Blue Transparent OLEDs with High Stability and Transmittance for Modulating Sleep Disorders

Optoelectronics devices utilizing organic light-emitting diodes (OLEDs) are emerging as new platforms for healthcare applications. In particular, wearable optoelectronics such as visual stimulus systems offer a distinctive advantage to intervene in and improve sleep disorders. In this study, two improvements are proposed for transparent OLEDs (TrOLEDs) that will be critical for visual applications. First, zinc sulfide with high surface energy and a high refractive index is explored as a seed and capping layer. An ultra-thin silver cathode of 8 nm is demonstrated to be feasible in TrOLEDs, and luminous transmittance of 91% is achieved. Second, in general, achieving the operational stability of TrOLEDs with high transmittance is challenging due to the vulnerability of thin electrodes. By introducing a doping process to the electron transport layer, a lifetime comparable to that of control OLEDs with thick cathodes (>90%) is secured. Last, a preclinical model using blue light is proposed to modulate sleep patterns. Melanopsin is stimulated at the highest level of sleep desire, reducing non-rapid eye movement sleep duration in mice by up to 14%. Based on these results, the proposed TrOLEDs are promising candidates for modulating sleep disorders such as insomnia and narcolepsy-cataplexy with the convenience of wearable form factors.