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Title: An applied light-beam induced current study of dye-sensitised solar cells: Photocurrent uniformity mapping and true photoactive area evaluation

Abstract

The conditions for light-beam induced current (LBIC) measurement were experimentally optimised for dye-sensitised solar cells. The impacts of too fast a laser diode modulation frequency (f) and too short a dwell time (t{sub 0}) were investigated for their distortions, artefacts, and noise on the overall photocurrent map image. Optimised mapping conditions for fastest measurement were obtained at a f = 15 Hz and t{sub 0} = 900 ms. Whole device maps (nominal area 4 × 4 mm{sup 2}) were obtained on devices in which fabrication defects were intentionally induced. The defects were readily resolved with the LBIC setup and conditions. The inclusion of defects had the effect of broadening the photocurrent distribution and producing a sub-optimal tail to photocurrent histograms. Photoactive areas were derived from LBIC maps and were larger than those predicted by the projected screen printing pattern by up to 25%, which has obvious implications for efficiency measurements made on nominal projected active area.

Authors:
; ; ;  [1];  [1];  [2]
  1. CSIRO Energy Flagship, Mayfield West, NSW 2304 (Australia)
  2. (Australia)
Publication Date:
OSTI Identifier:
22308918
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 4; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BEAMS; CURRENTS; DEFECTS; DISTRIBUTION; DYES; EFFICIENCY; INCLUSIONS; LASER RADIATION; MODULATION; NOISE; SCREEN PRINTING; SOLAR CELLS; VISIBLE RADIATION

