Boosted electroluminescence of perovskite light-emitting diodes by pinhole passivation with insulating polymer

Organic–inorganic hybrid perovskites are emerging as promising light-emitting materials due to their superior photophysical properties. Poor surface coverage creating substantial pinholes and shunt paths, nevertheless, is one of the most severe problems that hinder the further development of perovskite light-emitting diodes (PeLEDs). Here in this work, we demonstrated a fabrication of PeLEDs by using a robust, stable, and highly transparent poly(methyl methacrylate) (PMMA) polymer to passivate the pinholes of CH3NH3PbBr3 emissive layer and hence reduce the non-radiative losses through the shunt paths formed by the pinholes. Uniform surface coverage and reduced leakage current were achieved. Green electroluminescence (EL) emission centered at ~534 nm was greatly boosted by a factor of 10 at 8 V with optimizing the thickness of the PMMA modifier. This facile and universal technique provides an effective way to circumvent the poor formation of the CH3NH3PbBr3 perovskite film and may be very helpful in the development of PeLEDs.