Fabrication of color conversion layers using adhesive transfer of phosphor particles for improving light extraction efficiency and uniformity of down-conversion white OLED

The down-conversion white OLED is one of the simple and effective ways for OLED display and lighting; it consists of a color conversion layer (CCL) and a blue-emitting source of the OLED. This paper introduces a process for adhesive transfer (AT) of phosphor particles to improve the light extraction efficiency and uniformity. The CCL formed by AT shows a surface fill factor of 91.6%, and is 5.5 times thinner than the one formed by wet-casting. In particular, the CCL fabricated by AT on a blue OLED achieved a 166% higher luminous efficiency than the wet-cast CCL. The effect of an extra non-emitting particle layer on top of the CCL fabricated by AT was also investigated and significant improvement was observed in both areal and angular uniformities (up to 99%). This transfer process for fabricating the CCLs is expected to play an important role in producing OLED displays and lighting with high efficiency at low cost.