Matched Electron Transport Materials Enabling Efficient and Stable Perovskite Quantum Dot‐based Light‐Emitting Diodes

Here, we report 2,4,6‐Tris(3'‐(pyridine‐3‐yl) biphenyl‐3‐yl)‐1,3,5‐triazine (TmPPPyTz, 3P) with strong electron‐withdrawing moieties of pyridine and triazine to modulate the performance of P‐QLEDs. Compared with commonly used 1,3,5‐Tris(1‐phenyl‐1H‐benzimidazol‐2‐yl)benzene (TPBi), the pyridine in 3P have a strong interaction with perovskites, which can effectively suppress the interface non‐radiative recombination caused by the·Pb2+ defects on the surface of QDs. In addition, 3P have deep highest occupied molecular orbital (HOMO) (enhancing hole‐blocking properties), matched lowest unoccupied molecular orbital (LUMO) and excellent electron mobility (enhancing electron transport properties), realizing the carrier balance and maximizing the exciton recombination. Furthermore, high thermal resistance of·3P obviously improves the stability of QDs under variable temperature, continuous UV illumination, and electric field excitation. Resultantly, the P‐QLEDs using the 3P as ETM achieved an outstanding performance with a champion EQE of 30.2%·and an operational lifetime T50·of 3220 hours at an initial luminance of 100 cd m‐2, which is 151% and about 11‐fold improvement compared to control devices (EQE = 20%, T50 = 297 hours), respectively. These results provide a new concept for constructing the efficient and stable P‐QLEDs from the perspective of selective ETM.