Synergistic effects of solvent and polymer additives on solar cell performance and stability of small molecule bulk heterojunction solar cells

Lee, Hyo-Sang; Ahn, Hyungju; Jo, Jea Woong; Kim, BongSoo; Son, Hae Jung

doi:10.1039/c6ta08278e

Cited by 18 publications

(11 citation statements)

References 49 publications

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“…The P3BT polymer heterogeneously nucleates donor crystallites into interconnected nanofibers, to similar effect as the insulating solid additive PS; however, in this ternary blend, P3BT also contributes to photogeneration and charge transport, increasing the hole mobility by an order of magnitude . Lee et al accomplished similar results by combining 2 wt% PCDTBT with 0.4% v/v DIO in the same D:A blend, synergistically improving performance from 2.4% (without either additive) to 7.9% . Significantly, the ternary blend morphology was less sensitive to thermal treatment and the concentration of solvent additive, as observed for other binary additive combinations .…”

Section: Future Of Solvent Additive Processing In Organic Photovoltaicsmentioning

confidence: 89%

“…In films cast from 3% v/v DIO, overcrystallization could be suppressed by increasing the polymer concentration to 20 wt%—maintaining a PCE of 6.6%, compared to 2.5% without the additional polymer donor. Additionally, Lee et al showed that PCDTBT's ability to nucleate p ‐DTS(FBTTh 2 ) 2 stems from favorable interactions between benzothiadiazole subunits, suggesting future criteria for controlling morphology via ternary components . As a final example, Zhang et al combined 3% v/v DIO with 15 donor wt% p ‐DTS(FBTTh 2 ) 2 as a sensitizer for PTB7‐Th:PC 71 BM blends to achieve 10.5% PCE .…”

Section: Future Of Solvent Additive Processing In Organic Photovoltaicsmentioning

confidence: 99%

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Solvent Additives: Key Morphology‐Directing Agents for Solution‐Processed Organic Solar Cells

et al. 2018

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Organic photovoltaics (OPV) have the advantage of possible fabrication by energy-efficient and cost-effective deposition methods, such as solution processing. Solvent additives can provide fine control of the active layer morphology of OPVs by influencing film formation during solution processing. As such, solvent additives form a versatile method of experimental control for improving organic solar cell device performance. This review provides a brief history of solution-processed bulk heterojunction OPVs and the advent of solvent additives, putting them into context with other methods available for morphology control. It presents the current understanding of how solvent additives impact various mechanisms of phase separation, enabled by recent advances in in situ morphology characterization. Indeed, understanding solvent additives' effects on film formation has allowed them to be applied and combined effectively and synergistically to boost OPV performance. Their success as a morphology control strategy has also prompted the use of solvent additives in related organic semiconductor technologies. Finally, the role of solvent additives in the development of next-generation OPV active layers is discussed. Despite concerns over their environmental toxicity and role in device instability, solvent additives remain relevant morphological directing agents as research interests evolve toward nonfullerene acceptors, ternary blends, and environmentally sustainable solvents.

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Section: Future Of Solvent Additive Processing In Organic Photovoltaicsmentioning

confidence: 89%

Section: Future Of Solvent Additive Processing In Organic Photovoltaicsmentioning

confidence: 99%

Solvent Additives: Key Morphology‐Directing Agents for Solution‐Processed Organic Solar Cells

et al. 2018

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“…[47] Slow solvent evaporation facilitates the formation of interpenetrating donoracceptor networks in the BHJ film. [22,[48][49][50] On the mesoscale, the morphology changes of printed films are tracked by in situ GISAXS measurements. [40,51,52] On this scale, the initial states of liquid solution films on the solid substrate are prone to radiation damage by the intense X-ray beam.…”

