Organic light-emitting transistors with high efficiency and narrow emission originating from intrinsic multiple-order microcavities

Narrow electroluminescence is in high demand for high-resolution displays, optical communication and medical phototherapy. Organic light-emitting transistors, as three-terminal electroluminescent devices, offer advantages in simplifying device architecture and achieving high efficiency under gate regulation. However, achieving high efficiency and narrow emission remains a challenge. Here we demonstrate that laterally integrated organic light-emitting transistors with intrinsic multiple-order microcavities can enhance efficiency and narrow emission with a universal capability for different emitters. Full-width at half-maximum values of 18 nm for red, 14 nm for green and 13 nm for blue were achieved with a maximum narrowed degree of 68%. This resulted in an impressive BT.2020 colour gamut of 97%. The peak current efficiency or blue index values for red, green and blue organic light-emitting transistors reached 26.3 cd A⁻¹, 37.3 cd A⁻¹ and 72.6, respectively. Moreover, organic light-emitting transistors exhibit much narrower emission and higher efficiency than equivalent, comparable devices due to their unique gate regulation capability. Our work could enable smart display technologies with high colour purity and enhanced efficiency.