Light-emitting polymer semiconductors in flexible electronics: strategies, challenges and future perspective

Light-emitting polymer semiconductors (LPSs) represent a cornerstone material for next-generation flexible electronics, including wearable displays and health-monitoring devices. However, a fundamental trade-off exists between their mechanical flexibility, essential for stretchable applications, and their optoelectronic performance, governed by rigid conjugated structures. This perspective article critically reviews the recent advancements in strategies developed to resolve this conflict, which are categorized into three primary approaches: intrinsic flexibility engineering (through backbone and side-chain modifications), external plasticization (using small-molecule additives), and elastomer blending. We delve into the implementation mechanisms of each strategy, highlighting their respective merits and limitations in achieving stretchable and efficient light-emitting films. Despite significant progress, key challenges persist, particularly in balancing electrical, optical, and mechanical properties, managing phase separation and interfacial defects, and ensuring interlayer compatibility in full devices. Looking forward, we emphasize that the future development of flexible LPSs hinges on a deeper mechanistic understanding of structure-property relationships and the innovation of functionally elastic and recoverable materials. Overcoming these hurdles will be pivotal for unlocking the full potential of LPSs in practical, durable, and high-performance flexible electronic systems.