Processing Additives for Improved Efficiency from Bulk Heterojunction Solar Cells

Center for Polymers and Organic Solids, University of California at Santa Barbara, Santa Barbara, California 93106, USA.
Journal of the American Chemical Society (Impact Factor: 12.11). 04/2008; 130(11):3619-23. DOI: 10.1021/ja710079w
Source: PubMed


Two criteria for processing additives introduced to control the morphology of bulk heterojunction (BHJ) materials for use in solar cells have been identified: (i) selective (differential) solubility of the fullerene component and (ii) higher boiling point than the host solvent. Using these criteria, we have investigated the class of 1,8-di(R)octanes with various functional groups (R) as processing additives for BHJ solar cells. Control of the BHJ morphology by selective solubility of the fullerene component is demonstrated using these high boiling point processing additives. The best results are obtained with R = Iodine (I). Using 1,8-diiodooctane as the processing additive, the efficiency of the BHJ solar cells was improved from 3.4% (for the reference device) to 5.1%.

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    • "Different fabrication/processing procedures can lead to substantially different film morphologies even when the same active materials are used. These will be detailed in Section 3. Blends of solvents, the use of additives , manual manipulation of the deposition temperature and the creation of a solvent saturated atmosphere are some of the strategies most commonly used in order to obtain a better control of the film drying process and manipulate the resulting bulk-in morphology [11] [12] [13] [14] [15] [16] [17] [18]. In this way, it is possible to achieve ideal spatial distributions of connected electron and hole favorable domains with sizes in the order of the exciton diffusion length that guarantee efficient charge separation and transport. "
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    Organic Electronics 04/2015; 19. DOI:10.1016/j.orgel.2015.01.014 · 3.83 Impact Factor
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    • "One strategy to control the morphology in donor/acceptor mixtures involves adding a solvent additive, generally at 0.1–10% of the solvent volume [16] [25]. Solvent additives studied include 1,8-diiodooctane (DIO), 1-chloronaphtha- lene, 1,8-octanedithiol, and alkylthiophenes. "
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    Organic Electronics 11/2014; 15(11-11):3384-3391. DOI:10.1016/j.orgel.2014.09.021 · 3.83 Impact Factor
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    • "Chemical structures of investigated compounds. additive [3]. An increase of Á (from 2.8% to 5.5%) following the addition of alkanedithiols was reported in [4]. "
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    ABSTRACT: A light-induced electron spin resonance (LESR) X-band study of poly(3-hexylthiophene)/indene-C60 bisadduct P3HT/ICBA flexible solid films containing the additive maleic anhydride (MA) is presented. An increase of P3HT crystalline domain orientation in P3HT:ICBA:MA in comparison with P3HT:ICBA films was confirmed by the angular LESR spectra dependence of P3HT positive polarons. It was assumed that the average increase of power conversion efficiency in P3HT:ICBA:MA solar cells films, relative to P3HT:ICBA, is connected with the more effective crystalline P3HT phase orientation due to the MA sublimation from the composites blends during annealing. The relative average increase of power conversion efficiency of SC films containing MA in comparison to pure P3HT:ICBA blends is estimated to be a factor of (1.15) higher, while the concentrations of functional composites (polymer/fullerene) in blends made with MA decrease by up to 25–30%.
    Synthetic Metals 11/2014; 197:210–216. DOI:10.1016/j.synthmet.2014.09.012 · 2.25 Impact Factor
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