Investigation on the Interfaces in Organic Devices by Photoemission Spectroscopy.

Organic semiconductors have garnered significant interest owing to their low cost, flexibility, and suitability for large-area electronics, making them vital for burgeoning fields such as flexible electronics, wearable devices, and green energy technologies. The performance of organic electronic devices is crucially determined by their interfacial electronic structure. Specifically, interfacial phenomena such as band bending significantly influence carrier injection, transport, and recombination, making their control paramount for enhancing device performance. This review investigates the interplay among molecular orientation, interfacial charge transfer, and interfacial chemical reactions as the primary drivers of interface band bending. Furthermore, it critically examines effective strategies for optimizing interfacial properties via interface engineering, focusing on interlayer insertion and template layer methods. The review concludes with a summary and outlook, emphasizing the integration of interface design with material development and device architecture to realize next-generation, high-performance organic electronic devices exhibiting improved efficiency and stability.