High-energy-level blue phosphor for solution-processed white organic light-emitting diodes with efficiency comparable to fluorescent tubes

Abstract

A high-energy-level blue phosphor Flr-p-OC8 has been developed for solution-processed white organic light-emitting diodes (WOLEDs) with comparable fluorescent tube efficiency. Benefiting from the electron-donating nature of the introduced alkoxy, Flr-p-OC8 shows not only efficient blue light but also elevated highest occupied molecular orbital/lowest unoccupied molecular orbital levels to well match the dendritic host H2. Consequently, the hole scattering between Flr-p-OC8 and H2 can be prevented to favor the direct exciton formation on the blue phosphor, leading to reduced driving voltage and thus improved power efficiency. By exploiting this approach, a maximum power efficiency of 68.5 lm W-1 is achieved for Flr-p-OC(8-)based white devices, slightly declining to 47.0 lm W-1 at a practical luminance of 1,000 cd m(-2). This efficiency can be further raised to 96.3 lm W-1 @ 1,000 cd m(-2) when a half-sphere is applied to increase light out-coupling. We believe that our results can compete with commercial fluorescent tubes, representing an important progress in solution-processed WOLEDs.