Abstract:
The present invention is a photosensitized electrode which absorbs sun light to obtain pairs of separated electron and hole. The photosensitized electrode is fabricated with simple procedure and has low cost. The electrode has excellent chemical resistance and is fitted to be applied in a solar cell device with enhanced sun-light absorbing ability. The present invention can be applied in an optoelectronic device or a hydrogen generator device too.

Description:
FIELD OF THE INVENTION  
       [0001]    The present invention relates to an photosensitized electrode; more particularly, relates to obtaining a photosensitized electrode having an indium nitride (InN) photosensitive layer to be applied in a solar cell device, an optoelectronic device and a hydrogen generator device. 
       DESCRIPTION OF THE RELATED ARTS  
       [0002]    During recent years, a nano-crystal film technology is utilized in a Dye-Sensitized Solar Cell (DSSC) so that the efficiency of photoelectrical transformation has gained a great improvement along with a cheap cost. Hence, the cost for a solar cell may quite possibly drop for about 1/10 to ⅕. The former DSSC basically uses smooth electrode; and its dye molecule layer (such as a ruthenium ligand series, a cyanine, a chlorophyll or a dye derived) transforms electric charge effectively only at a monolayer close to the semiconductor. Because a smooth electrode has small area for absorption with little absorbing ability, its photoelectrical transformation ability is low (less than 1%). Recently, a porous nano-structured electrode is introduced for solving this problem. Because the surface area of the catalyst is thousands times of that of the smooth electrode, the photo electrical transformation ability is greatly improved. According to Michael Graetzel&#39;s research, the photoelectrical transformation efficiency of the DSSC is notably improved to 8%. 
         [0003]    The DSSC obviously relies its efficiency on its nanoelectrode structure of titanium oxide (TiO 2 ). Therefore, on fabricating the TiO 2 , the shape, the arrangement and the interface characteristic of nano-crystal has to be well-controlled. The inner surface area of the TiO 2  decides how much dye will be kept; the distribution of the holes affects the spreading of the redox pairs; the distribution of the granular size affects its optical characteristics; and the electron flow determines the connection between the particles. Nowadays, a TiO 2  electrode has a electron transferring rate of 10 4  cm 2 /s; so the electrons are easy to be re-combined to the dye for an reaction. 
         [0004]    Under a best experimental environment with a best dye, Graetzel, etc. make the transformation efficiency arrive at 10% which is quite close to that of a non-crystal system of 9%-10%; yet still worse than that of the multi-crystal system of 15%. And, as what is noteworthy, the costs for an organic dye/TiO 2  and a multi-crystal system are so high that their costs are still uncompetitive to that of petroleum fuel, like oil or gas. 
         [0005]    A prior art is revealed in Taiwan, called “A solar cell unit and a module thereof”, comprising an optoelectronic transformation layer with an upper and an lower surface; an anode layer obtained on the upper surface, comprising an anode conductive part extending out of the brim of the optoelectronic transformation layer; a cathode obtained on the lower surface, comprising a cathode conductive part extending out of the brim of the optoelectronic transformation layer; and more than one separating part set at the brim of the optoelectronic transformation layer, where the anode conductive part and the cathode conductive part is further extended out of the separating part; the optoelectronic transformation layer comprises a dye photosensitive layer and an electrolyte; the dye photosensitive layer is deposed on the a node layer; and the electrolyte is filled fully between the anode layer and the cathode layer. 
         [0006]    Although the above DSSC has a great improvement in transformation ability, the cost is high and the fabricating procedure is complex that some elements in the environment has to be controlled, such as the granular size of the TiO 2  and the distribution of the particles. Besides, after the prior art of “A solar cell unit and a module thereof” is shone under the sun for a long time, the material may have a qualitative change to lose its photosensitivity with lifetime shortened. Hence, the prior arts do not fulfill users&#39; requests on actual use. 
       SUMMARY OF THE INVENTION  
       [0007]    The main purpose of the present invention is to fabricating a photosensitized electrode with low cost and with long lifetime to be applied in a solar cell device having enhanced absorbing ability. 
         [0008]    To achieve the above purpose, the present invention is an InN TiO 2  photosensitized electrode, comprising a substrate, a TiO 2  film and an InN photosensitive layer, where a fabrication method for the photosensitized electrode comprises placing a substrate, coated with a TiO 2  film, in a reaction chamber; introducing hydrazoic acid (HN 3 ) and a compound containing indium into the reaction chamber; illuminating the InP photosensitive layer with an ultraviolet light; and obtaining an InN photosensitive layer on the TiO 2  film. Accordingly, a novel InN/TiO 2  photosensitized electrode is obtained. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0009]    The present invention will be better understood from the following detailed description of the preferred embodiment according to the present invention, taken in conjunction with the accompanying drawings, in which 
           [0010]      FIG. 1  is a structural view showing a preferred embodiment according to the present invention; 
           [0011]      FIG. 2  is a flow view showing the fabricating of the photosensitized electrode; 
           [0012]      FIG. 2A ,  FIG. 2B ,  FIG. 2C  and  FIG. 2D  are views showing step (a), step (b), step (c), and step (d) for fabricating the photosensitized electrode, respectively; and 
           [0013]      FIG. 3  is a view showing a state of use of the electrode. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0014]    The following description of the preferred embodiment is provided to understand the features and the structures of the present invention. 
