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Infiltration of Regioregular Poly[2,2′‐(3‐hexylthiopene)] into Random Nanocrystalline TiO 2 Networks
Author(s) -
Bartholomew G. P.,
Heeger A. J.
Publication year - 2005
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200400277
Subject(s) - materials science , nanocrystalline material , polymer , nanoporous , crystallite , chemical engineering , overlayer , composite material , nanotechnology , chemistry , metallurgy , engineering
Polymer infiltration into random nanocrystalline TiO 2 networks is examined using a combination of imaging, surface analysis, and depth‐profiling techniques. Nanocrystalline TiO 2 network substrates were fabricated by established methods; the resulting networks were examined using scanning electron microscopy and found to be typical of those reported in the literature. Regioregular poly[2,2′‐(3‐hexylthiopene)] (rrP3HT) was drop‐cast from solution onto the TiO 2 ‐network substrates. Infiltration of the polymer into the nanoporous TiO 2 network was determined by monitoring the ratio of carbon‐ion signal—by means of secondary‐ion mass spectrometry from a top overlayer of rrP3HT—to the carbon signal from the same polymer within the TiO 2 network. A very low incorporation of polymer was found (0.5 %), even for highly porous (≈ 65 %) networks. Several strategies were used to increase the degree of polymer infiltration, including heat treatment, surface derivatization, and the use of low‐molecular‐weight fractions. A high of 22 % rrP3HT as a percentage of the total volume of a random nanocrystalline film is reported. Previous results for hybrid rrP3HT/random nanocrystalline TiO 2 network devices are examined and analyzed in the context of these findings.