Absorption Studies of Charged Excitations in a-Sexithiophene

Absorption Studies of Charged Excitations in a-Sexithiophene

NREL

Chemistry and Nanoscience

Research output: Contribution to conference › Paper

Abstract

We present photoexcitation studies of vacuum deposited neutral films of .alpha..omega.-substituted sexithiophene (.alpha.-6T) using photoinduced absorption (PA) and PA-detected magnetic resonance spectroscopy (PADMR). We find evidence for photoinduced polarons having spin 1/2, with two absorption bands at 0.80 and 1.54 eV, respectively, and with negative PADMR signal at g .apprxeq.2. Similarabsorption bands are observed in lightly p-doped sexithiophene and are interpreted as due to 6T.bul.+ radical cations. In addition, a PA band is found at 1.1 eV, which is shorter lived and decreases faster with increasing temperature than the polaron bands. As similar dication bands (6T.sup.2+) have been found in heavily-doped .alpha.-6T, we identify this band as due to spinless bipolarons.Evidence of charge conjugation symmetry breaking in .alpha.-6T is presented. Finally, we have identified triplet excitons with triplet-triplet transition energy at about 1.45 eV.

Original language	American English
Pages	Vol. 2: 1338-1342
Number of pages	5
State	Published - 1996
Event	ANTEC '96: Annual Technical Conference of the Society of Plastics Engineers 1996 - Duration: 1 Jan 1996 → 1 Jan 1996

Conference

Conference	ANTEC '96: Annual Technical Conference of the Society of Plastics Engineers 1996
Period	1/01/96 → 1/01/96

NLR Publication Number

NREL/CP-590-25344

Cite this

@conference{96268e3b236b47f19c3716ec0d02acd2,

title = "Absorption Studies of Charged Excitations in a-Sexithiophene",

abstract = "We present photoexcitation studies of vacuum deposited neutral films of .alpha..omega.-substituted sexithiophene (.alpha.-6T) using photoinduced absorption (PA) and PA-detected magnetic resonance spectroscopy (PADMR). We find evidence for photoinduced polarons having spin 1/2, with two absorption bands at 0.80 and 1.54 eV, respectively, and with negative PADMR signal at g .apprxeq.2. Similarabsorption bands are observed in lightly p-doped sexithiophene and are interpreted as due to 6T.bul.+ radical cations. In addition, a PA band is found at 1.1 eV, which is shorter lived and decreases faster with increasing temperature than the polaron bands. As similar dication bands (6T.sup.2+) have been found in heavily-doped .alpha.-6T, we identify this band as due to spinless bipolarons.Evidence of charge conjugation symmetry breaking in .alpha.-6T is presented. Finally, we have identified triplet excitons with triplet-triplet transition energy at about 1.45 eV.",

author = "NREL",

year = "1996",

language = "American English",

pages = "Vol. 2: 1338--1342",

note = "ANTEC \'96: Annual Technical Conference of the Society of Plastics Engineers 1996 ; Conference date: 01-01-1996 Through 01-01-1996",

}

TY - CONF

T1 - Absorption Studies of Charged Excitations in a-Sexithiophene

AU - NREL, null

PY - 1996

Y1 - 1996

N2 - We present photoexcitation studies of vacuum deposited neutral films of .alpha..omega.-substituted sexithiophene (.alpha.-6T) using photoinduced absorption (PA) and PA-detected magnetic resonance spectroscopy (PADMR). We find evidence for photoinduced polarons having spin 1/2, with two absorption bands at 0.80 and 1.54 eV, respectively, and with negative PADMR signal at g .apprxeq.2. Similarabsorption bands are observed in lightly p-doped sexithiophene and are interpreted as due to 6T.bul.+ radical cations. In addition, a PA band is found at 1.1 eV, which is shorter lived and decreases faster with increasing temperature than the polaron bands. As similar dication bands (6T.sup.2+) have been found in heavily-doped .alpha.-6T, we identify this band as due to spinless bipolarons.Evidence of charge conjugation symmetry breaking in .alpha.-6T is presented. Finally, we have identified triplet excitons with triplet-triplet transition energy at about 1.45 eV.

AB - We present photoexcitation studies of vacuum deposited neutral films of .alpha..omega.-substituted sexithiophene (.alpha.-6T) using photoinduced absorption (PA) and PA-detected magnetic resonance spectroscopy (PADMR). We find evidence for photoinduced polarons having spin 1/2, with two absorption bands at 0.80 and 1.54 eV, respectively, and with negative PADMR signal at g .apprxeq.2. Similarabsorption bands are observed in lightly p-doped sexithiophene and are interpreted as due to 6T.bul.+ radical cations. In addition, a PA band is found at 1.1 eV, which is shorter lived and decreases faster with increasing temperature than the polaron bands. As similar dication bands (6T.sup.2+) have been found in heavily-doped .alpha.-6T, we identify this band as due to spinless bipolarons.Evidence of charge conjugation symmetry breaking in .alpha.-6T is presented. Finally, we have identified triplet excitons with triplet-triplet transition energy at about 1.45 eV.

M3 - Paper

SP - Vol. 2: 1338-1342

T2 - ANTEC '96: Annual Technical Conference of the Society of Plastics Engineers 1996

Y2 - 1 January 1996 through 1 January 1996

ER -

Absorption Studies of Charged Excitations in a-Sexithiophene

Abstract

Conference

NLR Publication Number

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