Efficient Blue Perovskite Light-Emitting Diodes Enabled by Buried Interlayer Modulation

Perovskite light-emitting diodes (PeLEDs) have shown great potential in next-generation display and lighting applications due to their outstanding optoelectronic properties. However, the performance of blue PeLEDs still lag far behind their green and red counterparts, suffering from the inefficient hole injection and severe trap-assisted nonradiative recombination. Here, we proposed a buried interlayer modulation strategy to address these issues simultaneously by inserting a guanidinium sulfate (GS) layer between the hole transport layer and perovskite emitting layer in PeLEDs. The S=O functional groups of GS molecules will form coordination with dangling lead ions, suppressing interfacial non-radiative recombination. Meanwhile, the amino groups can enhance hole injection via hydrogen bonding with halide anions. Consequently, the resulting blue PeLEDs achieves a maximum external quantum efficiency (EQE) of 15.5% at 478 nm, and a half-lifetime of 112 minutes at an initial brightness of 100 cd m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup>, which are 1.7-fold and 10-fold higher than those for the reference device, respectively.