Efficient electron injection layer based on thermo-cleavable materials for inverted bottom-emission polymer light emitting diodes

摘要

The electron injection material PF-EP was found to be thermo-cleavable. Its solubility in chlorobenzene can be adjusted by thermal treatment at different temperatures. By analyzing the results of TGA, FT-IR, and ~(13)C solid-state NMR, we interpret that the solubility transition is caused by partial acidification, crosslinking through a hydrogen-bonded network and coordination of O, P and Li. Based on this thermo-cleavable approach, efficient fully solution-processed IBPLEDs were successfully fabricated. The maximum current efficiency of the device with 2.5% Li2CO3 doped PF-EP as the EIL reaches nearly 1.7 times of that of a conventional device. We attribute the high performance to the good electron injection and hole blocking abilities of PF-EP and Li2CO3.