Molecular N‐Type Doping Unlocks Low‐Threshold Nanosecond Lasing in a Microcavity‐Integrated OLED Toward Electrically Pumped Organic Lasers

Abstract

ABSTRACT Organic semiconductors are attractive for the development of flexible, wavelength‐tunable lasers. However, most reported organic micro/nanolasers rely on femtosecond‐pulsed optical pumping, which is impractical for real‐world applications. This limitation has urged the pursuit of electrically pumped organic lasers; yet their realization remains a long‐standing challenge primarily due to a fundamental materials dilemma, in which high‐gain organic semiconductors often suffer from poor, unbalanced charge transport. Here, we demonstrate that this intrinsic trade‐off can be effectively alleviated through a molecular doping strategy. Employing a high‐gain spirofluorene derivative as the emissive layer, we introduce an n‐type doped layer to construct an organic light‐emitting diode (OLED), achieving more balanced charge transport while preserving outstanding optical gain. Consequently, singlet‐polaron annihilation is significantly suppressed, as evidenced by reduced efficiency roll‐off and electrically pumped transient absorption measurements. When integrated with a distributed feedback (DFB) resonator, the resulting device exhibits ultra‐narrow (∼2 nm) electroluminescence under pulsed current injections and delivers low‐threshold nanosecond lasing under an optical–electrical co‐pumping configuration, thereby demonstrating a practical architecture for implementing organic laser diodes. Our work provides a general strategy to overcome the intrinsic paradox where high‐gain organic semiconductors struggle to maintain balanced charge transport, illuminating a pathway toward light amplification under electrical excitation.