Efficient And Flexible Light-emitting Diodes Based On Nucleation And Crystallization Regulation Of Perovskite Grains

Perovskite light-emitting diodes have the advantages of high color purity,simple manufacturing processes,and tunable bandgap.In recent years,flexible devices have gradually become a major trend in the electronic field,which could be used in solid-state lighting,foldable screen displays,and bio-integrated electronics,showing unlimited application potential.Although the efficiency of traditional flexible devices has increased yearly,there are still some problems,such as electrode fracture,poor crystallization of thin films,and poor mechanical properties of devices.To address the above issues,the following three tasks have been carried out:(1)To overcome the defects of traditional electrode indium tin oxide,such as high brittleness and complicated preparation process.In this work,a semi-embedded transparent flexible PI/AgNWs electrode is designed,which effectively solves the problem of electrode protrusion and falling off,has excellent light transmission and its square resistance is 20 Ω/sq.The electrode can also be combined with an elastomer,a 2D stretchable electrode with spontaneous wrinkles was successfully prepared by utilizing the stretchability of the elastomer.(2)The natural brittleness of perovskite and its unrepair grain boundary cracks in the perovskite films are the biggest challenges to realizing flexible perovskite light-emitting diodes.In this work,a self-healable perovskite film is designed by introducing polyurethane with dynamic hydrogen bonds into the perovskite precursor solution,the crystallinity of the perovskite film is enhanced,and the cracks of grain boundary are also filled.Finally,a flexible sky-blue emission perovskite light-emitting diode based on PI/AgNWs electrode with an efficiency of 13.5%is obtained,and the device can still maintain 87.8%and 80.7%of the initial efficiency after 2000 bending and torsion cycle tests.(3)To solve the problem of poor crystallization of perovskite films on flexible substrates.In this paper,a perovskite film with high crystallinity and flatness by introducing natural silk protein is designed.The β-sheet conformation of silk protein reduces the nucleation barrier of perovskite grains and optimizes the crystallization properties of perovskite film.A flexible blue emission perovskite light-emitting diode based on PI/AgNWs electrode with an efficiency of 12.7%was realized.