Synthesis of polythiophene and semiconductor nanocomposite and application to solar cell material

• Main Authors: Ming-De Lu, 盧明德
• Other Authors: Sze-Ming Yang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/58801208469540394810

博士 === 國立中央大學 === 化學工程與材料工程研究所 === 96 === This thesis mainly contains three major parts. Including polythiophene-TiO2 nanocomposite, bilayer tubes of poly(3,4-ethylenedioxythiophene) (PEDOT) and titania, poly(3-hexylthiophene) (P3HT)/semiconductor nanorod nanocomposite and application to solar cell material were described in thesis. The use of nanorod (or nanotube) result is demonstrated significantly to improve device performance, and that these improvements are caused partially by lower charge recombination, facilitating the electron transport. A major advantage of nanorod (or nanotube) as electron acceptors is their capability to generate continuous pathway, nanorod (or nanotube) structures so that a direct and ordered path for photogenerated electrons reaching the collecting electrode. First part: A composite of polythiophene and TiO2 nanotubes was synthesized. The XPS spectra of the composites show that the Ti2p peak shifts to a lower binding energy and S2p peak shifts to a higher binding energy. The TGA results also show that phase segregation occurred when the nanocomposites contained 35 % polythiophene. A P3HT composite, grafted on TiO2 nanotubes, was synthesized. Photoluminescence (PL) measurements show that the emission intensity of P3HT mixed with TiO2 nanotubes was one third of that of random P3HT, while that of P3HT grafted onto TiO2 nanotubes was 10%. The results show that the P3HT grafted onto TiO2 nanotubes is more efficient in photoinduced charge transfer than a physical mixture of P3HT and TiO2 nanotubes, indicating this composite has potential for the fabricating hybrid organic-inorganic solid state solar cells. A nanocomposite of PEDOT and titania nanotube was synthesized, a silane containing a thiol group, (3-mercaptopropyl)trimethoxysilane was grafted on the surface of titania nanotube. AuCl4- then formed a self-assembled monolayer on the grafted nanotube. EDOT was used in situ polymerized by AuCl4-. TEM photographs show the TiO2 nanotube and PEDOT nanocomposite shows nanotube structure. The XPS and EDS results showed the nanocomposite contains gold. Second part: Synthesis of bilayer tubes of PEDOT and TiO2 by electrochemical polymerization of PEDOT and chemical deposition of TiO2 in the pores of anodic alumina was reported. SEM photographs show the tubes of uniform diameters around 200 nm. TEM photographs confirm the formation of TiO2 and PEDOT bilayer tubes of 230 nm and 100 nm diameter, the thickness of outside TiO2 layer and inner PEDOT layer are around 20 nm under the experimental condition. The XPS spectra of the bilayer tubes show that the Ti2p peak shifts to a lower binding energy and S2p peak shifts to a higher binding energy. Electron diffraction patterns show that TiO2 nanotubes formed was single crystals of anatase phase. Third part: The synthesis of semiconductor oxide nanorod, including TiO2 and ZnO were synthesized, TiO2 nanorods are prepared using the template method, involving the synthesis of TiO2 nanorods in the nanoholes of the membrane, involving the synthesis of TiO2 nanorods in the nanoholes of the membrane. ZnO rod arrays have been successfully synthesized on ITO glass substrate from the aqueous solution of Zn(NO3)2 and C6H12N4 (HMT). The PL quenching measurements reveal that the photo-induced electron transfer is more efficient in P3HT/TiO2 (or ZnO) nanorods than in the P3HT/TiO2 (or ZnO) nanoparticle film. The photovoltaic cells that are made from P3HT/TiO2 nanorod array have much higher power conversion efficiency than those made from P3HT/TiO2 nanoparticles. The photovoltaic cells that are made from P3HT/ZnO nanorod array have much higher Isc and Voc than those made from P3HT/ZnO nanoparticles.