The research for new material of solar cell with chlorophyll

• Main Authors: Bin-Huang Yang, 楊秉晃
• Other Authors: 廖重賓
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/52qer5

碩士 === 國立虎尾科技大學 === 光電與材料科技研究所 === 98 === The highly efficient system for harvesting light energy within plants is called the photosystem. It is mainly composed of ubiquitous chlorophyll molecules. When a light ray is incident on a plant, it is most likely caught by the antenna chlorophylls within this photosystem and then guided into the reaction center which performs the oxidation-reduction reaction to produce essential nutrients for maintaining the life of plant. This whole process is known to be the photosynthesis. At the above reaction center, the light is forced to cause the emergence of an electron-positron pair. With the electron being transfered from the chlorophyll to the pheophytin, a difference in oxidation-reduction potenials among the two is then established . All this process typically takes about 10-12 seconds. This current research aims to employ part of the above process for the making of organic solar cells in our favor. Nowadays, the best efficiency of practical GaAs solar cell is around 40 %。 In contrast, the light-trapping efficiency of chlorophyll molecules within the photosystem is above 90%. Further, there are abundant chlorophylls ready for novel possibilities of organic solar cells. The highly efficient system for harvesting light energy within plants is called the photosystem. It is mainly composed of ubiquitous chlorophyll molecules. When a light ray is incident on a plant, it is most likely caught by the antenna chlorophylls within this photosystem and then guided into the reaction center which performs the oxidation-reduction reaction to produce essential nutrients for maintaining the life of plant. This whole process is known to be the photosynthesis. At the above reaction center, the light is forced to cause the emergence of an electron-positron pair. With the electron being transfered from the chlorophyll to the pheophytin, a difference in oxidation-reduction potenials among the two is then established . All this process typically takes about 10-12 seconds. This current research aims to employ part of the above process for the making of organic solar cells in our favor. Nowadays, the best efficiency of practical GaAs solar cell is around 40 %。 In contrast, the light-trapping efficiency of chlorophyll molecules within the photosystem is above 90%. Further, there are abundant chlorophylls ready for novel possibilities of organic solar cells. First-principle quantum mechanical codes were employed to simulate the potential difference between a chlorophyll and a pheophytin in various structures. It was revealed that when the chlorophyll was used as the anode and pheophytin as the cathode, a voltage difference of 9.4V could be established. Note that, under the AM 1.5 condition, the solar power irradiation is roughly 100 mW/cm2. Experiments on simple hand-made organic batteries were launched, using extracted chlorophyll and pheophytin solutions, salt bridge and voltage meter. The best result so far is an organic cell of about 0.8V in open voltage 1mA in short-circuit current in the area 16 cm2, giving an average efficiency of about 0.07%。