TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The inorganic nanoparticles comprise metal oxide (zinc oxide, titanium oxide, tantalum oxide, tin oxide, niobium oxide, zirconium oxide, lanthanum oxide, copper oxide, strontium oxide, indium oxide, molybdenum oxide, vanadium oxide, tungsten oxide, nickel oxide, iridium oxide, sodium titanate, cadmium sulfide, gallium arsenide, cadmium selenide, lead sulfide, gallium phosphide, cadmium telluride, and/or tellurium cadmium) and/or a semiconductor compound. The transparent auxiliary layer is in contact with the anode, and the inorganic nanoparticles comprise molybdenum oxide, vanadium oxide, tungsten oxide, nickel oxide, iridium oxide, lanthanum oxide, copper oxide, strontium oxide, and/or indium oxide. The transparent auxiliary layer is in contact with the cathode, and the inorganic nanoparticles comprise zinc oxide, titanium oxide, tantalum oxide, tin oxide, niobium oxide, cadmium sulfide, lead sulfide, indium antimonide, gallium antimonide, aluminum antimonide, cadmium selenide, cadmium telluride, gallium arsenide, aluminum arsenide, indium phosphide, gallium phosphide, and/or aluminum phosphide. An inorganic nanoparticle has a smaller size than a thickness of the transparent auxiliary layer. The transparent auxiliary layer comprises: a first transparent auxiliary layer comprising the inorganic nanoparticles; and a second transparent auxiliary layer comprising the polymer, where the transparent auxiliary layer is a monolayer comprising the inorganic nanoparticles and the polymer. A first surface of the transparent auxiliary layer is in contact with the photoactive layer, and a second surface opposing the first surface of the transparent auxiliary layer is in contact with the anode or the cathode. The organic solar cell (I) further comprises a buffer layer disposed between the photoactive layer and the anode, or between the photoactive layer and the cathode, where the buffer layer comprises a conductive polymer. The photoactive layer comprises a first photoactive layer and a second photoactive layer, and the transparent auxiliary layer is disposed between the first photoactive layer and the second photoactive layer. The organic solar cell (II) further comprises a second transparent auxiliary layer disposed between the first photoactive layer and the second photoactive layer, and comprising the inorganic nanoparticles and the insulating polymer. Preferred Method: The step of providing a transparent auxiliary layer is performed by a solution process. The step of providing a transparent auxiliary layer comprises either: providing the inorganic nanoparticles on the surface of the photoactive layer and separately providing the polymer on the inorganic nanoparticles; or providing a solution comprising both the inorganic nanoparticles and the polymer, on the surface of the photoactive layer.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The polymer comprises an insulating polymer, preferably polyethylene glycol and/or polyethylene oxide. The conductive polymer comprises poly(3,4-ethylenedioxythiophene), polystyrene sulfonate and/or polypyrrole. EXAMPLE - Indium tin oxide (ITO) was laminated on a glass substrate and subsequently washed with each of detergent, distilled water, acetone, and isopropyl alcohol for 10 minutes in ultrasonic waves and dried. Poly(3,4-ethylene dioxythiophene):polystyrene sulfonate was spin-coated on the ITO layer and dried. Then poly(3-hexylthiophene):(6,6)-phenyl C61 butyric acid methyl ester solution was coated and dried to provide a photoactive layer. Polyethylene glycol and zinc oxide particles having a particle size of 5 nm were mixed in a concentration of 1 mg/ml and 15 mg/ml, respectively in methanol and 1-butanol to provide a solution. The solution was spin-coated on the photoactive layer and dried to provide a transparent auxiliary layer which was a monolayer. An aluminum electrode was laminated on the transparent auxiliary layer to give organic solar cell.