On the origin of the shift in color in white organic light-emitting diodes

White organic light-emitting diodes (WOLEDs) have attracted more and more attention in recent years because of their potential applications on flat-panel displays, solid-state lighting, and liquid-crystal display backlighting sources. With the goal towards practical applications, it requires WOLEDs possess not only high brightness and large electroluminescent (EL) efficiency, but also excellent stability. Here, good device stability includes two aspects, these are long operation lifetime and good color stability over a wide EL range. In this review, we explored all possible factors rendering a shift in color in both single- and multiple-emitting layer WOLEDs and summarized some typical design strategies for preventing shift in color of white emission. We hope the present paper can provide valuable clues to academic researchers and industrial designers in developing highly efficient WOLEDs with extremely stable chromaticity.