HOPV12 - Blogs

4 th Hybrid and Organic Photovoltaic Conference -Uppsala 2012 69
B28 - Charge Transport in a Novel Mesoporous TiO2 Semiconductor
Edward Crossland, Henry Snaith
University of Oxford, Clarendon Laboratory, Parks rd, Oxford, GB
Mesoporous inorganic semiconducting layers lie at the heart of many promising hybrid
photovoltaic device concepts. The mesoscale pore size and morphology of the inorganic phase
are critical for achieving a high specific surface semiconductor heterojunction for efficient
charge generation. Transport of charge within the inorganic phase, on the other hand, is
limited by a high density of electronic defect states that depend on atomic scale order – i.e.
crystal domain size. Using the classic route of thermally sintering of pre-formed nanocrystals,
the increase in exposed surface achieved by decreasing particle size is necessarily
accompanied by an increase in the number and frequency of inter-particle grain boundaries.
Macromolecular self-assembly of structure-directing agents and porous templates are routes
to pattern mesoporous ceramics that decouple atomic from mesoscale order and offer the
possibility of extending crystallinity far beyond the characteristic pore dimension.
This goal of this concept is to produce materials combining rapid charge transport with high
exposed surface and to disentangle how surface states vs. grain boundaries influence charge
transport. We present the synthesis and characterisation of an exciting new class of
mesoporous TiO2 semiconductor and use transient photocurrent and photovoltage decay to
probe charge transport properties in model solid-state and liquid electrolyte DSC devices.
© SEFIN 2012