Ultrafast spectroscopy and characterization of organic photovoltaic with different morphology

• Main Author: Tai, Kong Fai
• Other Authors: Huan Cheng Hon, Alfred
• Format: Final Year Project
• Language: English
• Published: 2011
• Subjects: DRNTU::Science
• Online Access: http://hdl.handle.net/10356/44222
• Institution: Nanyang Technological University

Poly(3-hexylthiophene) (P3HT) and fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) has been extensively studied over the decade, with a solar conversion efficiency approaching 5 %. The structural morphology, ultrafast carrier dynamics and the cell performance are inter-related to each other. A slight difference on the morphology could affect the performance drastically. In this work, morphological characterization and optical characterization of as-spun film, thermal-annealed film, and nanofiber system were investigated and relate to each other. Nanofiber system has the largest portion of crystalline domain, but the ultrafast dynamics were found to be shorter-lived than the thermal-annealed system. In relation to the cell performance, thermal-annealed system shows the largest power conversion, followed by the nanofiber system, and as-spun system is the worst. Green processing technique is also important to help protect the environment while researching for clean energy alternatives. Water-soluble polymers that don’t require toxic organic solvent was studied in here also. Water-based polymer solar cell was fabricated in this work. Although self-ordering of the water-soluble polymers is not as pronounce as P3HT, a partially-water-based bi-layer device with PCBM as the acceptor shows an encouraging cell performance with 0.50 % efficiency, which was first reported in here. Possible reasons for the lower efficiency compare to organic-solvent based solar cell were stated in the end of this thesis. With more understanding on the water-based system, low-cost, environmental friendly processing of organic solar cell can be easily fabricated in ambient condition.