Electroluminescent device using two dimensional semiconductor (C/sub 6/H/sub 5/C/sub 2/H/sub 4/NH/sub 3)/sub 2/PpI/sub 4/ as an emitter

Summary form only given. Layered perovskite compounds (RNH/sub 3/)/sub 2/PbX/sub 4/ naturally form quantum-well structure; semiconducting /PbX/sub 4/ layers are separated by organic ammonium layers (RNH/sub 3/). The compounds possess attractive optical properties due to their low-dimensional semiconductor nature, for example, strong excitonic absorption, intense fluorescence from the exciton band, large third-order optical nonlinearity and so on. Further, the optical properties can be adjusted by chemical modification of (RNH/sub 3/) layer and replacing halogen X. In addition, the compounds are processable; one can obtain high-quality thin films of (RNH/sub 3/)/sub 2/PbX/sub 4/ by the spin-coating method. From the advantages, we expected the application of the compounds to electroluminescent (EL) devices. Using one of this type compounds, (C/sub 6/H/sub 5/C/sub 2/H/sub 4/NH/sub 3)/sub 2/PpI/sub 4/(PhEPbI4), we fabricated a multilayered electroluminescent (EL) device consisted of ITO anode, PhEPbI4 emitter layer, electron-transport layer of a oxadiazole derivative(OXD7) and MgAg cathode. PhEPb14 thin film was spin-coated on an ITO-coated glass substrate. Then, OXD7 layer and MgAg were vacuum-deposited successively. In a PhEPbI4 spin-coated film, a strong absorption due to exciton band observed around wavelength of 510 nm, demonstrating formation of layered perovskite structure. Further, green fluorescence with very narrow bandwidth from the exciton band was observed around 520 nm in the film. The bandwidth is less than 20 nm at room temperature. In the device, green EL with very narrow bandwidth was observed. The EL spectrum corresponded well to the fluorescence spectrum of PhEPbI4 thin film. Further, intense EL was attained in the device.