The Effect of a Mild Thermal Treatment on the Performance of Poly(3-alkylthiophene)/Fullerene Solar Cells

Camaioni, Nadia; Ridolfi, Giovanni; Casalbore-Miceli, G.; Possamai, Giorgia; Maggini, Michele

doi:10.1002/1521-4095(20021203)14:23<1735::aid-adma1735>3.0.co;2-o

Cited by 174 publications

(119 citation statements)

References 8 publications

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“…Similar results have been reported by other authors. [10,30] Furthermore, the mobility measurements presented in Figure 3, correlated with the morphology investigations [15,[27][28][29] indicate that there is a change in the physical conformation of the P3HT chains. As a result, the packing …”

Section: Optical Absorption Spectrasupporting

confidence: 57%

Charge Transport and Photocurrent Generation in Poly(3-hexylthiophene): Methanofullerene Bulk-Heterojunction Solar Cells

et al. 2006

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The effect of controlled thermal annealing on charge transport and photogeneration in bulk‐heterojunction solar cells made from blend films of regioregular poly(3‐hexylthiophene) (P3HT) and methanofullerene (PCBM) has been studied. With respect to the charge transport, it is demonstrated that the electron mobility dominates the transport of the cell, varying from 10–8 m2 V–1 s–1 in as‐cast devices to ≈3 × 10–7 m2 V–1 s–1 after thermal annealing. The hole mobility in the P3HT phase of the blend is dramatically affected by thermal annealing. It increases by more than three orders of magnitude, to reach a value of up to ≈ 2 × 10–8 m2 V–1 s–1 after the annealing process, as a result of an improved crystallinity of the film. Moreover, upon annealing the absorption spectrum of P3HT:PCBM blends undergo a strong red‐shift, improving the spectral overlap with solar emission, which results in an increase of more than 60 % in the rate of charge‐carrier generation. Subsequently, the experimental electron and hole mobilities are used to study the photocurrent generation in P3HT:PCBM devices as a function of annealing temperature. The results indicate that the most important factor leading to a strong enhancement of the efficiency, compared with non‐annealed devices, is the increase of the hole mobility in the P3HT phase of the blend. Furthermore, numerical simulations indicate that under short‐circuit conditions the dissociation efficiency of bound electron–hole pairs at the donor/acceptor interface is close to 90 %, which explains the large quantum efficiencies measured in P3HT:PCBM blends.

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Section: Optical Absorption Spectrasupporting

confidence: 57%

Charge Transport and Photocurrent Generation in Poly(3-hexylthiophene): Methanofullerene Bulk-Heterojunction Solar Cells

et al. 2006

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“…[6,21,22] It has been widely reported that the P3HT absorption red-shifts and a series of vibronic peaks become visible at k ∼ 600 nm, 550 nm, and 510 nm. [6,11] This red-shift has been assigned to increased planarization and stabilization of the P3HT chains that accompanies self-stacking of the polymer.…”

Section: By Adam J Moulé and Klaus Meerholz*mentioning

confidence: 99%

Controlling Morphology in Polymer–Fullerene Mixtures

2007

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In the past several years, polymer-fullerene mixtures have been intensely studied for use in organic solar cells because they can be deposited from solution, are compatible with lowcost roll-to-roll fabrication technology, and have shown high power conversion efficiency (g), up to 4-5%. [1][2][3] The best devices consist of a single bulk-heterojunction active layer, in which the polymer (donor) and fullerene (acceptor) are deposited from a common solvent. As the solvent dries the donor and acceptor components separate into domains. The final efficiency of the solar cell has been shown to be extremely sensitive to the size, composition, and crystallinity of the formed domains. [4,5] Improvement of the morphology in devices fabricated with a mixture of [6,6]-phenyl C 61 -butyric acid methyl ester (PCBM) and regioregular poly(3-hexylthiophene) (P3HT) has been achieved by using heat-treatment techniques [2,6] and long-time solvent curing, [1] with resulting record efficiencies. More recently, a method for increasing the crystallinity of the P3HT component has been introduced which involves filtering preformed nanofibers of P3HT out of solution and mixing the prepared nanofiber dispersion with PCBM to increase the efficiency of as-cast devices. [7] Interestingly, the best device performance was achieved by mixing lower-molecular-weight (M W ) amorphous P3HT back into the solution to reduce the crystalline content of the active layer and, thereby, to increase connection between crystalline domains. Studies of the M W impact on P3HT/PCBM solar cells have indicated that a large polydispersity and number-average molecular weight (M n ) over 19000 g mol -1 leads to improved efficiency. [8,9] Morphology studies of organic field-effect transistor (OFET) devices indicate that the increased M W leads to better network formation between crystalline domains. [10,11]

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“…Results from these studies point out that the optimum blend ratio is between 1:0.9 and 1:1, but fail short of specifying the exact optimal ratio (Woehrle and Meissner, 1991). Some other studies however have made mention of 1:1 as the optimal ratio while others have mentioned 1:0.80 or 1:0.43 (Camaioni et al, 2002;Dennler et al, 2009;Chen et al, 2009). This study specifically focuses on the blend ratio range 1: 0.80 -1:1.…”

Section: Introductionmentioning

confidence: 97%

Characterization and optimization of poly (3-hexylthiophene-2, 5- diyl) (P3HT) and [6, 6] phenyl-C61-butyric acid methyl ester (PCBM) blends for optical absorption

Kalonga¹,

Chinyama²,

Munyati³

et al. 2013

J. Chem. Eng. Mater. Sci.

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Thin films were developed, characterized, and optimized for optical absorbance from blends of organic polymer poly (3-hexylthiophene-2, 5-diyl) (P3HT) and the fullerene derivative [6, 6] phenyl-C 61 -butyric acid methyl ester (PCBM). The materials of both pristine and blends were analyzed using X-ray diffraction spectroscopy and high resolution transmission electron microscopy for structural properties, and fourier transform infra-red and UV-VIS spectroscopy for optical properties. The study evaluated the effects of altering the blend ratio and annealing temperature on absorption. The ratios were made by varying the weight of PCBM whilst keeping that of P3HT constant. Eleven different ratios were made with each exhibiting its own optimal annealing temperature and absorption. The optimum ratio was determined and found to be at 1:1 with an annealing temperature of 100ºC for 30 min duration.

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The Effect of a Mild Thermal Treatment on the Performance of Poly(3-alkylthiophene)/Fullerene Solar Cells

Cited by 174 publications

References 8 publications

Charge Transport and Photocurrent Generation in Poly(3-hexylthiophene): Methanofullerene Bulk-Heterojunction Solar Cells

Charge Transport and Photocurrent Generation in Poly(3-hexylthiophene): Methanofullerene Bulk-Heterojunction Solar Cells

Controlling Morphology in Polymer–Fullerene Mixtures

Characterization and optimization of poly (3-hexylthiophene-2, 5- diyl) (P3HT) and [6, 6] phenyl-C61-butyric acid methyl ester (PCBM) blends for optical absorption

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