TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Device: The device further comprises a substrate. The substrate is a glass or plastic substrate. The device comprises an electron transport layer positioned between the active layer and the cathode. The electron transport layer comprises lithium ferrite or zinc oxide. The anode is a transparent conductive anode. The transparent conductive anode is formed from a layer of a transparent conductive oxide. The oxide is indium tin oxide. The transparent conductive anode is a graphene anode. The device comprises silver anode, hole transport layer containing graphene oxide film as active layer, and indium-tin oxide (ITO) cathode. The cathode is a metal cathode. The cathode is an aluminum cathode. The active layer comprises a blend of an electron accepting material and an electron donating material. The device is an optoelectronic device. The device is an organic optoelectronic device. The active layer comprises a blend of an electron accepting material and an electron donating material and the electron accepting material is a fullerene or fullerene derivative and the electron donating material is a conjugated polymer. The device is a photovoltaic device. The device comprises a glass or plastic substrate. The anode is an indium tin oxide (ITO) anode. The active layer is an active layer comprising a blend of poly(3-hexylthiophene) (P3HT) and phenyl-C61 -butyric acid methyl ester (PCBM) or (2-methoxy-5-(2- ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) layer. The cathode is an aluminum cathode. The thickness of the graphene oxide film is 50 nm or less, preferably 20 nm or less, more preferably 10 nm or less, even more preferably 3.5 nm or less. The GO film thickness is 0.5-20 nm, preferably 0.5-l0 nm, more preferably 0.5-3.5 nm, even more preferably l-3 nm. The device is an organic light-emitting diode. The device comprises plastic substrate e.g. polyethylene terephthalate (PET), graphene anode, hole transport layer comprising a graphene oxide film, an active layer e.g. MEH-PPV layer, and metal cathode e.g. aluminum cathode. EXAMPLE - No suitable example given.