High Brightness and Enhanced Stability of CsPbBr 3 ‐Based Perovskite Light‐Emitting Diodes by Morphology and Interface Engineering

A CsPbBr 3 ‐based all‐inorganic perovskite light‐emitting diode (PeLED) with ultrahigh brightness and enhanced stability is prepared by controlling of morphology and interface engineering. A nonionic surfactant polyoxyethylene (20) sorbitan monolaurate is introduced into the CsPbBr 3 film, which induces tightly arranged grains in the perovskite film, thus highly passivating the defects at the grain boundaries, resulting in a performance‐enhanced PeLED with a highest brightness of 111 000 cd m −2 , a peak current efficiency (CE) of 21.1 cd A −1 , a maximum external quantum efficiency (EQE) of 5.55%, and an operational lifetime of 4.5 h. The device properties are further improved by adding an anionic surfactant sodium dodecyl benzene sulfonate to modify the hole injection layer poly(ethylenedioxythiophene):polystyrenesulfonate. The hole current density is increased, further balancing the charge injection and transport. Finally, the optimal device displays an ultrahigh brightness of 179 000 cd m −2 , a peak CE of 28.0 cd A −1 , a maximum EQE of 7.39%, and a further prolonged lifetime of 6 h.