Highly Efficient Inverted Light-Emitting Diodes Based on Vertically Aligned CdSe/CdS Nanorod Layers Fabricated by...

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Colloidal-nanocrystal-based LEDs (NC-LEDs) are promising for displays and flexible electronics.
• Semiconductor nanorods (NRs) offer advantages over quantum dots (QDs), including tunable emission and improved stability.
• Achieving void-free NR layers with traditional methods like spin-coating is challenging.

Purpose of the Study:

• To develop a method for fabricating closely packed, vertically aligned CdSe/CdS core/shell nanorod layers for NC-LEDs.
• To investigate the performance of NC-LEDs utilizing these vertically aligned NR layers.
• To demonstrate the effectiveness of electrophoretic deposition (EPD) for creating ordered nanorod structures.

Main Methods:

• Electrophoretic deposition (EPD) was used to create closely packed, vertically aligned CdSe/CdS core/shell nanorods.
• An inverted device architecture was employed for the NC-LED fabrication.
• Finite element simulations were used to analyze charge transport properties.

Main Results:

• The fabricated inverted NC-LEDs achieved an external quantum efficiency (EQE) of 6.3% and a maximum luminance of 4320 cd/m² at 11 V.
• Vertically aligned NR layers significantly enhanced charge transport by reducing carrier passage resistance.
• This work reports the first use of EPD for vertically aligned NR layers in NC-LEDs, achieving top-tier performance for red NR-LEDs.

Conclusions:

• EPD is a simple and effective technique for producing vertically aligned nanorod layers for optoelectronic devices.
• The enhanced performance of the NC-LEDs is attributed to the improved charge transport facilitated by the aligned NR structure.
• This method holds potential for advancing various nanocrystal-based optoelectronics, including solar cells and lasers.