# Perspective: OLED Displays Singing with the Blues

## TL;DR

This paper discusses the progress and remaining challenges in developing stable blue phosphorescent OLEDs for energy-efficient displays.

## Contribution

The paper highlights recent advancements in achieving stable deep blue OLEDs and outlines remaining technical hurdles.

## Key findings

- Deep blue PHOLEDs now approach the lifetimes of green PHOLEDs through improved design and outcoupling techniques.
- Triplet-controlled emitters remain a focus for further development to meet display industry standards.
- Persistent issues in measuring quantum efficiency and operational lifetime are identified in the literature.

## Abstract

While blue pixels consume approximately 50% of the energy of organic light‐emitting diode (OLED) display front planes, in the 25 years since their invention, 100% internal efficiency phosphorescent OLEDs (PHOLEDs) have not met the stability standards necessary for their adoption. In this perspective, we discuss the significant progress and challenges encountered during this long journey of exploration and discovery. Today, using a combination of solutions including robust molecular design, graded doping of the emission layer, increasing the optical density of states to decrease the triplet radiative lifetime, and employing light outcoupling schemes, deep blue PHOLEDs are now achieving lifetimes approaching those of their green analogs. This perspective elaborates on the challenges and opportunities confronting further development of triplet‐controlled emitters, including PHOLEDs using heavy‐metal phosphors and thermally activated delayed fluorescent OLEDs. We also address some persistent problems commonly found in the literature concerning the measurement of quantum efficiency and operational lifetime.

While blue pixels consume approximately 50% of the energy of OLED display front planes, in the 25 years since their invention, 100% internal efficiency triplet‐controlled phosphorescent OLEDs have not met the stability standards necessary for their adoption. In this perspective, we discuss the progress and challenges encountered during this long journey of exploration and discovery. Using a combination of strategies, these devices are nearly ready to meet the most stringent demands of the highest quality mobile displays and televisions.