2, Pohang University of Science and Technology, Pohang, , Korea (the Republic of)
The electroluminescence efficiency of metal halide perovskite light-emitting diodes (PeLEDs) has been rapidly increased during recent years. Conducting polymer anodes (CPAs) have been very effective to realize high efficiency in simplified PeLEDs. An ideal CPA requires high conductivity, high work function WF, and prevention of exciton quenching between an anode and an overlying metal halide perovskite layer. However, increasing the conductivity and WF at the same time has been very challenging because chemical or molecular approaches to increase the WF have reduced the films’ conductivity. Chemical post-treatment on CPA films to increase the conductivity is not suitable for mass production of the reliable CPA. Here, we introduce a chemical additive approach without chemical post-treatment, to simultaneously increase conductivity and WF of CPAs. The CPA composition includes a WF-tuning fluoropolymer, but the chemical additives affect only the PEDOT:PSS conducting polymer. The additives weaken the coulombic interaction between positively-charged PEDOT and negatively-charged PSS, and thereby improve the interaction of conducting PEDOT chains. This change resulted in a record current efficiency up to 52.86 cd A-1 (10.93 % ph el-1) in green PeLEDs. Our results provide a significant clue to develop effective CPAs for highly-efficient PeLEDs.