Paper-based photoelectrical devices

With very simple methods, we fabricate photoelectrical devices using a regular paper as substrate; these sensors are able to detect ultraviolet, visible, and infrared radiation using different paper additives. The experiment we made to test detection of ultraviolet and visible light consists in irradiating light of different wavelengths over a device made of paper and semiconductor crystals; electrical current of these devices increases importantly when the bandgap energy of the semiconductor crystal is reached. To test the sensitivity to infrared, we use paper devices impregnated with salts and glycerol to increment its electrical conductivity due to the augmentation of ionic current carriers. We observe that the ionic conductivity on paper increases when the paper is irradiated by infrared light from hot objects; this phenomenon might be due to the molecular structure of cellulose that absorbs energy in the infrared part of the spectrum.