, leading to poor device performance.
• Applications for NIR Pero-LEDs include facial recognition, biomedical devices, and night vision cameras.

Purpose of the Study:

• To manage charge injection and recombination behavior in CsSnI3 Pero-LEDs by tuning the interface area between the perovskite and charge-transport layers.
• To improve the efficiency and stability of lead-free NIR Pero-LEDs.

Main Methods:

• A dendritic CsSnI3 structure was prepared on a hole-transporter layer.
• The dendritic structure ensured only bottom contact with the hole-transporter, exposing other crystal surfaces to the electron-transporter.
• This configuration significantly increased the interface area between the perovskite and electron-transporter compared to the perovskite/hole-transporter interface.
• The embedded interface spatially confined holes and electrons, enhancing radiative recombination.

Main Results:

• The dendritic structure led to efficient lead-free NIR Pero-LEDs with a record external quantum efficiency (EQE) of 5.4%.
• The devices demonstrated excellent flexibility, with minimal morphological change after 2000 bending cycles.
• Fabricated Pero-LEDs retained 93.4% of their initial EQE after 50 bending cycles.

Conclusions:

• Tuning the interface area using a dendritic CsSnI3 structure effectively manages charge injection and recombination.
• This approach significantly enhances the performance of lead-free NIR Pero-LEDs.
• The dendritic structure offers superior stability and flexibility for advanced optoelectronic applications.