Mixed-type heterojunction thin-film solar cell structure and method for fabricating the same

Abstract

The present invention discloses a mixed-type heterojunction thin-film solar cell structure and a method for fabricating the same. Firstly, a conductive substrate and a template are provided, and the template has a substrate and an inorganic wire array formed on the substrate. Next, a conjugate polymer layer is formed on the conductive substrate. Next, the inorganic wire array is embedded into the conjugate polymer layer. Next, the substrate is separated from the inorganic wire array. Then, an electrode layer is formed over the inorganic wire array and the conjugate polymer layer. The solar cell structure of the present invention has advantages of flexibility, high energy conversion efficiency and low fabrication cost.

1 . A mixed-type heterojunction thin-film solar cell structure comprising
 a conductive substrate;   a conjugate polymer layer formed on said conductive substrate;   an inorganic wire array inserted into said conjugate polymer layer but not contacting said conductive layer; and   an electrode layer covering said inorganic wire array and said conjugate polymer layer.   
     
     
         2 . The mixed-type heterojunction thin-film solar cell structure according to  claim 1 , wherein a hole blocking layer is formed in between said conjugate polymer layer and said electrode layer to cover said conjugate polymer layer and said inorganic wire array, said hole blocking layer is made of a material selected from a group consisting of ZnO (Zinc Oxide), TiO x  (titanium oxide), PCBM ((6,6)-phenyl C 61  butyric acid methyl ester), LiF (Lithium Fluoride), a calcium compound and an alkali compound, wherein said alkali compound is Li 2 O, LiBO 2 , K 2 SiO 3 , or Cs 2 CO 3 . 
     
     
         3 . The mixed-type heterojunction thin-film solar cell structure according to  claim 1 , wherein a non-conductive layer is formed in between said conjugate polymer layer and said electrode layer to protect said inorganic wire array; said non-conductive layer has such a thickness that said inorganic wire array emerging from said conjugate polymer layer is higher than said non-conductive layer; said non-conductive layer is made of a transparent material or an opaque material; said transparent material is one of following materials: PMMA (polymethylmethacrylate), SOG (Spin-On Glass), SiO 2  (silicon dioxide), and Si 3 N 4  (silicon nitride). 
     
     
         4 . The mixed-type heterojunction thin-film solar cell structure according to  claim 3 , wherein a hole blocking layer is formed in between said non-conductive layer and said electrode layer to cover said non-conductive layer and said inorganic wire array, said hole blocking layer is made of a material selected from a group consisting of ZnO (Zinc Oxide), TiO x  (titanium oxide), PCBM ((6,6)-phenyl C 61  butyric acid methyl ester), LiF (Lithium Fluoride), a calcium compound and an alkali compound, wherein said alkali compound is Li 2 O, LiBO 2 , K 2 SiO 3 , or Cs 2 CO 3 . 
     
     
         5 . The mixed-type heterojunction thin-film solar cell structure according to  claim 1 , wherein spacing between two wires of said inorganic wire array is below two times diffusion length of excitons in polymer. 
     
     
         6 . The mixed-type heterojunction thin-film solar cell structure according to  claim 1 , wherein length of wires of said inorganic wire array is adjusted according to an absorption coefficient of an inorganic material of said inorganic wire array. 
     
     
         7 . The mixed-type heterojunction thin-film solar cell structure according to  claim 1 , wherein at least one hole transport layer or at least one electron blocking layer is formed in between said conductive substrate and said conjugate polymer; either of said hole transport layer and said electron blocking layer does not contact said inorganic wire array. 
     
     
         8 . The mixed-type heterojunction thin-film solar cell structure according to  claim 1 , wherein said inorganic wire array is a nanometric structure, a micron structure, or a submicron structure. 
     
     
         9 . The mixed-type heterojunction thin-film solar cell structure according to  claim 8 , wherein when said inorganic wire array is a micron structure or a submicron structure, nanowire structures are formed on said micron structure or said submicron structure to increase contact area between said conjugate polymer layer and said inorganic wire array. 
     
