Lead-Free Antimony-Based Light-Emitting Diodes through the Vapor–Anion-Exchange Method

Hybrid lead halide perovskites continue to attract interest for use in optoelectronic devices such as solar cells and light-emitting diodes. Although challenging, the replacement of toxic lead in these systems is an active field of research. Recently, the use of trivalent metal cations (Bi 3+ and Sb 3+ ) that form defect perovskites A 3 B 2 X 9 has received great attention for the development of solar cells, but their light-emissive properties have not previously been studied. Herein, an all-inorganic antimony-based two-dimensional perovskite, Cs 3 Sb 2 I 9, was synthesized using the solution process. Vapor–anion-exchange method was employed to change the structural composition from Cs 3 Sb 2 I 9 to Cs 3 Sb 2 Br 9 or Cs 3 Sb 2 Cl 9 by treating CsI/SbI 3 spin-coated films with SbBr 3 or SbCl 3, respectively. This novel method facilitates the fabrication of Cs 3 Sb 2 Br 9 or Cs 3 Sb 2 Cl 9 through solution processing without the need of using poorly soluble precursors (e.g., CsCl and CsBr). We go on to demonstrate electroluminescence from a device employing Cs 3 Sb 2 I 9 emitter sandwiched between ITO/PEDOT:PSS and TPBi/LiF/Al as the hole and electron injection electrodes, respectively. A visible–infrared radiance of 0.012 W·Sr –1 ·m –2 was measured at 6 V when Cs 3 Sb 2 I 9 was the active emitter layer. These proof-of-principle devices suggest a viable path toward low-dimensional, lead-free A 3 B 2 X 9 perovskite optoelectronics.