Citation Formats

Jones, Timothy W., E-mail: tim.jones@csiro.au, Anderson, Kenrick F., Duck, Benjamin C., Wilson, Gregory J., Feron, Krishna, and Centre for Organic Electronics, The University of Newcastle, Callaghan, NSW 2308. An applied light-beam induced current study of dye-sensitised solar cells: Photocurrent uniformity mapping and true photoactive area evaluation. United States: N. p., 2014. Web. doi:10.1063/1.4890935.
Jones, Timothy W., E-mail: tim.jones@csiro.au, Anderson, Kenrick F., Duck, Benjamin C., Wilson, Gregory J., Feron, Krishna, & Centre for Organic Electronics, The University of Newcastle, Callaghan, NSW 2308. An applied light-beam induced current study of dye-sensitised solar cells: Photocurrent uniformity mapping and true photoactive area evaluation. United States. doi:10.1063/1.4890935.
Jones, Timothy W., E-mail: tim.jones@csiro.au, Anderson, Kenrick F., Duck, Benjamin C., Wilson, Gregory J., Feron, Krishna, and Centre for Organic Electronics, The University of Newcastle, Callaghan, NSW 2308. Mon . "An applied light-beam induced current study of dye-sensitised solar cells: Photocurrent uniformity mapping and true photoactive area evaluation". United States. doi:10.1063/1.4890935.
@article{osti_22308918,
title = {An applied light-beam induced current study of dye-sensitised solar cells: Photocurrent uniformity mapping and true photoactive area evaluation},
author = {Jones, Timothy W., E-mail: tim.jones@csiro.au and Anderson, Kenrick F. and Duck, Benjamin C. and Wilson, Gregory J. and Feron, Krishna and Centre for Organic Electronics, The University of Newcastle, Callaghan, NSW 2308},
abstractNote = {The conditions for light-beam induced current (LBIC) measurement were experimentally optimised for dye-sensitised solar cells. The impacts of too fast a laser diode modulation frequency (f) and too short a dwell time (t{sub 0}) were investigated for their distortions, artefacts, and noise on the overall photocurrent map image. Optimised mapping conditions for fastest measurement were obtained at a f = 15 Hz and t{sub 0} = 900 ms. Whole device maps (nominal area 4 × 4 mm{sup 2}) were obtained on devices in which fabrication defects were intentionally induced. The defects were readily resolved with the LBIC setup and conditions. The inclusion of defects had the effect of broadening the photocurrent distribution and producing a sub-optimal tail to photocurrent histograms. Photoactive areas were derived from LBIC maps and were larger than those predicted by the projected screen printing pattern by up to 25%, which has obvious implications for efficiency measurements made on nominal projected active area.},
doi = {10.1063/1.4890935},
journal = {Journal of Applied Physics},
number = 4,
volume = 116,
place = {United States},
year = {Mon Jul 28 00:00:00 EDT 2014},
month = {Mon Jul 28 00:00:00 EDT 2014}
}
  • The charge recombination reaction from the semiconductor (TiO{sub 2}) conduction band to electron accepting electrolytes (I{sub 2}, I{sub 2}{sup -}, I{sub 3}{sup -}) in dye-sensitised solar cells is investigated theoretically. The non-adiabatic theory of electron transfer has been adapted to compute the charge transfer rate measured in different experimental settings (namely with and without external illumination). In both cases we are able to provide an atomic level description of the charge recombination to the electrolyte (CRE), which is in good agreement with the experimental data available. The model employs a detailed density-functional theory (DFT) description of the semiconductor-electrolyte interface andmore » the internal reorganization energy. A continuum dielectric model is used to evaluate the external component of the reorganization energy due to the solvent degrees of freedom. The intrinsic limitations of DFT are kept to a minimum by taking two key energetic parameters (the conduction band edge and the reaction energy) from the experiments. The proposed methodology correctly reproduces (i) the ratio between CRE rate to iodine and triiodide in dark, (ii) the absolute CRE rate to triiodide in dark, and (iii) the absolute CRE rate to I{sub 2}{sup -} under illumination.« less
  • Dye sensistised solar cell (DSC) based on nanocrystalline TiO{sub 2} has the potential to be used in indoor consumer power application. In realizing this, the DSC must be optimized to generate power under low lighting condition and under wider visible light range. The use of wide band dye N749 which has a wider spectrum sensitivity increases the photon conversion to electron between the visible light spectrums of 390nm to 700nm. This paper reports the study on the effectiveness of the dye solar cell with N749 dye under low light condition in generating usable power which can be used for indoormore » consumer application. The DSC was fabricated using fluorine doped tin oxide (FTO) glass with screen printing method and the deposited TiO{sub 2} film was sintered at 500°C. The TiO{sub 2} coated FTO glass was then soaked in the N749 dye, assembled into test cell, and tested under the standard test condition at irradiance of 1000 W/m{sup 2} with AM1.5 solar soaker. The use of the 43T mesh for the dual pass screen printing TiO{sub 2} paste gives a uniform TiO{sub 2} film layer of 16 µm. The low light condition was simulated using 1/3 filtered irradiance with the solar soaker. The fabricated DSC test cell with the N749 dye was found to have a higher efficiency of 6.491% under low light condition compared to the N719 dye. Under the standard test condition at 1 sun the N749 test cell efficiency is 4.55%. The increases in efficiency is attributed to the wider spectral capture of photon of the DSC with N749 dye. Furthermore, the use of N749 dye is more effective under low light condition as the V{sub OC} decrement is less significant compared to the latter.« less
  • Big data science informs energy research: large-scale screening of crystal structures identifies unforeseen class of dyes for dye-sensitised solar cells.
  • The role of electrical potential, charge transport, and recombination in determining the photopotential and photocurrent conversion efficiency (IPCE) of dye-sensitized nanocrystalline solar cells was studied. Electrostatic arguments and electrical impedance spectroscopy (EIS) are used to obtain information on the electrical and electrochemical potential distribution in the cell. It is shown that on the macroscopic level, no significant electrical potential drop exists within the porous TiO{sub 2} when it contacts the electrolyte and that the electrical potential drop at the transparent conducting oxide substrate (TCO)/TiO{sub 2} interface occurs over a narrow region, one or two layers of TiO{sub 2}. Analyses ofmore » EIS and other data indicate that both the photopotential of the cell and the decrease of the electrical potential drop across the TCO/TiO{sub 2} interface are caused by the buildup of photoinjected electrons in the TiO{sub 2} film. The time constants for the recombination and collection of the photoinjected electrons are measured by EIS and intensity-modulated photocurrent spectroscopy (IMPS). As the applied bias is varied from short-circuit to open-circuit conditions at 1 sun light intensity, recombination becomes faster, the collection of electrons becomes slower, and the IPCE decreases. The decrease of IPCE correlates directly with the decline of the charge-collection efficiency {eta}{sub cc}, which is obtained from the time constants for the recombination and collection of the photoinjected electrons. Significantly, at open circuit, {eta}{sub cc} is only 45% of its short-circuit value, indicating that the dye-sensitized nanocrystalline TiO{sub 2} solar cell behaves as a nonideal photodiode.« less
  • A solvent soaking and rinsing method, in which the solvent was allowed to soak all over the surface followed by a spinning for solvent draining, was found to produce perovskite layers with high uniformity on a centimeter scale and with much improved reliability. Besides the enhanced crystallinity and surface morphology due to the rinsing induced surface precipitation that constrains the grain growth underneath in the precursor films, large-area uniformity with film thickness determined exclusively by the rotational speed of rinsing spinning for solvent draining was observed. With chloroform as rinsing solvent, highly uniform and mirror-like perovskite layers of area asmore » large as 8 cm × 8 cm were produced and highly uniform planar perovskite solar cells with power conversion efficiency of 10.6 ± 0.2% as well as much prolonged lifetime were obtained. The high uniformity and reliability observed with this solvent soaking and rinsing method were ascribed to the low viscosity of chloroform as well as its feasibility of mixing with the solvent used in the precursor solution. Moreover, since the surface precipitation forms before the solvent draining, this solvent soaking and rinsing method may be adapted to spinless process and be compatible with large-area and continuous production. With the large-area uniformity and reliability for the resultant perovskite layers, this chloroform soaking and rinsing approach may thus be promising for the mass production and commercialization of large-area perovskite solar cells.« less