Self-Reinforcing Degradation of Solution-Processed Small-Molecule OLEDs: Excited-States and Molecular Interactions as Key Triggers

Abstract

Solution-processed organic light-emitting diodes (SOLEDs) are promising candidates for cost-efficient and scalable displays, if their operational stability can be increased to match that of thermal-evaporation-processed OLEDs. This study provides a comprehensive analysis of the fundamental degradation mechanisms in SOLEDs. This work reveals a self-reinforcing degradation cycle in which charge accumulation in molecular aggregates and hetero-interfaces strengthens exciton-polaron interactions, thereby promoting further molecular aggregation and nonradiative exciton annihilation. This work applies material engineering strategies, including the use of host-guest combination with minimal intermolecular interactions, modification of the hole injection interface, and suppression of self-reinforcing degradation pathway to obtain SOLEDs that have luminous efficiency exceeding 100 cd A-1 and a half lifetime of over 700 h. These findings establish a strategic approach to increase SOLED efficiency and longevity, while offering insights into the design principles required for next-generation organic optoelectronic devices.