Efficient perovskite light-emitting diodes on a flexible substrate.

Area of Science:

• Materials Science
• Optoelectronics
• Film Deposition

Background:

• Substrate surface properties critically influence metal halide perovskite film growth via anti-solvent methods.
• Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is a common substrate, but its acidic surface can impede perovskite quality.

Purpose of the Study:

• To improve the quality of quasi-2D perovskite films using a modified substrate.
• To investigate the effect of a branched polyethylenimine (PEI) layer on perovskite film properties and device performance.

Main Methods:

• Fabrication of quasi-2D perovskite films on PEDOT:PSS substrates modified with a PEI layer.
• Characterization of perovskite film phases, defects, photoluminescence quantum efficiency, and photoluminescence lifetime.
• Fabrication and performance testing of flexible perovskite light-emitting diodes (PeLEDs).

Main Results:

• The PEI layer neutralized the acidic PEDOT:PSS surface, promoting larger-n phase formation in perovskite films.
• PEI modification reduced film defects, leading to higher photoluminescence quantum efficiency and longer photoluminescence lifetime.
• Flexible PeLEDs fabricated on PEI-modified substrates achieved a current efficiency of 63.2 cd/A, nearly double that of devices without PEI (35.1 cd/A).

Conclusions:

• Branched PEI is an effective surface modifier for PEDOT:PSS substrates in perovskite film fabrication.
• PEI-modified substrates yield high-quality perovskite films with enhanced optoelectronic properties.
• This approach significantly improves the performance of flexible perovskite light-emitting diodes.