Effect of annealing of poly(3-hexylthiophene)/fullerene bulk heterojunction composites on structural and optical properties

Zhokhavets, Uladzimir; Erb, Tobias; Hoppe, Harald; Gobsch, G.; Sariciftci, Niyazi Serdar

doi:10.1016/j.tsf.2005.09.093

Cited by 163 publications

(146 citation statements)

References 19 publications

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“…It has been reported that postfabrication annealing of films of OPVC material pairs 5,53 and pure C60 layers 24 was able to impact the structural, surface and electrical properties, which can lead to a device efficiency improvement. Therefore, we investigated the impact of annealing on the PEN+ C60 film deposited on the PEN underlayer; the XRD results are shown in Fig.…”

Section: Structural Investigationsmentioning

confidence: 99%

Structural and electronic properties of pentacene-fullerene heterojunctions

Salzmann

Duhm

Opitz

et al. 2008

Journal of Applied Physics

101

104

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In this study the performance differences of layered and bulk-heterojunction based organic solar cells composed of the prototypical p-and n-type organic semiconductors pentacene ͑PEN͒ and fullerene ͑C60͒ are correlated with the physical properties of the heterostructures. The electronic structure of layered and codeposited thin PEN and C60 films on the conducting polymer substrate poly͑ethylenedioxythiophene͒:poly͑styrenesulfonate͒ ͑PEDOT:PSS͒ was investigated with ultraviolet photoelectron spectroscopy. Layered structures of C60 on PEN precovered PEDOT:PSS exhibited an offset of the highest occupied molecular orbital ͑HOMO͒ levels of 1.45 eV. In contrast, codeposited films of PEN and C60 showed a reduced HOMO-level offset of 0.85 eV, which increased to 1.45 eV by precoverage of the substrate with a thin PEN layer. In this case, the PEN-HOMO level was Fermi-level pinned at 0.35 eV binding energy and charge transfer between PEN and PEDOT:PSS decreased the vacuum level by 0.75 eV. In addition, the morphology and crystal structure of the respective systems have been investigated by atomic force microscopy ͑AFM͒, x-ray diffraction ͑XRD͒ and Fourier-transform infrared spectroscopy, which indicated pronounced phase separation of PEN and C60 in the codeposited films. XRD revealed crystalline growth of PEN in all investigated cases forming crystallites that exceeded the nominal film thickness by an order of magnitude, whereas C60 was crystalline only if grown on the PEN precovered substrates. AFM investigations allowed to correlate morphology and structure revealing micro-and nanophase separation between PEN and C60.

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Section: Structural Investigationsmentioning

confidence: 99%

Structural and electronic properties of pentacene-fullerene heterojunctions

Salzmann

Duhm

Opitz

et al. 2008

Journal of Applied Physics

101

104

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“…1,2 Thermal or solvent annealing is typically used to alter the morphology of the device active layer on the nanoscale. [3][4][5][6] However, the blend film structure is a complex interplay of crystalline and amorphous mixed and demixed regions.…”

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confidence: 99%

Molecular versus crystallite PCBM diffusion in P3HT:PCBM blends

Berriman¹,

Holdsworth²,

Zhou³

et al. 2015

AIP Advances

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The diffusion of PCBM in P3HT:PCBM blend films has been investigated using multi-wavelength scanning absorption microscopy (MWSAM). By studying the depletion of PCBM in the vicinity of the phase segregated PCBM-rich regions that form upon thermal annealing, we are able to measure the diffusion constant and activation energy for PCBM diffusion in P3HT:PCBM blend films. The measured kinetic parameters are consistent with the diffusion of nanoscale PCBM crystallites rather than molecular PCBM. We show that the presence of two distinct diffusion processes in these blend materials provides an explanation for the large differences that have been reported for PCBM diffusion in P3HT:PCBM blends. This insight allows us to develop a unified model for PCBM mass transport in these materials.

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“…[1][2][3][4] Like other organic electronic devices, [5][6][7] charge injection at the organicinorganic interface is a key issue for OPVs. 8,9 Surface treatments of electrode including oxidation, the addition of a selfassembled layer, [10][11][12][13][14] or poly͑3,4-ethylene dioxythiophene͒: poly͑styrene-sulfonate͒ ͑PEDOT:PSS͒ layer insertion 15 can lower or raise the work functions of cathodes and anodes, or enhance the cohesion, and thus lower the interfacial series resistance.…”

mentioning

confidence: 99%