Section: (3 Of 7)mentioning

confidence: 99%

In Situ Studies of Solvent Additive Effects on the Morphology Development during Printing of Bulk Heterojunction Films for Organic Solar Cells

et al. 2020

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The development of polymer morphology and crystallinity of printed bulk heterojunction (BHJ) films doped with the different solvent additives 1,8‐diiodooctane (DIO) or diphenyl ether (DPE) is investigated with in situ grazing‐incidence small/wide‐angle X‐ray scattering. The solvent additives, having different boiling points, lead to a different film drying behavior and morphology growth states in the BHJ films of the benzothiadiazole‐based polymer (PPDT2FBT) and [6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM). The phase demixing in the printed films is changing over time along with solvent evaporation. Polymer domains start aggregating to form larger domains in the liquid–liquid phase, while phase separation mainly occurs in the liquid–solid phase. The present work provides a profound insight into the morphology development of printed BHJ films doped with different solvent additives, which is particularly important for the large‐scale fabrication of organic photovoltaics.

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“…Organic molecules with donor‐acceptor (D–A) architect find uses in the area of organic solar cells (OSCs), organic light‐emitting diodes (OLEDs), organic photovoltaics (OPVs), organic thin‐film transistors (OTFTs), two‐photon absorption (2PA), photodynamic therapy, ion‐sensing, cell imaging, fluorescent molecular rotors (FMR's) and non‐linear optical (NLO) materials . Efforts are made to diversify the D–A materials by designing and synthesizing a wide spectrum of dipolar, quadrupolar, octupolar and multi‐branched chromophores .…”

Section: Introductionmentioning

confidence: 99%

N‐Ethyl Carbazole Derived D‐π‐A‐π‐D Based Fluorophores: Consolidated Spectroscopic, Viscosity and DFT Studies

2019

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This article reports design and synthesis of three new fluorophores (5 a‐c) with the donor‐π‐acceptor‐π‐donor motif, where dicyano vinylene group is the central acceptor, N‐ethyl carbazole group is a fixed donor and varying the N‐substituted secondary donors so as to study their photophysical behavior. Based on the systematic photophysical and theoretical reconnaissances, the fluorophores structure‐property relationships are defined. Their spectral and photophysical behaviors are affected by the solvent polarity, with a significant bathochromic shift in emission and large Stoke shifts being observed in polar solvents. Contrary to dipolar asymmetric analogue this system shows an efficient intramolecular charge transfer as observed from various solvent polarity plots. For 5 a, 5 b, and 5 c, the viscosity induced emission studies show respectively 3.78, 6.53, and 6.82 times enhancement in their fluorescence intensity and hence act as a fluorescent molecular rotor (FMR). The structure and electronic properties of these fluorophores were evaluated using density functional theory computations using B3LYP/6‐311++G(d,p). The frontier molecular orbitals and the optimized geometry reveal that secondary donors in each fluorophore donate the electron and not the N‐ethyl carbazole group which is more twisted. The non‐linear and linear optical properties were determined employing solvatochromic and computational methods in solvents of varying polarities with results falling within the expected limiting values. The linear and non‐linear optical properties of the fluorophores change with the strength of different secondary donors used and solvent polarity. The two photon absorption cross‐section described using two level approximation is highest for 5 b (115‐172 GM).

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Synergistic effects of solvent and polymer additives on solar cell performance and stability of small molecule bulk heterojunction solar cells

Abstract: The combination of solvent and polymer additives synergistically enhances solar cell performance and the stability of small molecule bulk heterojunction solar cells.

Cited by 18 publications

References 49 publications

Solvent Additives: Key Morphology‐Directing Agents for Solution‐Processed Organic Solar Cells

Solvent Additives: Key Morphology‐Directing Agents for Solution‐Processed Organic Solar Cells

In Situ Studies of Solvent Additive Effects on the Morphology Development during Printing of Bulk Heterojunction Films for Organic Solar Cells

N‐Ethyl Carbazole Derived D‐π‐A‐π‐D Based Fluorophores: Consolidated Spectroscopic, Viscosity and DFT Studies

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