The operating voltage behavior of green fluorescent organic light emitting diode with blue common layer structure during laser imaging process

The blue common layer (BCL) approach has become very useful methodology to reduce the process steps which may increase the production yield of active matrix organic light emitting diode (AMOLED) fabrication. From this approach, we can reduce one step (from 5 to 4) for fine metal masking (FMM) method as a current mass-production technology to form a common thick-microcavity structure. Moreover, we can reduce the patterning steps from 5 to 2 if we use a laser induced thermal imaging (LITI) technology for the same structure. Nevertheless, we still prefer to apply the FMM technology for the mass production because there are lots of problematic issues on LITI process such as an operating voltage increase (by 0.5-1.0 V), efficiency drop (by ∼10%), shorter lifetime, etc. Here, we report about the fundamental causes of these problems during LITI processes.