Near Infrared to Visible Electroluminescent Diodes Based on Organometallic Halide Perovskites: Structural and Optical Investigation

In this paper we present a study of the structural, electrical, and optical properties of four different 3D organometallic halide-based perovskite semiconductors with band gaps varying from NIR to visible at room temperature. Electroluminescent devices (using a solution process) with these perovskites as the active layer are also demonstrated. The morphology and crystallinity of the perovskite depends on the halide ion and substrate wetting conditions, where crystallite size varies from ∼100s nm to few micrometers. We found it has a huge influence on the optical properties and performance of light emitting diodes (LEDs) using these perovskites as the active layer. Photoluminescence studies in the presence of commonly used charge injection layers are also studied and we correlate these results with performance of PeLEDs. We also demonstrate additional control of the electroluminescence emission by the formation of new complexes with organic hole transport layers. Finally, we clarify the diverse electronic charge transport in these perovskites. These results show promise of a new materials regime for LEDs.