High-performance blue TADF OLED using two-step heat plasma-treated MoTe2 as a hole-injection layer

In the pursuit to overcome the limitations posed by traditional hole injection layers (HILs), such as PEDOT: PSS, researchers are focusing on innovative strategies to modify electrode/organic interfaces to facilitate charge-carrier injection and reduce the turn-on voltage, particularly in the context of high-efficiency organic light-emitting diodes (OLEDs). Two-dimensional materials show great potential in addressing the energy barrier challenges at electrode/organic interfaces owing to their exceptional optoelectronic properties and robust chemical stability. However, their implementation in OLEDs has been hindered by complex fabrication processes and work function (WF) mismatches. This study presents a novel approach by introducing a magnetron-sputtered MoTe2 as HIL via two-step O2 doping. This strategy enhances the crystallinity of MoTe2 at a relatively low annealing temperature (350 °C), combined with a plasma-treated anode possessing high WF (approximately 5.05 eV), high transmittance (93% at 478 nm), and low sheet resistance (33 Ω sq−1). Consequently, compared with the conventional blue thermally activated delayed-fluorescence OLED using MoO3 as a HIL, the external quantum efficiency of the manufactured device using MoTe2 as a HIL was improved by 57% and turn-on voltage was reduced to 2.6 V. This study provides a new pathway for overcoming the limitations of conventional solution-based HILs and chemical vapor deposition techniques to industrialize the large-scale manufacturing and commercialization of OLEDs.