Hybrid organic zinc oxide white-light-emitting diodes on disposable paper substrate

Abstract

ZnO–organic hybrid white-light-emitting diodes (WLEDs) were demonstrated on a paper substrate. The configuration used for ZnO–organic hybrid WLEDs consists a layer of poly (9,9)-(dioctylfluorene) (PFO) on poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate) (PEDOT: PSS) on n-type ZnO nanorods grown by a low-temperature chemical aqueous method on paper substrate. Room temperature photoluminescence, electroluminescence, and cathodoluminescence (CL) spectra reveal a broad visible region covering the range from 420 to 800 nm. By using room temperature-CL, we got luminescence information, especially to verify the origin of specific emissions, the internal absorption of the ultraviolet and the spatial distribution of radiative defects. It was observed that the visible wavelength range depends on the penetration depth of the excitation. This suggests that the concentration of deep levels responsible for the visible luminescence is at the sample surface to a depth of 1–2 µm when using an accelerating voltage up to 20–30 kV. The results indicate that demonstration of WLEDs on paper substrate with reasonable electrical performance greatly influences the reduction of substrate cost, furthermore, this may open way to fabricate optoelectronics devices on disposable substrates for large-area applications.