Efficient Charge Generation Assistant Layer for Tandem Organic Light Emitting Diodes Using Ytterbium–Silver Alloy

Tandem organic light-emitting diodes (OLEDs) are an innovative and promising technology aimed at enhancing the luminance and extending the lifespan of OLED applications. A significant challenge in their development lies in achieving high-performance charge-generation layers (CGLs). In this study, the use of a yetterbium-silver (Yb:Ag) alloy is proposed as an assistant layer within the CGL to improve the injection of generated electrons into the electron transport layer (ETL). This enhancement is confirmed through capacitance–voltage measurements and work function analysis. Moreover, the Yb:Ag layer exhibits exceptional optical transmittance and surface uniformity. Tandem devices fabricated with the Yb:Ag alloy assistant layer exhibited a significant reduction in operating voltage, approximately halving it compared to tandem devices without a metal assistant layer. This resulted in a 2.13-fold increase in luminous efficiency and a 1.07-fold improvement in power efficiency compared to a single-unit device. Thus, the integration of a Yb–Ag alloy as a CGL assistant layer is a promising strategy for improving the performance and viability of tandem OLED technologies, underscoring its potential impact on next-generation displays and lighting applications.