Ultrahigh-radiance near-infrared organic light-emitting diodes

Near-infrared organic light-emitting diodes are attractive for a broad range of applications, including night-time surveillance and biomedical diagnostic and imaging systems. However, obtaining high device radiance, which is necessary for many applications, and maintaining high operational stability is challenging due to the rapid efficiency roll-off at a high current density. Here we develop near-infrared organic light-emitting diodes based on an acceptor–donor–acceptor organic semiconductor with greatly suppressed singlet–triplet annihilation rate and triplet lifetime, alleviating singlet quenching by long-lived triplets, thereby enabling an ultrahigh singlet density at high electrical excitation levels. Our devices exhibit J₅₀ values of 59.2 A cm⁻², that is, the current density at which the external quantum efficiency decreases to half its peak value of 1.34%. A high external quantum efficiency is also maintained over a six orders of magnitude range of current densities, at values above 5,000 A cm⁻². The devices emit with the maximum radiance beyond 2,000 W sr⁻¹ m⁻² under a continuous electrical bias and 46,700 W sr⁻¹ m⁻² in the pulsed electrical operation. The half-lifetime is 35 h for an initial radiance of 100 W sr⁻¹ m⁻². We also achieve a high electrically injected singlet density of more than 10¹⁶cm⁻³ at 1,000 A cm⁻², which can sustain population inversion, indicating potential for organic lasers. These results pave the way for further developments of near-infrared organic light-emitting diodes as well as offer a potential route towards electrically driven organic laser diodes.