Understanding the effect of solvent vapor annealing on solution-processed A–D–A oligothiophene bulk-heterojunction solar cells: the role of alkyl side chains

Wessendorf, Cordula D.; Pérez-Rodríguez, Ana; Hanisch, Jonas; Arndt, Andreas P.; Ata, Ibrahim; Schulz, Gisela L.; Quintilla, Aina; Bäuerle, Peter; Lemmer, Uli; Wochner, P.; Ahlswede, Erik; Barrena, Esther

doi:10.1039/c5ta07713c

Cited by 48 publications

(35 citation statements)

References 49 publications

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“…Beyond this, however, optimization of the SVA method has primarily been limited to screening exposure time of one given solvent. Typically, the choice of SVA solvent is chosen to be the same one from which the BHJ was cast . Yet in some cases the choice is peculiar .…”

Section: Introductionmentioning

confidence: 99%

Toward a Universally Compatible Non‐Fullerene Acceptor: Multi‐Gram Synthesis, Solvent Vapor Annealing Optimization, and BDT‐Based Polymer Screening

et al. 2018

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To highlight the benefits of the organic dye PDI-DPP-PDI for use in fullerenefree organic solar cells, herein is demonstrated how this material can meet scalability demands through a multigram scale direct heteroarylation coupling reaction, and performance demands through a post-deposition solvent vapor annealing treatment. A solvent vapor annealing method has been utilized to screen a comprehensive selection of ethereal, aromatic, and chlorinated solvents. Upon transitioning to these eight alternative solvents, significant performance increase over the chloroform standard is noted for all solvents, with tetrahydrofuran and o-dichlorobenzene leading to the highest performance devices post-treatment. This trend, including an open-circuit voltage greater than 1 V proved to be consistent with four different BDT-based donor polymers, PTB7-Th, PBDB-T, J61, and TTFQx-T1. The highest performing devices are achieved with PTB7-Th and TTFQx-T1, with PCEs reaching 6.2 and 5.7%, respectively, when tetrahydrofuran solvent vapor annealing is combined with interfacial modification of the ZnO electron-transport layer.

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Section: Introductionmentioning

confidence: 99%

Toward a Universally Compatible Non‐Fullerene Acceptor: Multi‐Gram Synthesis, Solvent Vapor Annealing Optimization, and BDT‐Based Polymer Screening

et al. 2018

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“…[30,33,34] Adv. [36,37] In Figures S7 and S8 (Supporting Information), atomic force microscopy (AFM) height and phase images confirm the dominantly homogenous, finescale morphologies achieved with SM1 and SM2; root-meansquare (RMS) roughness: 0.5-2.2 nm (cf. 2017, 7, The relative coarsening of the donor and acceptor-rich phases (clear and darker domains, respectively) apparent on comparing "as-cast" (Figure S10a,c, Supporting Information) and optimized BHJ thin films ( Figure S10b,d, Supporting Information) (cf.…”

Section: Device Testing and Characterizationsmentioning

confidence: 85%

Benzo[1,2‐b:4,5‐b′]Dithiophene–6,7‐Difluoroquinoxaline Small Molecule Donors with >8% BHJ Solar Cell Efficiency

