Dipole orientation analysis without optical simulation: application to thermally activated delayed fluorescence...

Area of Science:

• Materials Science
• Optoelectronics
• Physical Chemistry

Background:

• Investigating guest emitter dipole orientation in host matrices typically relies on angular dependent photoluminescence (PL) measurements.
• Analysis of PL radiation patterns often necessitates complex optical simulations, requiring specialized expertise.
• Existing methods for determining dipole orientation are computationally intensive and difficult to interpret.

Purpose of the Study:

• To develop a simplified method for calculating the orientational order parameter (S) of guest emitters in thin films.
• To eliminate the need for complex optical simulations in analyzing PL radiation patterns.
• To establish a direct correlation between peak photoluminescence intensity (I_sp) and the orientational order parameter (S).

Main Methods:

• Developed a novel method to calculate the orientational order parameter (S) without full optical simulations.
• Analyzed the relationship between peak photoluminescence intensity (I_sp) and S, considering film thickness (d) and refractive indices (n_sub, n_org).
• Applied the method to thermally activated delayed fluorescence (TADF) materials.

Main Results:

• A direct correlation was established between I_sp and S, simplifying the determination of dipole orientation.
• The S-I_sp relationship was found to be dependent on film thickness and refractive indices.
• The developed method demonstrated high accuracy, with errors less than 0.05 compared to optical simulations for TADF materials.

Conclusions:

• The new method provides a straightforward approach to calculate the orientational order parameter (S) using readily available experimental data (I_sp, d, n_sub, n_org).
• This technique significantly reduces the complexity and expertise required for analyzing dipole orientation in guest-host thin films.
• The method is effective for efficient electroluminescence emitters like TADF materials, facilitating materials characterization in optoelectronics.