Ultrathin PEDOT:PSS Enables Colorful and Efficient Perovskite Light-Emitting Diodes

Area of Science:

• Materials Science
• Optoelectronics
• Nanoscience

Background:

• Metal halide perovskite light-emitting diodes (Pero-LEDs) show promise for advanced lighting and display technologies.
• External quantum efficiency (EQE) is a critical metric for Pero-LED performance, influenced by internal quantum efficiency, charge injection balancing (ηc), and light extraction efficiency (LEE).

Purpose of the Study:

• To develop an ultrathin hole transporter layer to simultaneously enhance charge injection balancing and light extraction efficiency in Pero-LEDs.
• To investigate the universal applicability of the developed layer across different perovskite architectures (3D, quasi-3D, quasi-2D).

Main Methods:

• Fabrication of an ultrathin poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (UT-PEDOT:PSS) layer using a water stripping method.
• Integration of the UT-PEDOT:PSS layer as a hole transporter in various Pero-LED devices.
• Characterization of device performance, focusing on EQE, ηc, and LEE.

Main Results:

• The UT-PEDOT:PSS layer improved carrier mobility, energy level alignment, and reduced photon loss, thereby enhancing both ηc and LEE.
• Pero-LEDs incorporating UT-PEDOT:PSS demonstrated significant EQE enhancements: 42% for 3D, 87% for quasi-3D, and 111% for quasi-2D perovskites.
• Maximum EQEs reached 17.6% (3D), 15.0% (quasi-3D), and 6.8% (quasi-2D) perovskites, showcasing the layer's effectiveness.

Conclusions:

• The UT-PEDOT:PSS layer is a highly effective and universally applicable component for significantly boosting Pero-LED performance.
• This approach offers a viable strategy for advancing the efficiency of next-generation perovskite optoelectronic devices.