Efficient Orange Light-Emitting Diodes from Nontoxic Organic–Inorganic Hybrid Copper Halides Enabled by Nonionic Surfactant Chemisorption

Ternary copper halides with an eco-friendly property have emerged as attractive candidates to replace toxic lead-containing perovskites for light-emitting diodes (LEDs), yet achieving long-wavelength electroluminescence remains unexplored. Herein, we report the first realization of orange-emitting LEDs (595 nm) based on nontoxic organic-inorganic PEA4Cu4I4 (PEA = β-phenylethylamine) films enabled by a nonionic surfactant poly(propylene glycol) bis(2-aminopropyl ether) (APPG) chemisorption. Experimental and theoretical analyses rationalize that the APPG additive has strong chemisorption with the Cu-I framework within the grain boundaries of PEA4Cu4I4 films, which not only improves the film's morphology but also passivates the iodine vacancy defects. Moreover, the APPG additive can raise the ionization energy and increase the carrier mobility of PEA4Cu4I4 films, thereby balancing the charge transport. Consequently, we achieve orange LEDs made from APPG-treated PEA4Cu4I4 films, showing an external quantum efficiency of 1.21%, and the operational stability of the treated device is greatly prolonged, resulting from the suppressed iodine ion migration.