TECHNOLOGY FOCUS - ELECTRONICS - Preferred Device: In the device, the semiconductor nanoparticles comprise covalent or ionic, amorphous or nanocrystalline particles. The deposition of the suspension is by inkjet printing. The substrate (1) is flexible. The device further comprises electrodes (2, 7, 8). The suspension comprises semiconductor nanoparticles dispersed in a liquid medium comprising a solvent and a combination of none, one, two or more of the following: surfactant, component for adjusting viscosity, dispersant, and binder. The semiconductor nanoparticles comprise: (a) organic materials comprising tetracene, pentacene, Copper Ftalocianine, Titania Ftalocianine and zinc Ftalocianine; and/or (b) inorganic materials comprising binary, ternary or quaternary, n-type oxides of zinc (Zn), titanium (Ti), niobium (Nb), molybdenum (Mo), tantalum (Ta), tungsten (W), indium (In), gallium (Ga), tin (Sn), aluminum (Al) or p-type oxides of copper (Cu), Sn, nickel (Ni), rhodium (Rh), silver (Ag) and iridium (Ir), either stoichiometric or non stoichiometric. The suspension comprises dispersed titanium dioxide (TiO2) anatase nanoparticulate paste 0.01-0.4 w/w, dispersant 0.001-0.02 w/w, binder 0-0.03 w/w, and solvent ethanol. The suspension comprises dispersed TiO2 anatase nanoparticulate paste 0.05-0.15 w/w, dispersant 0.05-0.1 w/w, plasticizer 0.01-0.05 w/w, binder 0.01-0.05 w/w, and solvent methanol. The suspension comprises dispersed TiO2 anatase nanoparticulate paste 0.1-0.4 w/w and as solvent a mixture of ethano1 and water in proportion 10:90 to 50:50. The suspension comprises as solvent a mixture of water and isopropyl alcohol. The suspension also comprises: one or more additives suitable for reducing the layer transfer resistance; up to 0.5 w/w: nanoparticles of conductive metal oxide nanoparticles, metal nanoparticles, indium titanium oxide (ITO), FTO, tin dioxide (SnO2), zinc oxide (ZnO) or niobium oxide (Nb2O5). The intervening space, available between the electrodes (2, 7, 8), available between the electrodes (2, 7, 8) and the pillars (3), and also available in the pores of the pillars, comprises a filler (6) which comprises a passive semiconductor: or a solid, gel or liquid state ion conductor; or a polymer electrolyte. The pillars (3) are arranged in arrays where the pillar height is 20-8000 mu m, the inter-pillar distance is 20-800 mu m, the pillar diameter is 20-900 mu m. The pillars (3) are arranged in arrays where the pillar height is 50-200 mu m, the inter-pillar distance is 500-1000 mu m, the pillar diameter is 40-60 mu m. The device further comprises a second substrate (1), a first electrode (2) between the first substrate (1) and the pillars (3), a second electrode (2) between the second substrate (1) and the pillars (3) a count electrode (8) between the second electrode (2) and the pillars (3), an ion conductor (6) in the intervening spaces between the counter electrode (6) and the pillars (3). Moreover, the device comprises an electrical contact (7) between the substrate (1) and the pillars (3), a counter electrode (8) lateral to the pillars (3) along the substrate (1) direction in a contact-less meshing arrangement with the pillars (3), an ion conductor (6) in the intervening spaces between the counter electrode (6) and the pillars (3). The substrate (1) comprises paper, metal foils, vitroceramics, mylar, glass, polyethylene terephthalate (PET), or polyethylene nitrate (PEN). Preferred Method: Producing the optoelectronic device further comprises adjusting the driving parameters of the printing head, the delay between two successive layers, and the substrate temperature in order to prevent the coalescence of neighboring pillars; and stirring, ultrasonic dispersing and filtrating of the suspension.