DFT study to discover new EIL materials based on the quinolate derivatives involving S and Se atoms.

We designed a series of new EIL molecules based on the Liq. As a simple design strategy, S and Se atoms were utilized to replace O atom of quinolate moiety. Additionally, the quinolate derivatives including S and Se atoms with singly oxidized metal ions (Na, K, Rb, Cs, Ag, and Au) were also designed. The DFT and TDDFT calculations were performed to understand the charge transport, and photophysical properties of designed molecules. As a result, the AuSq and AuSeq are expected to provide benefits to develop the OLED device performance. First, faster electron hopping rate and lower injection barrier are expected to increase the amount of electron carriers into EML, which crucially helps to improve the exciton recombination rate and J-V characteristic. Eventually, the external quantum efficiency and power efficiency are expected to increase. Moreover, these designed molecules hardly absorb any primary colors, thereby they don't reduce the out-coupled light photons. Based on these results, we strongly suggest that AuSq and AuSeq can be utilized as alternative EIL material to achieve the superior performance in OLED devices.