In recently developed organic semiconductors,
the continuously
improving sample purity makes the stability of the chemical bonds
of organic materials themselves become a key factor in device stability,
which provides greater uncertainty for the generation of “zeroth
defect”, and the spatial resolution of performance at different
positions becomes particularly important. In this work, complete maps
of electroluminescent, photoluminescent, and Raman scattering in the
same area on an organic light-emitting diode during its operation
have been achieved with a confocal spectrometer with multiple laser
sources. The different spectral characters help to establish different
regions and suggest the mechanism of degradation. In particular, Raman
scattering has been shown to be very sensitive in a multilayer device
to a change in thickness of several nanometers. In amorphous films
with few defects, the very weak film uniformity, including the thickness
and degree of aggregation, would induce dramatic degradation. The
relatively thin and/or loosely textured region easily locally overheats
and has the highest probability of “zeroth defect” generation.
This method has high spatial resolution, a low level of damage to
samples, good reproducibility, and multiple interconnected pieces
of information, which is significant for online quality prediction
and mechanistic analysis.