PEDOT:PSS-Free\nQuantum-Dot Light-Emitting Diode with\nEnhanced Efficiency and Stability

Although high-performance quantum-dot\nlight-emitting diodes (QLEDs)\nhave been achieved, their stability is still limited due to the use\nof unstable PEDOT:PSS as the hole injection layer (HIL). Here, we\ndeveloped a PEDOT:PSS-free QLED by using a binary PTAA:F4-TCNQ HIL.\nBecause the PTAA, with a highest occupied molecular orbital (HOMO)\nlevel of ∼5.20 eV, can facilitate hole injection from ITO to\nthe hole transport layer, and the F4-TCNQ can act as the electron\nacceptor dopant to improve the hole density and hole mobility of PTAA,\nthe PTAA:F4-TCNQ HIL can exhibit excellent hole injection capability.\nAs a result, the PEDOT:PSS-free QLED can exhibit a high EQE of 24.19%\nand an impressive brightness of 367,200 cd/m<sup>2</sup>, which are\nsignificantly higher than those of conventional QLEDs. Moreover, due\nto the improvement of device performance and the removal of PEDOT:PSS,\nthe PEDOT:PSS-free QLED can also exhibit a high <i>T</i><sub>95</sub> operational lifetime of 4206 h at 1000 cd/m<sup>2</sup> and an excellent <i>T</i><sub>80</sub> shelf lifetime\nof 207.41 h at 136400 cd/m<sup>2</sup>, which are about 1.6- and 3.3-fold\nthose of conventional QLEDs, respectively. We believe that the demonstrated\nPEDOT:PSS-free QLED, with higher performance and stability, will promote\nthe practical application of QLEDs in displays.