Efficient blue fluorescence tandem organic light emitting device with a novel intermediate connector

A novel intermediate connector(IC) was formed which was composed of aluminum(Al, 3 nm)/1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile(HAT-CN).The 3-nm-thick Al in the IC is certified to efficiently generate intrinsic charge carriers, and the HAT-CN is proved to work as the holes injection layer(HIL) for the corresponding electroluminescent(EL) unit simultaneously.This simply IC comprehensively takes advantage of the features of the HAT-CN so as to stack two single EL units without introducing extra material.In addition to a significant enhancement in luminance and current efficiency, a current efficiency(CE) of 10.2 cd/A and a luminance of 2 042 cd/m^2 under the current density 20 mA/cm^2 of this tandem organic light emitting device(TOLED) are yielded, which are notably almost the sum of that of the two single-unit devices.