(a) Bare T-J solar cell. (b) With Si3N4 AR coating T-J solar cell. (c) ZnO nanotube T-J solar cell. Results and discussion
Figure 2a shows the top view of SEM images of the ZnO nanotube structure. The hydrothermal growth method depends on the polarity of the ZnO crystalline structure, which allows for self-alignment into a wurtzite shape. The C59 wnt structure of the ZnO nanotube arrays Selleck BIBF-1120 varied with the different diameters of the nanotubes (80 to100 nm). Figure 2b shows the energy dispersive spectrometer (EDS) image of a ZnO nanotube. It shows clearly the Zn and O elements on the cell. In a solar cell, the high performance of antireflection coating (AR coating) determines the efficiency. An AR coating on the top with a broadband low-reflectance characteristic is crucial for most solar cells. TEM was used to further investigate the microstructure of the as-synthesized ZnO nanorod arrays. Figure 3a shows a bright field TEM Aurora Kinase inhibitor image of a single ZnO nanotube. The diameter of the selected nanotube was uniform along the growth direction and was about 80 nm. The corresponding selected area electron diffraction (SAED) is shown in Figure 3b; it indicates that the nanotube grew along the  direction, the fastest growth direction of ZnO. A high-resolution
(HR) TEM image in Figure 3c shows the same result with the SAED pattern and indicates that the synthesized ZnO nanotube possessed a wurtzite single-crystal structure. Figure 3d shows an X-ray diffraction pattern of a ZnO nanotube grown on a T-J solar cell. triclocarban A strong (002) diffraction peak and various (101), (110), and (002) peaks can be observed. These results indicate that (002) is the main growth plane, which is perpendicular to the c-axis, and that the ZnO nanotube grew preferentially along the c-axis. Figure 2 SEM images and Energy dispersive spectrometer image of ZnO nanotubes. (a) Plan-view SEM images of the ZnO nanotube structure. (b) Energy dispersive spectrometer (EDS) image of ZnO nanotube. Figure 3 TEM image, SAED, high-resolution TEM image, and X-ray
diffraction pattern of ZnO nanotube. (a) TEM image of ZnO nanotube, (b) the corresponding SAED of the ZnO nanotube, (c) a high-resolution TEM image of the ZnO nanotube, and (d) X-ray diffraction pattern of ZnO nanotube grown on solar cell. Figure 4 shows the reflectance values of a bare T-J solar cell and T-J solar cells with Si3N4 and ZnO nanotube coating, respectively. Since the ZnO nanotube can suppress light scattering at short wavelengths, the T-J solar cell with a ZnO nanotube has the lowest reflectance, especially in the wavelength range of UV to green. The weighted reflectance of the ZnO nanotube is approximately 5.7% for the wavelength range of 300 to 1,800 nm, which is still lower than that of a cell with Si3N4 which is approximately 18.1%. The cell with a ZnO nanotube shows a lower optical reflectance for wavelength from 300 to 1800 nm.