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/m² under the current density 20 mA/cm² of this tandem organic light emitting device (TOLED) are yielded, which are notably almost the sum of that of the two single-unit devices.