High-performance planar green light-emitting diodes based on a PEDOT:PSS/CH3NH3PbBr3/ZnO sandwich structure

Abstract

Recently, perovskite-based light-emitting diodes based on organometal halide emitters have attracted much attention because of their excellent properties of high color purity, tunable emission wavelength and a low-temperature processing technique. As is well-known, organic light-emitting diodes have shown powerful capabilities in this field; however, the fabrication of these devices typically relies on high-temperature and high-vacuum processes, which increases the final cost of the product and renders them uneconomical for use in large-area displays. Organic/inorganic hybrid halide perovskites match with these material requirements, as it is possible to prepare such materials with high crystallinity through solution processing at low temperature. Herein, we demonstrated a high-brightness green light-emitting diode based on PEDOT:PSS/CH₃NH₃PbBr₃/ZnO sandwich structures by a spin-coating method combined with a sputtering system. Under forward bias, a dominant emission peak at ∼530 nm with a low full width of half-maximum (FWHM) of 30 nm can be achieved at room temperature. Owing to the high surface coverage of the CH₃NH₃PbBr₃ layer and a device design based on carrier injection and a confinement configuration, the proposed diode exhibits good electroluminescence performance, with an external quantum efficiency of 0.0645%. More importantly, we investigated the working stability of the studied diode under continuous operation to verify the sensitivity of the electroluminescence performance to ambient atmosphere and to assess the suitability of the diode for practical applications. Moreover, the underlying reasons for the undesirable emission decay are tentatively discussed. This demonstration of an effective green electroluminescence based on CH₃NH₃PbBr₃ provides valuable information for the design and development of perovskites as efficient emitters, thus facilitating their use in existing applications and suggesting new potential applications.