Designs of solar voltaic cells based on carbon nano-tubes II

Abstract

Inspired by Asian rice-paddy and Firefighter spiraling steps staircase, we employ a nano-manipulator augmented with CAD as a nano-robot water-buffalo, promised to improve by an order of the magnitude the pioneer work of GE Solar voltaic cell (SVC) made of one Carbon NanoTube (CNT) enjoyed QE_CNT~5%. Our CNT was made of the semiconductor at NIR wavelength E_BG= 1.107 eV which can absorb any photon whose wavelength λ ≤ λ_NIR =1.11 μm. This EBG is chosen due to the cutoff of Pb-Crown glass which happened put us in the equal amount of solar energy spectrum as silicon p-n junction SVC. Nevertheless, the exceeding of the Shockley and Queisser efficiency limit 30% might be due to the fact that we have much compact one-dimensional building block CNT of a tiny diameter 0.66 nm. It allows us to construct 3D structure, called volume pixel, "voxel," in a much efficient spiraling steps staircase fashion to capture the solar spectral energy spreading naturally by a simple focusing lens without occlusion. For real-estate premium applications, in Space or Ocean, we designed a volume pixel (Voxel) housing a stack of 16 CNTs steps spiraling 22° each like the fire house staircase occupying the height of 16 x d_CNT =16 x 0.66nm= 10.56 nm and covering over 360°. The total SVC had the size 2x2 meter², consisting of 100×100 lenslet array. Each lens was made of Pb-Crown glass which was inexpensive simple spherical lens having the diameter of D_lens=2 cm and F#=0.7. It can focus the sunlight a millionth times stronger in a smallest possible focal spot size, λ_Yellow=0.635 μm< λ_{Max photons} <λ_Red=0.73 μm, where the largest number of solar photons, 68%, according to the Plank radiation spectrum at 6000°K and the Lord Rayleigh diffraction limit. The solar panel seals individually such an array of 3D cavities of SVC enjoying theoretically from the UV 12% (wasted in passing through) visible 68% to the infrared 20% at a total of 16x5%~80% total QECNT per cell. The solar panel is made of light-weight carbon composite tolerating about 20% inactive fill factor and 10% dead pixels.