Liang

Wang

Wolf

et al. 2017

Advanced Energy Materials

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In particular, in recent work, we showed that the development of BHJ morphologies between donor and acceptor components, [20] material processing, and optimization of thin-film morphologies via postprocessing treatments [21] is not independent of the substitution pattern and functional groups appended to SM donors. As a result, the rational design of SM donors with gradually improved BHJ solar cell efficiencies must concurrently address: (i) bandgap tuning and optimization of spectral absorption (inherent to the SM main chain) and (ii) pendant-group substitution promoting structural order and mediating morphological effects.In this contribution, we report on the rational pendant-group substitution and concurrent bandgap reduction in benzo[1,2-b:4,5-b′]dithiophene-6,7-difluoroquinoxaline SM donors, raising BHJ solar cell efficiencies from ≈6 to >8% with PC 71 BM, and we provide a detailed understanding of the role of the selective substitutions on material and BHJ device performance improvements. Taking advantage of the synthetic modularity of electrondeficient quinoxaline motifs, we show that the introduction of acrylate functions on the pyrazine ring is an effective approach to significantly increasing the electron affinity of the acceptor unit, in turn narrowing the optical gap of the SM donor. Importantly, our device examinations show that this discrete synthetic modification does not alter the propensity of benzo[1,2-b:4,5-b′]dithiophene-6,7-difluoroquinoxaline SM donors to order and form favorable thin-film BHJ morphologies with PCBM; carrier extraction in optimized BHJ active layers proceeds with notably suppressed geminate and bimolecular recombination, while the high open-circuit voltage (V OC ) of the BHJ solar cells is maintained to ≈1 V.In the design of symmetrical SM donors alternating donor and acceptor motifs (DADAD) setting their optical gap, two avenues have prevailed thus far: (i) swapping the donor [acceptor] units for more electron-rich [-deficient] motifs-albeit with distinctly different molecular structure [14,22] -and (ii) increasing [reducing] their conjugation length by replicating [removing] DA motifs [14] or, more commonly, by varying the number of rings involved in the main chain. [1,17] In either cases, the synthetic modifications generally impact SM self-assembly in thin films, solution-processing and device optimization procedures, [18,23] Solution-processable small molecule (SM) donors are promising alternatives to their polymer counterparts in bulk-heterojunction (BHJ) solar cells. While SM donors with favorable spectral absorption, self-assembly patterns, optimum thin-film morphologies, and high carrier mobilities in optimized donor-acceptor blends are required to further BHJ device efficiencies, material structure governs each one of those attributes. As a result, the rational design of SM donors with gradually improved BHJ solar cell efficiencies must concurrently address: (i) bandgap tuning and optimization of spectral absorption (inherent to the SM main chain) and (ii) pendant...

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“…For each type, there are several techniques applied. Physical deposition techniques for thin organic films include physical vapor deposition (PVD) [38][39][40][41][42], organic vapor phase deposition (OVPD) [43][44][45], organic molecular beam deposition (OMBD) [46][47][48][49][50][51], solvent vapor annealing (SVA) [52][53][54][55][56], self-assembled monolayers (SAMs) [57,58], inkjet printing [59,60], pulsed laser deposition (PDL) [61][62][63][64], and laser evaporation [65][66][67] techniques. The chemical methods include solution techniques and gas-phase deposition methods.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Nonlinear Optical Studies on Organic Compounds in Laser-Deposited Films

Marinescu¹

2019

Applied Surface Science

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Organic semiconductors as active materials in thin-film electronic devices such as alkynes, heterocycles, dyes, ferrocenes, spiranes, or porphyrins, with special geometries and certain electronic molecular parameters, which possess nonlinear optical (NLO) properties and offer several major advantages over their inorganic counterparts, are presented in this chapter. There are a number of simple and versatile techniques that can be employed for the deposition of these important classes of materials. The matrix-assisted pulsed laser evaporation (MAPLE) technique provides advantages with regard to making organic films of different morphologies on different types of substrates. New insights into the crystallization growth mechanisms in MAPLE-deposited conjugated polymer films, which realize the connection between the structure and the carrier transport properties, are discussed herein. Second harmonic generation (SHG) capabilities of the thin films were also investigated.

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Understanding the effect of solvent vapor annealing on solution-processed A–D–A oligothiophene bulk-heterojunction solar cells: the role of alkyl side chains

Abstract: Solvent vapor annealing (SVA) can strongly influence the morphology of oligomer:fullerene based organic solar cells.

Cited by 48 publications

References 49 publications

Toward a Universally Compatible Non‐Fullerene Acceptor: Multi‐Gram Synthesis, Solvent Vapor Annealing Optimization, and BDT‐Based Polymer Screening

Toward a Universally Compatible Non‐Fullerene Acceptor: Multi‐Gram Synthesis, Solvent Vapor Annealing Optimization, and BDT‐Based Polymer Screening

Benzo[1,2‐b:4,5‐b′]Dithiophene–6,7‐Difluoroquinoxaline Small Molecule Donors with >8% BHJ Solar Cell Efficiency

Synthesis and Nonlinear Optical Studies on Organic Compounds in Laser-Deposited Films

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