Charge transport analysis of poly(3-hexylthiophene) by electroreflectance spectroscopy

Pittner, Steve; Lehmann, Daniel; Zahn, Dietrich R. T.; Wagner, Veit

doi:10.1103/physrevb.87.115211

Cited by 9 publications

(4 citation statements)

References 22 publications

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“…Meanwhile, a lot of work aiming at a better understanding of the elementary processes relevant to the functioning of organic semiconductor devices has focused on investigating the exciton dynamics at the interfaces between the domains of the active polymers. − However, elementary exciton processes at the interface between the metal contact and the polymer layer have not been in the focus of researchers up to now. Many works have shown that the investigation of the energy-level alignment at the metal–organic interfaces using different techniques like ultraviolet photoemission spectroscopy (UPS) or X-ray photoemission spectroscopy (XPS) and so forth − yields insights into the magnitudes of energy barriers, which arise from the mismatch between the Fermi levels of the polaron states of the organic semiconductor materials and the metal electrode and which strongly influence charge-transfer processes at the metal contact. The presumably best studied model system for electronic devices based on conjugated polymers is the contact between gold and poly(3-hexylthiophene) (Au–P3HT).…”

Section: Introductionmentioning

confidence: 99%

“…To study the charge transport, which occurs in the accumulation layer buried at the interface between organic semiconductor and insulator, Pittner et al applied electroreflectance (ER) spectroscopy and used it as spatially resolved method for charge modulation analysis. In their work, these authors gained information about the energetic disorder inside the P3HT-SiO 2 accumulation layer, which has an effect on the local charge transport.…”

Section: Introductionmentioning

confidence: 99%

“…P3HT is a very promising material for applications of organic electronics, and gold is used because of its very good ohmic contact with P3HT, since the highest occupied molecular orbital (HOMO) level of P3HT and the work function of gold are very close to each other. 22,24−26 To study the charge transport, which occurs in the accumulation layer buried at the interface between organic semiconductor and insulator, Pittner et al 27 applied electroreflectance (ER) spectroscopy and used it as spatially resolved method for charge modulation analysis. In their work, these authors gained information about the energetic disorder inside the P3HT-SiO 2 accumulation layer, which has an effect on the local charge transport.…”

Section: ■ Introductionmentioning

confidence: 99%

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Femtosecond Time-Resolved Transient Absorption Spectroscopy with Sub-Diffraction-Limited Spatial Resolution Reveals Accelerated Exciton Loss at Gold-Poly(3-Hexylthiophene) Interface

et al. 2018

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Molecules are known to change properties when in contact with metal surfaces. Therefore, dynamics of photoinduced molecular excitons in a semiconductor also are expected to be influenced by a metal contact. This effect, which is of considerable interest also for applications, is limited to interface excitons generated within just a few nanometer proximity to a metal layer. Up to now, however, a highly localized access to such excitonic events has not been presented, and diffraction-limited microspectroscopy did not yield any pattern in exciton dynamics other than that of bulk excitons, irrespective of an existing metal interface. In our work, we have combined femtosecond time-resolved spectroscopy with scanning near-field optical microscopy (SNOM) to study the interfacial dynamics of a gold-poly(3-hexylthiophene) system (Au–P3HT) making use of tip-enhancement of the light fields of the ultrashort laser pulses by a gold rim surrounding the SNOM fiber tip, which collects the signal light. Next to annihilation of free excitons in P3HT, which is an efficient loss mechanism at the laser powers employed, a direct exciton decay highly confined within the near-field range right at the Au–P3HT interface has been observed. We show that the occurrence of the gold-coated SNOM-tip-induced near-field enhancement of the optical fields permits selective access to the highly confined interfacial exciton decay. The experiments reveal that the early ultrafast loss of charge pairs in P3HT becomes significantly faster at the Au–P3HT interface because of an additional pathway.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Femtosecond Time-Resolved Transient Absorption Spectroscopy with Sub-Diffraction-Limited Spatial Resolution Reveals Accelerated Exciton Loss at Gold-Poly(3-Hexylthiophene) Interface

et al. 2018

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“…Furthermore the impact of time dependent polymerizing potential of ePT during the growth process is analyzed. Polythiophenes in the form of poly-3-hexylthiophene (P3HT) have been studied extensively not only for photovoltaic properties but also for transport properties [15,16]. It has been previously shown that the use of P3HT between the P3HT- [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) bulk heterojunction active layer and the anode serves as an effective electron blocking layer [17].…”

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confidence: 99%

Cyclic potential growth mechanism for electropolymerized polythiophenes as anode buffer layers in P3HT–PCBM solar cells

Bom

Ortel

Wagner

2014

Physica Status Solidi (a)

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A new method for electropolymerization of polythiophenes as anode buffer layer in combination with a PEDOT:PSS buffer in P3HT–PCBM solar cells is introduced. This approach uses a stack of PEDOT:PSS and electropolymerized polythiophene (ePT) as an anode buffer layer. A significant improvement in the short circuit current is seen in solar cells with additional thin buffer layers of ePT grown on top of PEDOT:PSS. The cells with ePT buffer layer grown with constant potential mode compared to solar cells without additional ePT buffer layer have an 18.7% increase in power conversion efficiency. However, the cells with ePT grown with cyclic potential mode result in an additional enhancement in short circuit current with a further increase of 11.7% in power conversion efficiency. This improvement is attributed to better quality of the buffer layer obtained by cyclic potential electropolymerization technique with respect to film quality and area coverage.

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Controlled electrodeposition of ZnO nanostructures for enhanced light scattering properties

et al. 2014

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Charge transport analysis of poly(3-hexylthiophene) by electroreflectance spectroscopy

Cited by 9 publications

References 22 publications

Femtosecond Time-Resolved Transient Absorption Spectroscopy with Sub-Diffraction-Limited Spatial Resolution Reveals Accelerated Exciton Loss at Gold-Poly(3-Hexylthiophene) Interface

Femtosecond Time-Resolved Transient Absorption Spectroscopy with Sub-Diffraction-Limited Spatial Resolution Reveals Accelerated Exciton Loss at Gold-Poly(3-Hexylthiophene) Interface

Cyclic potential growth mechanism for electropolymerized polythiophenes as anode buffer layers in P3HT–PCBM solar cells

Controlled electrodeposition of ZnO nanostructures for enhanced light scattering properties

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