OverView

JALS is a system which measures angle-dependent PL and EL emission intensities and analyzes the orientation and position of excitons in thin films or LEDs such as PLEDs, QDLEDs, or perovskite LEDs. Both PL and EL emission intensity measurement functionalities are included in this compact instrument and the alignment of optics can be done very easily. This measurement system is coupled to the JALS simulation software for data analysis or more powerful simulation software J-OSTD for parameter extraction and device modeling. Additionally, refractive index database is included in the software for various materials.

PL and EL excitation: Emitter orientation and position 

Angular PL intensity measured by JALS to get the emitter orientation using the JALS simulation Software. P-and s- polarization angular emission intensities can be measured.

Angular EL spectra (symbols) measured by JALS are compared with the simulation results (lines) performed using the extracted emitter position. (below left figure)

Exciton density profile extracted from angular EL spectra of an OLED using J-OSTD.

Comparison of the Angular p-pol EL spectra (symbols) measured by JALS with the simulation results (lines) performed by J-OSTD.

Operation Modes

● Color Efficiency
● Viewing angle
● Efficiency: (EQE, Lm/W and Cd/A)
● Orientation & position of the Emitting dipoles or emitters

● Emittter Orientation
● Spectrum and color per emission angle
● Polarized emission

Data Analysis

● Efficiency
● CIE coordinates
● Color temperature, CRI

● Spectral intensity
● Luminous intensity

References

Origin and Control of Orientation of Phosphorescent and TADF Dyes for High-Efficiency OLEDs
Kwon-Hyeon Kim and Jang-Joo Kim*
Adv. Mater. 2018, 30, 1705600

https://onlinelibrary.wiley.com/doi/full/10.1002/adma.201705600
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It has been known for decades that the emitting dipole orientation (EDO) of emitting dyes influences the outcoupling efficiency of organic light-emitting diodes (OLEDs). However, the EDO of dopants, especially phosphorescent dopants, has been studied less than that of neat films and polymer emitting layers (EMLs) due to the lack of an apparent driving force for aligning the dopants in amorphous host films. Recently, however, even globular-shaped Ir complexes have been reported to have a preferred orientation in doped films and OLEDs. External quantum efficiencies (EQEs) higher than 30% have also been demonstrated using phosphorescent and thermally activated delayed fluorescent dyes (TADF) doped in EMLs. Here, recent results on the EDO of phosphorescent and TADF dyes doped in host films, and highly efficient OLEDs using these dyes are reviewed. The origin and control of the orientation of phosphors are discussed, followed by a discussion of future strategies to achieve EQEs of over 60% without a light extraction layer, from the material point of view.