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Proceedings Paper

Solid state solar cell made from nanocrystalline TiO2 with a fluorene-thiophene copolymer as a hole conductor
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Paper Abstract

We study the charge recombination kinetics and photovoltaic performance of composites of poly (9,9-dioctylfluorene-co-bithiophene) polymer with nanocrystalline TiO2. Transient optical spectroscopy confirms that photoexcitation of the polymer leads to electron transfer to the TiO2 and indicates that charge recombination is slow with a half-time of 100 μs to 10ms. Polymer penetration into thick porous TiO2 layers is improved by melt-processing and treatment of the TiO2 surface. We study the photovoltaic characteristics of devices with different layer thickness and interface morphology. Quantum efficiency (QE) of all devices is increased by reducing the TiO2 and polymer layer thickness. Inserting a thin porous TiO2 layer in to a thin bi-layer device increases the QE by a factor of five. The improved device shows peak QE and monochromatic power conversion efficiencies of over 11% and 1% at 440nm respectively. The device produced a short-circuit current density of 300μAcm-2, a fill factor of 0.24 and an open-circuit voltage of 0.8V under AM1.5 illumination. The fill factor is increased from 0.24 to 0.40 by introducing an additional dip-coating layer and overall power conversion efficiency is increased by 50%. However, the device produced degraded current-voltage characteristics. We investigate this using an alternative polymers and different top contact metals.

Paper Details

Date Published: 6 February 2004
PDF: 11 pages
Proc. SPIE 5215, Organic Photovoltaics IV, (6 February 2004); doi: 10.1117/12.506017
Show Author Affiliations
Punniamoorthy Ravirajan, Imperial College London (United Kingdom)
Univ. of Jaffna (Sri Lanka)
Saif A Haque, Imperial College London (United Kingdom)
Dmitry Poplavskyy, Imperial College London (United Kingdom)
James R. Durrant, Imperial College London (United Kingdom)
Donal D. C. Bradley, Imperial College London (United Kingdom)
Jenny Nelson, Imperial College London (United Kingdom)

Published in SPIE Proceedings Vol. 5215:
Organic Photovoltaics IV
Zakya H. Kafafi; Paul A. Lane, Editor(s)

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