Characterization of Ion Profiles in Light-Emitting Electrochemical Cells by Secondary Ion Mass Spectrometry

Ion profiles in polymer light-emitting electrochemical cells are known to significantly affect performance and stability, but are not easily measured. Here, secondary ion mass spectrometry is used to investigate ion profiles in both dynamic and chemically fixed junction devices. Results indicate lower reversibility of dynamic junctions and a more significant time delay for ion redistribution than previously expected, but confirm the complete immobilization of ions in chemically fixed junction devices. When compared with prior studies analyzing the electric field profiles in similar devices, these results help to elucidate the roles of ion distribution and electrochemical doping in LECs.