     
         10 . The mixed-type heterojunction thin-film solar cell structure according to  claim 1 , wherein said inorganic wire array is made of a material selected from a group consisting of silicon, germanium, gallium arsenide, indium phosphide, gallium phosphide, gallium antimonide, zinc telluride, indium gallium nitride, a single element, a binary compound semiconductor, and a compound semiconductor containing more than two components; said conjugate polymer layer is made of a material selected from a group consisting of P3HT (poly-3-hexylthiophene), MEHPPV (poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene]), PCPDTBT (poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)]), OC 1 C 10 -PPV (Poly[2-(3,7-dimethyloctyloxy)-5-methoxy-p-phenylene vinylene]), MDMO-PPV (poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene]), and polyfluorene; said conductive substrate is made of one of following materials: a transparent conductive substrate, a transparent-electrode glass substrate, a transparent-electrode plastic substrate, a transparent-electrode quartz substrate and a thin metallic plate; said electrode layer is made of a metal, a transparent-electrode material, or a material selected from a group consisting of ITO (Indium Tin Oxide), GITO (Gallium Indium Tin Oxide), ZITO (Zinc Indium Tin Oxide), FTO (Fluorine-doped Tin Oxide), ZnO (Zinc Oxide), AZO (Aluminum Zinc Oxide) and IZO (Indium Zinc Oxide). 
     
     
         11 . The mixed-type heterojunction thin-film solar cell structure according to  claim 7 , wherein said hole transport layer is made of a material selected from a group consisting of PEDOT (Poly(3,4-ethylenedioxythiophene)), PEDOT: PSS (Poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate)), TFB:TPDSi 2  (poly[9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine]: 4,4′-bis[(p-trichlorosilylpropylphenyl)phenylamino]biphenyl), CuPc (copper phthalocyanine), and TNATA (4,4′,4″-tris-N-naphthyl-N-phenylamino-triphenylamine); said electron-blocking layer is made of a material selected from a group consisting of TPD (N,N′-diphenyl-N,N′-di(3-methylphenyl)-1,1′-.biphenyl-4,4′-diamine), BFE (poly(9,9-dioctylfluorene-co-N,N′-di(phenyl)-N,N′-di(3-carbo ethoxyphenyl)benzidine), NPB (4,4-bis[N-(1-naphthyl-1-)-N-phenyl-amino]-biphenyl), TPTE (N,N-diphenyl-N,N′-bis(di(3-methylphenyl)aminobiphenyl)benzidine), a polycarboxy-polymer, a quaternized polyamine-polymer, a polysulphato-polymer, a polysulpho-polymer, and a poly (vinylphosphonic acid). 
     
     
         12 . The mixed-type heterojunction thin-film solar cell structure according to  claim 8 , wherein when said inorganic wire array is a micron structure or a submicron structure, said inorganic wire array is made of a material selected from a group consisting of silicon, germanium, gallium arsenide, indium phosphide, gallium phosphide, antimony selenide, indium gallium nitride, a single element, a binary compound semiconductor, and a compound semiconductor containing more than two components. 
     
     
         13 . The mixed-type heterojunction thin-film solar cell structure according to  claim 8 , wherein said inorganic wire array has a total width of between 300 nm and 100 m on said substrate. 
     
     
         14 . The mixed-type heterojunction thin-film solar cell structure according to  claim 1 , wherein said conjugate polymer layer has a thickness of between 30 nm and 5 μm. 
     
     
         15 . The mixed-type heterojunction thin-film solar cell structure according to  claim 8 , wherein each wire of said inorganic wire array has a length of between 50 nm and 50 μm. 
     
     
         16 . The mixed-type heterojunction thin-film solar cell structure according to  claim 8 , wherein when said inorganic wire array is a nanometric structure, a section, which is vertical to said substrate, of each wire has a width of between 5 nm and 300 nm; when said inorganic wire array is a micron structure, a section, which is vertical to said substrate, of each wire has a width of between 300 nm and 3000 μm. 
     
     
         17 . The mixed-type heterojunction thin-film solar cell structure according to  claim 8 , wherein when said inorganic wire array is a micron structure or a submicron structure, spacing between two wires is below 100 μm; when said inorganic wire array is a nanometric structure, spacing between two wires is below 50 times width of a wire. 
     
     
         18 . The mixed-type heterojunction thin-film solar cell structure according to  claim 8 , wherein when said inorganic wire array is a nanometric structure, a depth by which wires of said inorganic wire array is inserted into said conjugate polymer layer is between 30 nm and 5 μm.