Highly Efficient Polymer Light-Emitting devices based on Sodium Compounds Electron Injection Layer

Abstract Enhancing the injection of electron is an effective strategy to improve the performance of polymer light-emitting diodes (PLEDs). In this work, electron injection was improved by inserting sodium compounds NaCl, NaBr, NaI and Na2CO3, respectively, between emissive layer (EML) and electron injection layer (EIL). A maximum 49.6% increase in current efficiency (CE) of PLEDs from 10.85 to 16.24 cd/A was achieved based on NaCl. The Vbi values of PLEDs were investigated to analyze the performance enhancement of PLEDs, which can be ascribed to the migration of Na+. The effect of NaCl, NaBr, NaI and Na2CO3 on the performance of PLEDs were compared to investigate the influence of the anion of sodium compounds. Our work provides an effective and simple method to improve the performance of PLEDs, which is also compatible with the roll-to-roll technology.