Lithium and Sodium Stearates as Electron Injection Materials in Organic Light-Emitting Diodes

Despite being efficient electron injection for the organic light-emitting diode, sub-nanometer ultrathin layer of lithium fluoride requires deposition at high temperature and precise layer thickness. Nontoxic organometallic compounds such as lithium stearate and sodium stearate are tested for electron-injection alternatives, which can be deposited at lower temperatures. In this work, OLEDs with lithium or sodium stearates arc found to perform better than the lithium fluoride as electron injection. These devices also manage to achieve 90% maximum luminance and power efficiencies over a broader range of 1.5 - 4.5 nm thick of lithium stearate and 2.5 - 4.0 nm thick of sodium stearate.