Enhanced efficiency of all-inorganic perovskite light-emitting diodes by using F4-TCNQ-doped PTAA as a hole-transport layer

We demonstrate an enhanced efficiency of all-inorganic perovskite light-emitting diodes (PeLEDs) by doping an electron acceptor of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) as a p-type dopant into the hole-transport layer (HTL) of poly-triarylamine (PTAA). The conductivity of the PTAA was improved by the formation of the CT complex through the electron transfer from the PTAA to F4TCNQ. Moreover, the hydrophobic surface of the PTAA leads to an improved surface morphology of the perovskite films compared to that on the conventionally used HTL of PEDOT:PSS. As a result, the maximum luminance and efficiency for the doped PTAA-based PeLEDs are 28020 cd/m² and 13.5 cd/A, respectively, corresponding to 32.7% and 48% improvement in the efficiency compared to those of the pure PTAA or PEDOT:PSS-based PeLEDs.