A calorimetric study of the phase transitions in poly(3-hexylthiophene)

Zhao, Yue; Yuan, Guanghui; Roché, Philippe; Leclerc, Mario

doi:10.1016/0032-3861(95)95298-f

Cited by 196 publications

(164 citation statements)

References 13 publications

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“…[ 38,45 ] This is very different from that of polycrystalline polymers such as P3HT, poly(9,9-dioctylfl uorene) (PFO), poly(9,9-dioctylfl uorene-alt -benzothiadiazole) (F8BT), and poly(9,9-dioctylfl uorene-alt -bithiophene), which can have rich and complex DSC spectra showing multiple peaks from glass, crystallization, and melting transitions. [ 36,[46][47][48][49][50][51] The thin fi lm optical absorption spectra of PFB and PFMO (Figure 2 resemble the solution spectra using a good solvent in which the chains are in the random-coil conformation. This is exactly as for TFB, being an expected characteristic of an amorphous semiconducting polymer.…”

Section: Resultsmentioning

confidence: 94%

Charge‐Carrier Density Independent Mobility in Amorphous Fluorene‐Triarylamine Copolymers

Campbell

Rawcliffe

Guite

et al. 2016

Adv Funct Materials

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3720 wileyonlinelibrary.com (OPVs), and organic fi eld-effect transistors (OFETs). A crucial parameter in the development of these technologies is the OSC charge-carrier mobility, and how it is related to the different OSC materials, processing, device architectures, and device operating conditions. Many semiconducting polymers and small molecules are amorphous, and such disorder in the physical morphology is expected to refl ect itself in disorder of the energy levels of the hole and electron transport states ( Figure 1 a). Such energetic disorder will directly impact charge transport and mobility. [1][2][3][4][5][6][7][8][9][10][11][12] For such energetically disordered OSCs, one feature predicted by many charge transport models is a charge-carrier density dependent mobility. The original Gaussian disorder model (GDM) developed by Bässler for hopping transport in a Gaussian density of states (DOS) distribution was a single carrier approach, [ 1 ] as were the models based on it which considered both correlated energetic disorder, [ 2 ] with a smoothly varying energy landscape (see Figure 1 a), and the effect of polaronic relaxation. [ 3 ] The percolation model developed by Vissenberg and Matters for transport involving an exponential DOS instead considered multiple carriers, [ 4 ] and this predicted a mobility which has a power-law dependency on the charge-carrier density. The measured transistor mobility falls two to three orders of magnitude below that predicted from the charge-carrier density dependent model, and does not follow the expected power-law relationship. The experimental results for these two amorphous polymers are therefore consistent with a charge-carrier density independent mobility, and this is discussed in terms of polaron-dominated hopping and interchain correlated disorder.

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Section: Resultsmentioning

confidence: 94%

Charge‐Carrier Density Independent Mobility in Amorphous Fluorene‐Triarylamine Copolymers

Campbell

Rawcliffe

Guite

et al. 2016

Adv Funct Materials

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“…[24] This effect has been observed in heated films of P3HT at as low a temperature as 40ºC. [25] Increased crystallinity, therefore, explains the slight decrease in PL efficiency observed above 120ºC, but fails to account for the substantial increase in PL efficiency below 120ºC. Under annealing at lower temperatures, the removal of excess pyridine within the polymer is the likely cause for the increase in P3HT photoluminescence efficiency with increasing treatment temperature (Fig.…”

Section: Excess Pyridinementioning

confidence: 95%

Controlling the Morphology of Nanocrystal–Polymer Composites for Solar Cells

Huynh

Dittmer

Libby

et al. 2003

Adv Funct Materials

480

403

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We have shown recently that the use of high aspect ratio inorganic nanorods in conjunction with conjugated polymers is a route to obtaining efficient solar cells processed from solution. Here, we demonstrate that the use of binary solvent mixtures in which one of the components is a ligand for the nanocrystals is effective in controlling the dispersion of nanocrystals in a polymer.By varying the concentration of the solvent mixture, phase separation between the nanocrystal and polymer could be tuned from a micron scale down to nanometer scale. In addition, we can achieve nanocrystal surfaces that are free of surfactant through the use of weak binding ligands, which can be removed through heating. Combined, the control of film morphology together with surfactant removal result in nanorod-polymer blend photovoltaic cells with high external quantum efficiency of 59% under 0.1 mW/cm 2 illumination at 450 nm.

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“…At this temperature devitrification of the blend allows the polymer and the fullerene molecules to rearrange/diffuse in the bulk and at the interface with the electrodes. Typically the Tg of a polymer/blend is measured by Differential Scanning Calorimetry (DSC) [39] but other techniques like ellipsometry have also been employed [36] , [40]. Obtained Tg value is not always a well-defined parameter and in many systems a clear transition is not observed.…”

Section: Introductionmentioning

confidence: 99%

Predicting thermal stability of organic solar cells through an easy and fast capacitance measurement

Tessarolo

Guerrero

Gedefaw

et al. 2015

Solar Energy Materials and Solar Cells

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Degradation of Organic Photovoltaic (OPV) devices is currently a topic under intense research as it is one of the main limitations towards the commercialization of this technology. Morphological changes at both active layer and interfaces with the outer contacts are believed to determine main key issues to be overcome. In-line techniques are essential to rule out any effect arising during sample fabrication.Unfortunately, the number of physical techniques able to provide morphological information on complete and operational devices is certainly limited. In this work, we study the thermal degradation of bulk heterojunction (BHJ) solar cells composed by different donor polymers with techniques developed to provide in-situ information on operational devices. Capacitance measurement as a function of temperature monitors the electrical integrity of the active layer and provides the threshold temperature (T MAX ) at which the whole device becomes thermally unstable. We found a direct correlation between the threshold temperature T MAX , obtained by capacitance-temperature measurements on complete OPV devices, and the power conversion efficiency decay measured at 85°C. Devices show to be thermal stable when the temperature of the thermal stress is below the T MAX , while above the T MAX evident changes in the active layer or at the active layer/electrode interface are also detected by confocal fluorescence microscopy. The capacitance method gives precious guidelines to predict the thermal stability of BHJ solar cells using accelerated and easy tests.

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A calorimetric study of the phase transitions in poly(3-hexylthiophene)

Cited by 196 publications

References 13 publications

Charge‐Carrier Density Independent Mobility in Amorphous Fluorene‐Triarylamine Copolymers

Charge‐Carrier Density Independent Mobility in Amorphous Fluorene‐Triarylamine Copolymers

Controlling the Morphology of Nanocrystal–Polymer Composites for Solar Cells

Predicting thermal stability of organic solar cells through an easy and fast capacitance measurement

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