White Light Emission from a Highly Flexible ZnS Composite Mixed with Polymer Composites Under the AC Electric Field

We fabricated a flexible white light emitting device by mixing a fabricated zinc sulphide (ZnS) composite (ZnS: Al, Cu, Mn) and polydimethylsiloxane (PDMS) between the thin silver plastic electrodes. The emitted light was analyzed by a spectrometer according to the AC frequency and the applied voltage. The electroluminescence spectrum of the flexible device were measured in the wavelength range of 350 nm ~ 750 nm at the room temperature. By using the deconvolution method, it was confirmed that the measured white light was composed of four superimposed electroluminescent peaks. The CIE color coordinates of the white light were changed according to the applied frequency due to the excitation energy difference. The color coordinate of the observed white light was (0.30, 0.33) at an applied voltage of 200 V at 300 Hz, which is close to the color coordinate value of the ideal white light.