Photogeneration of charges in microcrystalline chlorophyll a

Hassan Kassi; Saïd Barazzouk; Marc Brullemans; Roger M. Leblanc; Surat Hotchandani

doi:10.1016/j.tsf.2010.04.002

Photogeneration of charges in microcrystalline chlorophyll a

Hassan Kassi, Saïd Barazzouk, Marc Brullemans, Roger M. Leblanc, Surat Hotchandani

Chemistry

Research output: Contribution to journal › Article › peer-review

5 Scopus citations

Abstract

The electric-field and temperature dependence of hole photogeneration in chlorophyll a (Chla) have been analyzed in terms of electric-field assisted thermal dissociation of charge pairs based on Onsager theory. An excellent agreement between the experimental and theoretical values of the slope-to-intercept ratio, S/I, for the plot of photogeneration efficiency vs. electric field at low field strengths provides a proof for the applicability of the Onsager approach to the photogeneration of charges in Chla. A value of 19 nm has been obtained for Coulomb capture radius, r_c, from S/I. From the temperature dependence of photogeneration, the initial separation, r ₀, of photogenerated electron-hole has been evaluated, and has a value of 1.24 nm. This smaller r₀ compared to r_c leads to a feeble dissociation probability of electron-hole pairs into free carriers, and may, among other factors, explain the low power conversion efficiencies of Chla photovoltaic cells.

Original language	English (US)
Pages (from-to)	5345-5348
Number of pages	4
Journal	Thin Solid Films
Volume	518
Issue number	18
DOIs	https://doi.org/10.1016/j.tsf.2010.04.002
State	Published - Jul 1 2010

Keywords

Electric field
Microcrystalline chlorophyll a
Onsager approach
Photocarrier generation
Time-of-flight technique

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Materials Chemistry
Metals and Alloys
Surfaces, Coatings and Films
Surfaces and Interfaces

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.tsf.2010.04.002

Cite this

@article{eff614be01e848c38d18485017851089,

title = "Photogeneration of charges in microcrystalline chlorophyll a",

abstract = "The electric-field and temperature dependence of hole photogeneration in chlorophyll a (Chla) have been analyzed in terms of electric-field assisted thermal dissociation of charge pairs based on Onsager theory. An excellent agreement between the experimental and theoretical values of the slope-to-intercept ratio, S/I, for the plot of photogeneration efficiency vs. electric field at low field strengths provides a proof for the applicability of the Onsager approach to the photogeneration of charges in Chla. A value of 19 nm has been obtained for Coulomb capture radius, rc, from S/I. From the temperature dependence of photogeneration, the initial separation, r 0, of photogenerated electron-hole has been evaluated, and has a value of 1.24 nm. This smaller r0 compared to rc leads to a feeble dissociation probability of electron-hole pairs into free carriers, and may, among other factors, explain the low power conversion efficiencies of Chla photovoltaic cells.",

keywords = "Electric field, Microcrystalline chlorophyll a, Onsager approach, Photocarrier generation, Time-of-flight technique",

author = "Hassan Kassi and Sa{\"i}d Barazzouk and Marc Brullemans and Leblanc, {Roger M.} and Surat Hotchandani",

note = "Funding Information: We would like to thank Natural Sciences and Engineering Research Council of Canada for the financial support.",

year = "2010",

month = jul,

day = "1",

doi = "10.1016/j.tsf.2010.04.002",

language = "English (US)",

volume = "518",

pages = "5345--5348",

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TY - JOUR

T1 - Photogeneration of charges in microcrystalline chlorophyll a

AU - Kassi, Hassan

AU - Barazzouk, Saïd

AU - Brullemans, Marc

AU - Leblanc, Roger M.

AU - Hotchandani, Surat

N1 - Funding Information: We would like to thank Natural Sciences and Engineering Research Council of Canada for the financial support.

PY - 2010/7/1

Y1 - 2010/7/1

N2 - The electric-field and temperature dependence of hole photogeneration in chlorophyll a (Chla) have been analyzed in terms of electric-field assisted thermal dissociation of charge pairs based on Onsager theory. An excellent agreement between the experimental and theoretical values of the slope-to-intercept ratio, S/I, for the plot of photogeneration efficiency vs. electric field at low field strengths provides a proof for the applicability of the Onsager approach to the photogeneration of charges in Chla. A value of 19 nm has been obtained for Coulomb capture radius, rc, from S/I. From the temperature dependence of photogeneration, the initial separation, r 0, of photogenerated electron-hole has been evaluated, and has a value of 1.24 nm. This smaller r0 compared to rc leads to a feeble dissociation probability of electron-hole pairs into free carriers, and may, among other factors, explain the low power conversion efficiencies of Chla photovoltaic cells.

AB - The electric-field and temperature dependence of hole photogeneration in chlorophyll a (Chla) have been analyzed in terms of electric-field assisted thermal dissociation of charge pairs based on Onsager theory. An excellent agreement between the experimental and theoretical values of the slope-to-intercept ratio, S/I, for the plot of photogeneration efficiency vs. electric field at low field strengths provides a proof for the applicability of the Onsager approach to the photogeneration of charges in Chla. A value of 19 nm has been obtained for Coulomb capture radius, rc, from S/I. From the temperature dependence of photogeneration, the initial separation, r 0, of photogenerated electron-hole has been evaluated, and has a value of 1.24 nm. This smaller r0 compared to rc leads to a feeble dissociation probability of electron-hole pairs into free carriers, and may, among other factors, explain the low power conversion efficiencies of Chla photovoltaic cells.

KW - Electric field

KW - Microcrystalline chlorophyll a

KW - Onsager approach

KW - Photocarrier generation

KW - Time-of-flight technique

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DO - 10.1016/j.tsf.2010.04.002

M3 - Article

AN - SCOPUS:77955663320

VL - 518

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JO - Thin Solid Films

JF - Thin Solid Films

SN - 0040-6090

IS - 18

ER -

Photogeneration of charges in microcrystalline chlorophyll a

Abstract

Keywords

ASJC Scopus subject areas

UN SDGs

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