Significant lifetime enhancement, up to an eight-fold
increase
in T90, has been demonstrated in blue organic light-emitting
diode (OLED) devices through the deuteration of host and hole transport
materials. We observed a progressive increase in T90 using
a series of anthracene-based hydrocarbon hosts with incremental deuteration
in the emitting layer. In addition, we realized further lifetime improvement
using a deuterated hole-transport layer along with the deuterated
emitting layer. To elucidate the deuteration effects, we utilized
laser desorption/ionization-time-of-flight (LDI-TOF) mass spectrometry
for in situ UV irradiation to induce photodegradation and immediate
chemical analysis of the resultant photodegradation species. Adducts
between the host and moieties from transport materials were identified
in UV-degraded films comprising a mixture of host and transport materials,
indicating that similar species could be produced in OLED devices
using these materials. Deuteration, in effect, mediated the formation
of these adduct species, presumably electroluminescence quenchers,
and thus improved the device lifetime. An approximate agreement was
obtained between the kinetic isotope effect of the photodegradation
reactions and the enhancement in device lifetime with deuteration.
We developed a 2‐inch, 2000 ppi shadow mask based on micronthin, free‐standing silicon nitride (SiNx) membrane for patterning OLED displays. Its layer composition and fabrication process were optimized to yield an ultra‐flat, self‐tensioned silicon nitride mask (SNM) that can achieve a submicron shadow distance limited only by the thickness of the membrane in line‐of‐sight vacuum depositions.
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