TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The transparent conductive intermediate layer has resistivity of 10-1-10-6 ohmx cm or sheet resistance of 1 ohm/square to 100 Mohm/square, and average thickness of 0.1 nm to 1 mm. The transparent conductive intermediate layer comprises metals including titanium, zirconium, strontium, zinc, indium, lanthanum, vanadium, molybdenum, tungsten, tin, niobium, magnesium, calcium, barium, aluminum, yttrium, scandium, samarium, gallium, fluorine and strontium titanium, or their oxides, preferably indium tin oxide, fluorine tin oxide, antimony tin oxide, gallium-tin oxide, zinc oxide-gallium(III) oxide or zinc oxide-aluminum oxide, alloys, complex oxides or nanoparticles. The tandem solar cells comprise multilayer structure formed by repeatedly stacking the amorphous silicon layers, the transparent conductive intermediate layers or the organic photoactive layers, or p-type amorphous silicon layer formed on conductive substrate (10), i-type amorphous silicon layer formed on p-type amorphous silicon layer, n-type amorphous silicon layer formed on the i-type amorphous silicon layer, the transparent conductive intermediate layer formed on n-type amorphous silicon layer, a hole transport layer (60) formed on the transparent conductive intermediate layer, the organic photoactive layer formed on the hole transport layer, an electron transport layer (80) formed on the organic photoactive layer, and metal electrodes formed on the electron transport layer. The hole transport layer comprises conductive inorganic material including copper(ii) oxide, nickel(II) oxide, molybdenum trioxide and tungsten trioxide, or conductive polymers including poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate), polyaniline or polypyrrole. The electron transport layer comprises metals including titanium, zirconium, strontium, zinc, indium, lanthanum, vanadium, molybdenum, tungsten, tin, niobium, magnesium, calcium, barium, aluminum, yttrium, scandium, samarium, gallium, fluorine and strontium titanium, or their oxides, alloys, complex oxides or nanoparticles. The metal electrodes comprise metals including aluminum, calcium, magnesium, gold and sliver. Preferred Method: The method comprises forming the p-type amorphous silicon layer on conductive substrate, forming i-type amorphous silicon layer on the p-type amorphous silicon layer, forming n-type amorphous silicon layer on the i-type amorphous silicon layer, forming transparent conductive intermediate layer on the n-type amorphous silicon layer, forming the hole transport layer on the transparent conductive intermediate layer, forming the organic photoactive layer on the hole transport layer, forming the electron transport layer on the organic photoactive layer, and forming metal electrodes on the electron transport layer.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The organic photoactive layer comprises: at least one conjugated polymer, preferably poly(3-hexylthiophene-2,5-diyl), (6,6)-phenyl-61C-butyric acid methyl ester, poly(3-octylthiopene-2,5-diyl), poly(3-alkylthiophene), poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-(phenylenevinylene) and poly(2-methoxy-5-(3',7'-dimethyloctyloxy))-1,4- phenylenevinylene), poly(2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta(2,1-b,3,4-b')-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)), poly(thieno(3,4-b)thiophene-benzodithiophene) and poly(4,8-bis-benzo(1,2-b:4,5-b')dithiophene-2,6-diyl-alt-4-thieno(3,4-b)thiophene-2,6-diyl); and fullerene derivatives comprising (6,6)-phenyl-C61-butyric acid methyl ester, bisadduct of phenyl-C61-butyric acid methyl ester, (6,6)-phenyl-C71-butyric acid methyl ester and indene-C60 bisadduct. The substrate is plastic substrate, preferably polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, aromatic polyester and polyimide, glass substrate, quartz substrate, silicon substrate, metal substrate or gallium arsenide substrate.