Title: Understanding charge transport and recombination in dye-sensitized solar cells using an experimentally validated coupled optical and electrical model
Authors : Wenger, Sophie
Schmid, Matthias
Rothenberger, Guido
Grätzel, Michael
Schumacher, Jürgen
Conference details: MRS Spring Meeting, San Francisco, USA, 5 - 9 April 2010
Publisher / Ed. Institution : Material Research Society (MRS)
Issue Date: Apr-2010
License (according to publishing contract) : Licence according to publishing contract
Type of review: Not specified
Language : English
Subjects : Dye sensitized solar cell; Characterization; Modelling
Subject (DDC) : 540: Chemistry
621.3: Electrical engineering and electronics
Abstract: The mathematical description of charge transport and recombination in dye-sensitized solar cells requires equations specific to nanostructured electrochemical devices. Charge transport in the mesoporous TiO2 film is generally assumed to be purely diffusive (no drift component) due to the high ionic strength of the electrolyte permeating the pores. Experiments have repeatedly shown electron lifetimes in the ms range, which depend on illumination intensity, suggesting a trapping-limited transport. The electron diffusion length is in the order of the TiO2 film thickness (~10 μm) which induces a photovoltage of about 0.8 V under full sun illumination. We have previously developed a validated optical model based on coherent and incoherent optics to accurately calculate the charge generation function in a complete device. The optical model is coupled to a linear electrical transport model via the charge generation function as source term. From the analytical solution, one can calculate the steady-state behavior, e.g. I-V curves. This paper presents our next steps in developing a spatially resolved time-dependent model to calculate the response of the cell to small perturbations (e.g. illumination or applied potential). Here, the trap distribution and the electron recombination route via the TiO2 conduction band and possibly via surface states come into play. From the numerical solution of this extended model one can extract electron lifetimes and electron diffusion coefficients from time-dependent measurements and further simulate the parameters for any defined experimental condition, e.g. at the maximum power point.
Departement: School of Engineering
Organisational Unit: Institute of Computational Physics (ICP)
Publication type: Conference Other
URI: https://digitalcollection.zhaw.ch/handle/11475/11670
Appears in Collections:Publikationen School of Engineering

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