Calibrating the Hole Mobility Measurements Implemented by Transient Electroluminescence Technology

Area of Science:

• Materials Science
• Organic Electronics
• Spectroscopy

Background:

• Measuring carrier mobility in amorphous organic small-molecule films presents significant challenges.
• Existing methods often lack precision for these complex materials.

Purpose of the Study:

• To establish a feasible and reliable method for evaluating carrier mobility in amorphous organic films.
• To utilize transient electroluminescence (TrEL) spectroscopy with quantum-dot light-emitting diodes (QLEDs) as a platform.

Main Methods:

• Employing a quantum dot monolayer as the emissive layer to precisely control exciton formation zone.
• Calculating charge density at the electrode via transient current to determine electrical field intensity.
• Obtaining charge carrier mobility by combining electroluminescence (EL) delay time and organic layer thickness.

Main Results:

• Demonstrated TrEL spectroscopy as a viable technique for amorphous organic film characterization.
• Identified that large organic layer roughness causes charge accumulation, localized electrical fields, and underestimates mobility.
• Established that a thick organic film is crucial for accurate carrier mobility measurements, mitigating roughness effects.

Conclusions:

• Transient electroluminescence spectroscopy with QLEDs provides a robust method for assessing carrier mobility in amorphous organic films.
• Film thickness is a critical parameter to ensure reliable measurements by overcoming surface roughness issues.