Efficient all-thermally evaporated perovskite light-emitting diodes for active-matrix displays

Perovskite light-emitting diodes (PeLEDs) have recently demonstrated great potential for next-generation displays. Fabricating PeLEDs by scalable and well-established thermal evaporation—the technique used for industrial manufacturing of organic light-emitting diodes—should accelerate the development of perovskite displays; however, thermal evaporation of perovskites produces films with a high density of defects due to fast and uncontrollable crystal growth during evaporation. As a result, the performance of evaporated PeLEDs is lagging behind their solution-processed counterparts. Here we develop a tri-source co-evaporation strategy to introduce a multifunctional Lewis-base additive that reduces the perovskite grain size while confining charge carriers and passivating surface defects. The process enables the in situ formation of high-quality perovskite nanocrystal films with improved crystallinity, enhanced photoluminescence quantum yield and suppressed defects. A peak external quantum efficiency of 16.4% is achieved for green PeLEDs with an all-thermally evaporated device architecture. We further fabricate active-matrix PeLED displays by integrating top-emitting PeLEDs on a 6.67-inch thin-film transistor backplane. The displays show high-definition images and videos with a resolution of 1,080 × 2,400 and continuous greyscale information. We anticipate that this work will stimulate the exploration of efficient vapour-deposited PeLEDs for industrial display applications.