3D Defected Carbon Nano-Tube Dye-Sensitive Solar Cell

1. Objective

Since the pioneering work of Groatzel’s group, where an overall efficiency of 10% has been demonstrated, dye-sensitized solar cells (DSSCs) have been established as reliable alternatives to classical photovoltaics. In order to pursue optimized performance of solar cell, we propose a new DSSC structure which integrates a novel concept and fabricating techniques using “defected” CNT and TiO2 nanotubes. Besides utilizing inherent advantages of these materials, high performance nano-materials are printed and grown in a three dimensional grating pattern array for the purpose of capturing every useful incident photons. By combining the material property and physical structure benefits of a DSSC cell, we will be able to maximize the efficiency of this novel DSSC solar cell.

2. Research Motivation and Plan

3D structure in grating pattern for DSSC:
Conventional flat solar cells reflect a significant portion of the light that strikes them, reducing the amount of energy they absorb. The new DSSC structure we proposed is the 3D grating pattern array which trap and absorb light received from many different angles so that the cells remain efficient even when the sun is not directly overhead. With optimized height and spacing of this 3D structure, reflections off 3D structure would provide more opportunity for each photon of sunlight to interact with photoelectron material and make every incident phones functional. This structure would increase the power output from PV cells of a given size, or allow cells to be made smaller while producing the same amount of power. That could allow them to be used on projects which require light-weight structure such as spacecraft without the mechanical aiming systems that maintain a constant orientation to the sun.

Advanced lithography tool and simulation software which are widely used in VLSI fabrication provides promising and reliable methods of pattern design and printing. 3D pattern will be constructed by defected CNT covered by TiO2 nanotubes and this forms the essential structure of DSSCs. Conventional nanocrystalline TiO2 shows photovotaically optimized thickness is about 15um which is unfavorable to our 3D design. In order to maintain spacing and height without being filled up by nano-crystalline TiO2, TiO2 nanotube with its high degree of controllable orientation becomes an alternative candidate of photoelectron material in our novel nanotube DCCS.

Defected carbon nano tube and TiO2 nanotube in 3D pattern:
Advantages such as flexibility, electrical conductivity, chemical stability and electrochemically activity make carbon nanotube an ideal candidate for researchers who are pursuing optimized design of solar cell. In order to replace the oxide and platinum in DSSCs, a single layer need to be transparent, to conduct electricity, and to be a catalyst for the electricity-producing reaction. However, ordinary nanotube films are not particularly good in performing both functions. Previous theory had suggested that materials may function better as catalysts when they have tiny defects, providing sites for chemicals to attach. In this project we are aiming at developing the technique to fabricate defected CNT in 3D pattern and characterizing those influences from 3D structure and defects on CNT electrochemistry property. Furthermore, the integration of fabrication process of CNT and TiO2 nanotubes will be our essential topic in the second phase of our research work.

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