Photovoltaic & Optoelectronic Device Group

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Enhancement of charge-transport characteristics in polymeric films using polymer brushes.

Nano Lett 6:3 (2006) 573-578

Authors:

Gregory L Whiting, Henry J Snaith, Saghar Khodabakhsh, Jens W Andreasen, Dag W Breiby, Martin M Nielsen, Neil C Greenham, Richard H Friend, Wilhelm TS Huck

Abstract:

We show that charge-transporting polymer chains in the brush conformation can be synthesized from a variety of substrates of interest, displaying a high degree of stretching and showing up to a 3 orders of magnitude increase in current density normal to the substrate as compared with a spin-coated film. These nanostructured polymeric films may prove to be suitable for electronic devices based on molecular semiconductors as current fabrication techniques often provide little control over film structure.

Ion‐Coordinating Sensitizer in Solid‐State Hybrid Solar Cells

Angewandte Chemie Wiley 117:39 (2005) 6571-6575

Authors:

Henry J Snaith, M Zakeeruddin, Lukas Schmidt‐Mende, Cédric Klein, Michael Grätzel

Ion-Coordinating Sensitizer in Solid-State Hybrid Solar Cells

Angewandte Chemie - International Edition 44:39 (2005) 6413–6417

Authors:

HJ Snaith, S. M. Zakeeruddin, L. Schmidt-Mende, C. Klein

Self-Organization of Nanocrystals in Polymer Brushes. Application in Heterojunction Photovoltaic Diodes

Nano Letters 5:9 (2005) 1653-1657

Authors:

HJ Snaith, G. L. Whiting, B. K. Sun, N. C. Greenham

Morphological and electronic consequences of modifications to the polymer anode 'PEDOT:PSS'

Polymer 46:8 (2005) 2573-2578

Authors:

HJ Snaith, H Kenrick, M Chiesa, RH Friend

Abstract:

We present a microscopic and electronic investigation of the polymeric anode poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) used as an electrode in photovoltaic and single carrier diodes. PEDOT:PSS is processed from aqueous solution as a colloidal dispersion with excess PSS present. We modify the PEDOT:PSS solution by the addition of a high boiling point alcohol, glycerol, which is known to increase the conductivity of the spin-coated film. Atomic force microscopy indicates swelling and greater aggregation of the PEDOT-rich colloidal particles found in this system. Current-voltage characteristics of 'hole-transporting' diodes, formed with gold contacts, suggest less surface enrichment of PSS in the glycerol modified electrode. Through Kelvin probe microscopy, we find the surface potential of glycerol modified PEDOT:PSS decreases by approximately 0.12 eV, which we assign to a reduction in surface enrichment by PSS. Photovoltaic diodes, using a PFB:F8BT polymer blend as the photo-active layer, and glycerol modified PEDOT:PSS anodes are significantly improved as compared to those with unmodified PEDOT:PSS anodes. This is likely to be due to improved hole-injection from the active polymer film into the PEDOT:PSS anode. This emphasises the electronic consequences of the morphological reorientation of the PEDOT and PSS. © 2005 Published by Elsevier Ltd.