Boosting Infrared Light Harvesting by Molecular Functionalization of Metal Oxide/Polymer Interfaces in Efficient Hybrid Solar Cells

Journal article

Hybrid solar cells based on light absorbing semiconducting polymers infiltrated in nanocrystalline TiO 2 electrodes, have emerged as an attractive concept, combining benefits of both low material and processing costs with well controlled nano-scale morphology. However, after over ten years of research effort, power conversion efficiencies remain around 0.5%. Here, a spectroscopic and device based investigation is presented, which leads to a new optimization route where by functionalization of the TiO 2 surface with a molecular electron acceptor promotes photoinduced electron transfer from a low-band gap polymer(poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4- b0]dithiophene)-alt-4,7-(2,1,3-benzothiadia-zole)] (PCPDTBT) to the metal oxide. This boosts the infrared response and the power conversion efficiency to over 1%. As a further step, by "co-functionalizing" the TiO 2 surface with the electron acceptor and an organic dye-sensitizer, panchromatic spectral photoresponse is achieved in the visible to near-IR region. This novel architecture at the heterojunction opens new material design possibilities and represents an exciting route forward for hybrid photovoltaics. Copyright © 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim.

Authors: Grancini, G; Kumar, R; Abrusci, A; Yip, H; Li, C

• Publication status: Published
• Journal: ADVANCED FUNCTIONAL MATERIALS
• Volume: 22
• Issue: 10
• Pages: 2160-2166
• Publication date: 2012-05-23
• DOI: 10.1002/adfm.201102360
• EISSN: 1616-3028
• ISSN: 1616-301X
• Language: English
• Keywords: ultrafast spectroscopy; spectral response; hybrid photovoltaic devices; low-band-gap polymer; polymer-metal oxide interfaces