Acceptor dependent polaron recombination dynamics in poly 3-hexyl thiophene: Fullerene composite films

Busby, Erik; Rochester, Christopher W.; Moulé, Adam J.; Larsen, Delmar S.

doi:10.1016/j.cplett.2011.07.066

Cited by 8 publications

(13 citation statements)

References 52 publications

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“…These predicted recombination constants are presented in Figure S8 in the supporting information and they confirm the observation from literature that non‐geminate recombination in P3HT based devices is substantially slower than in PCDTBT or SiPCPDTBT based devices. In addition, we reproduce the observation in literature that recombination at room temperature is similarly fast in P3HT blended with different fullerenes as shown by Guerrero et al65 and Busby et al66 and that SiPCPDTBT:PCBM and SiPCPDTBT: bis ‐PCBM have similar lifetimes as shown by Azimi et al35 The only cases, where the fullerene has a strong effect on the predicted recombination constants are the cases of SiPCPDTBT:ICBA and PCDTBT:ICBA, which seem to have much faster recombination than the other blends. Note that we cannot exclude effects like field dependent charge generation in these cases, which would have a similar effect than non‐geminate recombination: Field dependent charge generation would decrease the fill factor and short circuit current of the solar cells without affecting the current/voltage curves of the single carrier devices.…”

Section: Resultssupporting

confidence: 90%

Understanding the Reduced Efficiencies of Organic Solar Cells Employing Fullerene Multiadducts as Acceptors

Faist

Shoaee

Tuladhar

et al. 2013

Advanced Energy Materials

132

140

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The use of fullerenes with two or more adducts as acceptors has been recently shown to enhance the performance of bulk‐heterojunction solar cells using poly(3‐hexylthiophene) (P3HT) as the donor. The enhancement is caused by a substantial increase in the open‐circuit voltage due to a rise in the fullerene lowest unoccupied molecular orbital (LUMO) level when going from monoadducts to multiadducts. While the increase in the open‐circuit voltage is obtained with many different polymers, most polymers other than P3HT show a substantially reduced photocurrent when blended with fullerene multiadducts like bis‐PCBM (bis adduct of Phenyl‐C61‐butyric acid methyl ester) or the indene C60 bis‐adduct ICBA. Here we investigate the reasons for this decrease in photocurrent. We find that it can be attributed partly to a loss in charge generation efficiency that may be related to the LUMO‐LUMO and HOMO‐HOMO (highest occupied molecular orbital) offsets at the donor‐acceptor heterojunction, and partly to reduced charge carrier collection efficiencies. We show that the P3HT exhibits efficient collection due to high hole and electron mobilities with mono‐ and multiadduct fullerenes. In contrast the less crystalline polymer Poly[[9‐(1‐octylnonyl)‐9H‐carbazole‐2,7‐diyl]‐2,5‐thiophenediyl‐2,1,3‐benzothiadiazole‐4,7‐diyl‐2,5‐thiophenediyl (PCDTBT) shows inefficient charge carrier collection, assigned to low hole mobility in the polymer and low electron mobility when blended with multiadduct fullerenes.

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Section: Resultssupporting

confidence: 90%

Understanding the Reduced Efficiencies of Organic Solar Cells Employing Fullerene Multiadducts as Acceptors

Faist

Shoaee

Tuladhar

et al. 2013

Advanced Energy Materials

132

140

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“…The mutual miscibility of Lu‐PCBEH/P3HT is expected to be higher than that of Lu‐PCBM/P3HT due to the ethyl‐hexyl side‐chain. We expect that the miscibility of Lu‐PCBEH is similar to C 60 ‐PCBM because transient absorption measurements of BHJs show similar separated charge recombination rates over a wide temperature and composition range 39. Fabricated devices also show similar short‐circuit current and filling factors21, 22 and our tomography measurements show approximately 30 vol% Lu‐PCBEH is present when intermixed with amorphous P3HT.…”

Section: Introductionmentioning

confidence: 60%

Three‐Dimensional Concentration Mapping of Organic Blends

Roehling

Batenburg

Swain

et al. 2012

Adv Funct Materials

Self Cite

100

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The three‐dimensional morphology of mixed organic layers are quantitatively measured using high‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) with electron tomography for the first time. The mixed organic layers used for organic photovoltaic applications have not been previously imaged using STEM tomography as there is insufficient contrast between donor and acceptor components. Contrast is generated by substituting fullerenes with endohedral fullerenes that contain a Lu3N cluster within the fullerene cage. The high contrast and signal‐to‐noise ratio, in combination with use of the discrete algebraic reconstruction technique (DART), allows generation of the most detailed and accurate three‐dimensional map of BHJ morphology to date. From the STEM‐tomography reconstructions it is determined that three distinct material phases are present within the BHJs. By observing changes to morphology and mixing ratio during thermal and solvent annealing, the effects of mutual solubility and fullerene crystallization on morphology and long term stability are determined. This material/technique combination shows itself as a powerful tool for examining morphology in detail and allows for observation of nanoscopic changes in local concentration.

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“…The PL decay times found for the P3HT:TP film obtained in trichlorobenzene (s 1 = 1950 ps and s 2 = 1840 ps) were the longest, and can be associated with P3HT aggregates. 48,49 In aggregated P3HT, charge separation followed by carrier diffusion and recombination via tunneling is associated with long-time photoluminescence decay. 50,51 The output and transfer curves for the transistors formed using P3HT:TP blend films prepared with chloroform, toluene, and trichlorobenzene are shown in Figs.…”

Section: Resultsmentioning

confidence: 99%

Solvent Effect on Morphology and Optical Properties of Poly(3-hexylthiophene):TIPS-Pentacene Blends

Ozório

Camacho

Cordeiro

et al. 2017

Journal of Elec Materi

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Optical, electrical, and morphological properties of poly(3-hexylthiophene):6,13-bis(triisopropylsilylethynyl) (TIPS)-pentacene (P3HT:TP) blend films, in the proportion of 1:1 (w/w), have been investigated using chloroform, toluene, or trichlorobenzene as solvent. The main morphological feature was formation of aggregates that tended to segregate vertically, exhibiting characteristics that were strongly influenced by the type of solvent applied. The phase segregation of TP observed for the P3HT:TP blend film obtained using chloroform, the most volatile of the investigated solvents, can be explained based on the Marangoni effect and the Flory-Huggins model. The TP molecules induce better organization of P3HT, as evidenced by the ultravioletvisible (UV-Vis) absorption spectra. Photoluminescence (PL) measurements revealed quenching and an increase in the lifetime of the carriers. The PL measurements also showed that the exciton dissociation was dependent on the characteristics of the surface on which the film was deposited. P3HT:TP blend film prepared using trichlorobenzene showed the best morphology with moderate phase segregation and better P3HT ordering. The output current from organic field-effect transistors (OFETs) with blend film prepared using trichlorobenzene was three times (39) larger than when using the other solvents, with carrier mobility of 5.0 9 10 À3 cm 2 V À1 s À1 .

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Acceptor dependent polaron recombination dynamics in poly 3-hexyl thiophene: Fullerene composite films

Cited by 8 publications

References 52 publications

Understanding the Reduced Efficiencies of Organic Solar Cells Employing Fullerene Multiadducts as Acceptors

Understanding the Reduced Efficiencies of Organic Solar Cells Employing Fullerene Multiadducts as Acceptors

Three‐Dimensional Concentration Mapping of Organic Blends

Solvent Effect on Morphology and Optical Properties of Poly(3-hexylthiophene):TIPS-Pentacene Blends

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