A systematic approach to reducing angular color shift in cavity-based organic light-emitting diodes

Abstract The white angular dependence (WAD) is considered a serious problem in top emitting OLEDs (TOLEDs), both in monochrome and multi-color subpixel configurations. This work aims at providing a systematic strategy for obtaining WAD-free performance with little compromise in efficiency in TOLED-based multi-color displays. Starting with a slightly blue-detuned microcavity structure leading to low WAD per individual primary colors, we try to look for a condition where angular intensity drop rates are well balanced among the subpixels involved and yet the efficiency can be maintained within a certain threshold value. With the proposed protocol, red, green and blue TOLEDs are demonstrated that show a very low angular color shift of 2.4 “just noticeable color difference” (JNCD), 1.7 JNCD, and 1.4 JNCD for red, green, and blue devices themselves and 1.4 JNCD for a 1:1:1 mixture of red, green and blue. These devices are shown to exhibit not only low WAD but also high efficiency that is still within 70% of the maximum achievable values.