Quantized Electrode for Robust Organic Devices

The contact between inorganic electrodes and organic layers serves as both a charge-carrier conduit and a crucial topological link in organic optoelectronic devices, significantly impacting carrier injection/extraction efficiency and long-term stability. A barrier-free contact for hole injection with thermodynamic stability at the inorganic electrode/organic interface is essential for efficient devices. However, this has not yet been realized between metal electrodes and organic materials with high ionization energy (IE). Here we demonstrate a quantized electrode with surface charge-transfer states formed by chemisorbed ultrathin organic layer on an aluminum surface. This quantized electrode, featuring a new injection mechanism, forms universal ohmic hole contacts with organic semiconductors possessing high IEs up to 6.1 eV, rendering the conventional rule of ohmic hole contact that the work function of the anode must match the IE of the organic semiconductor invalid. The resultant organic light-emitting diode (OLED) achieves ultrahigh luminance at low voltage and extremely low efficiency roll-off. Moreover, the quantized electrode exhibits excellent thermal stability, with a seventeen-fold increase in operational lifetime compared to the reference device. Quantized electrodes will facilitate the development of OLED microdisplays and have potential applications in other advanced semiconductors requiring ohmic hole contact and robust stability.