Regulating Charge and Exciton Distribution in High-Performance Hybrid White Organic Light-Emitting Diodes with n-Type Interlayer Switch

The interlayer（IL） plays a vital role in hybrid white organic light-emitting diodes（WOLEDs）; however,only a negligible amount of attention has been given to n-type ILs. Herein, the n-type IL, for the first time,has been demonstrated to achieve a high efficiency, high color rendering index（CRI）, and low voltage trade-off.The device exhibits a maximum total efficiency of 41.5 lm W-1, the highest among hybrid WOLEDs with n-type ILs. In addition, high CRIs（80–88） at practical luminances(C1000 cd m-2) have been obtained, satisfying the demand for indoor lighting. Remarkably, a CRI of 88 is the highest among hybrid WOLEDs. Moreover, the device exhibits low voltages, with a turn-on voltage of only 2.5 V([1 cd m-2), which is the lowest among hybrid WOLEDs. The intrinsic working mechanism of the device has also been explored; in particular, the role of n-type ILs in regulating the distribution of charges and excitons has been unveiled. The findings demonstrate that the introduction of n-type ILs is effective in developing high-performance hybrid WOLEDs.