         [0015]    Please refer to  FIG. 1 , which is a structural view showing a preferred embodiment according to the present invention. As shown in the figure, the present invention is an InN(indium nitride)/TiO 2  (titanium oxide) photosensitized electrode  1 , comprising a substrate  11 , a TiO 2  film  12  and an InN photosensitive layer  13 . 
         [0016]    The substrate  11  is an indium tin oxide (ITO) glass, an fluorine tin oxide (FTO) glass or other transparent conductive substrate. 
         [0017]    The TiO 2  film  12  is covered on the substrate  11 . The TiO 2  film  12  has a nanoparticle structure, where a plurality of nanoparticles are evenly distributed in the TiO 2  film  12 , and where each nanoparticle has a diameter between 7 nm (nanometer) and 50 nm. The TiO 2  film  12  has a thickness between 100 nm and 100000 nm and is made of a metal oxide having a high band-gap. 
         [0018]    The InN photosensitive layer  13  is made through a chemical vapor deposition (CVD), a physical vapor deposition (PVD) or other epitaxial film growth method. The InN photosensitive layer  13  is coated on the TiO 2  film  12 . The InN photosensitive layer  132  has a thickness between 1 nm and 10000 nm. Thus, with the above structure, a novel photosensitized electrode is obtained. 
         [0019]    When a light penetrates through the substrate  11  of the photosensitized electrode  1  into the photosensitive layer  13 , an electron is injected into the TiO 2  film  12  from the InN photosensitive layer  13  and then the electron is conducted to an outside circuit from the substrate, where the InN photosensitive layer  13  absorbs an optical wavelength between 390 nm and 800 nm. 
         [0020]    Please refer to  FIG. 2  and  FIG. 2A  until  FIG. 2D , which are a flow view showing the fabricating of the photosensitized electrode and views showing step (a) until step (d) of the fabricating of the photosensitized electrode. As shown in the figures, the fabricating of the photosensitized electrode according to the present invention comprises the following steps: 
         [0021]    Step (a): A substrate  11  coated with a TiO 2  film  12  is placed into a reaction chamber  2 , where the TiO 2  film  12  is coated on the substrate  11  through a CVD or a PCD. 
         [0022]    Step (b): A hydrazoic acid (HN3)  31  and a compound containing indium  32  is introduced into the reaction chamber  2 , where the ratio of HN3  31  to the compound containing indium  32  is between 1 and 10. The compound containing indium  32  is a trimethylindium, a triethylindium, a indium-containing metallo-organic precursor or a combination of indium-containing metallo-organic precursors. The present invention uses the HN3  31  and the compound containing indium  32  as precursors; and the HN3  31  can be replaced with a compound containing nitrogen. 
         [0023]    Step (c) The substrate  11  is then illuminated with an ultraviolet (UV) light, where the UV light is obtained from a continuous UV lamp, an excimer laser, a semiconductor laser, a gas laser, a solid-state laser, a liquid laser, a chemical laser or a free-electron laser, and where the TiO2 film  12  bears a temperature between 600° C. (Celsius degree) and 900° C. 
         [0024]    Step (d): An InN photosensitive layer  13  is obtained on the TiO 2  film  12 . Thus, an InN photosensitized electrode  13  is obtained through the above steps, where the total process time is between 1 hr and 8 hr. 
         [0025]    Please refer to  FIG. 3 , which is a view showing a state of use of the electrode. As shown in the figure, the photosensitized electrode  1  according to the present invention is assembled with a platinum counter electrode  51  to form a solar cell device filled with an electrolyte  52  inside. The present invention can be applied to a solar cell device, a photovoltaic device, a hydrogen generation devices and an optoelectronic device. 
         [0026]    To sum up, the present invention is an InN/TiO2 photosensitized electrode, where a lifetime issue of the dye for a Dye-Sensitized Solar Cell (DSSC) is solved; an optical absorption efficiency is enhanced; a production procedure is simplified; and a production cost is reduced. 
         [0027]    The preferred embodiment herein disclosed is not intended to unnecessarily limit the scope of the invention. Therefore, simple modifications or variations belonging to the equivalent of the scope of the claims and the instructions disclosed herein for a patent are all within the scope of the present invention.