Photochromic Materials Towards Energy Harvesting

Solar to electrical energy conversion is one of the possible approaches regarding energy demand and sustainability. While traditional semiconductor photovoltaic units are seen to be well implemented in the market, with companies offering packs for both domestic and industries, the search for new materials and technologies aiming improvement in efficiency together with low cost issues has been continuously stressed over the past 20 years. This work point out a novel approach for energy conversion and storage devices, based on the so called photochromic electrets or photoelectrets, by using materials containing highly polarisable molecules as multifunctional diarylethenes (DTEs) and azobenzenes. This is supported by experimental results which show that (1) DTE-CN blends after electrical field induced orientation are able to induce external current response when submitted to visible light pulse (2) visible light is able to induce birefringence in layer-by-layer (LbL) films of poly{1-(4-(3-carboxy-4-hydroxy-phenylazo) benzenesulfonamido)-1,2-ethanediyl, sodium salt}(PAZO) and poly (allylamine hydrochloride) (PAH). These preliminary results allow to conclude that solar devices based on photoelectrets are worth to be further investigated towards energy harvesting.