Polymer-Nanoparticle Hybrid Photovoltaic Research for U.S. Air Force Applications
Final rept. 18 May 2007-17 May 2009
NATIONAL TAIWAN UNIV TAIPEI (TAIWAN) DEPT OF MATERIALS SCIENCE AND ENGINEERING
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The polymer photovoltaic devices based on the poly3-hexylthiopheneTiO2 nanorods hybrid material P3HTTiO2 has better thermal stability than that of P3HTPCBM hybrid material. We have investigated the effect of polymer molecular weight on the morphology and performance of P3HTTiO2 nanorod hybrid photovoltaic devices by using scanning near field optical microscopy SNOM, atomic force microscopy AFM and confocal Raman microscopy. The results provide a direct observation of the correlation between the nanoscale absorption, morphology and device performance. An enhancement in the device performance can be achieved by removing or replacing the insulating surfactant on the TiO2 nanorods surface with a more conductive ligand, which can play the role to assist charge separation efficiency or also to prevent from back recombination, giving a large improvement in the short circuit current and fill factor. The F-doped TiO2 nanocrystal has increased the carrier concentration, conductivity and charge separation efficiency of the hybrid that results improved power conversion efficiency. A novel series of soluble alternating conjugated copolymers, comprised of 9,9-dihexylfluorene and cyclopentadithiophenes P1-P5, were synthesized via Pd-catalyzed Suzuki coupling reaction in good yields. The P2 and P3 with electron donating non-pi-substituents ethylenedioxy and propylenedioxy bridges the 3,3 positions of the thiophene groups display high fluorescence quantum yields and red-shifted absorption as compared with non substituted P1. However, the P4 and P5 are weakly fluorescent and exhibit blue-shifted absorption which are due to the presence of electron-withdrawing pi-substituents carbonyl and dicyanoethenyl. Their applications in the photovoltaic device are current under investigation.
- Polymer Chemistry
- Electrooptical and Optoelectronic Devices