(a) Schematic of parallel alternating-current electroluminescent (AC EL) devices with four different metal electrodes. (b) Luminance versus voltage characteristics (L–V) of the devices shown in a photograph in the inset. The scale bar is 5 mm. (c) Maximum luminance and current density characteristics of the devices with four metal electrodes. (d) Photograph of a field-induced organic light emitting board (OLEB) with two parallel indium tin oxide (ITO) bottom electrodes guided with dotted boxes in white. The scale bar is 5 mm. (e) Schematic of a writable OLEB using a conductive pencil. (f) Photographs of electroluminescent (EL) images visualizing metallic characters and symbols written by both PEDOT:PSS ink (top two photographs) and silver pastes (bottom two photographs). The scale bar is 5 mm. (g) Schematics of visualization of a metallic micropattern on the board by physical contact. (h) A photograph of an OLEB on which a patterned Au on a poly(dimethyl siloxane) (PDMS) substrate was in conformal contact. An optical microscope (OM) image on the right side shows the patterned EL arising from the metallic pattern on the board. The scale bar is 5 mm (left) and 50 μm (right). All the results were obtained with the alternating-current frequency of 100 kHz.