Effects of morphology evolution on solution-processed small molecule photovoltaics via a solvent additive

Hoang, Quoc Viet; Rasool, Shafket; Oh, Sangsuk; Đoán, Vũ Văn; Kim, Da Hun; Lee, Hang Ken; Song, Chang Eun; Lee, Sang Kyu; Lee, Jong‐Cheol; Moon, Sang‐Jin; Shin, Won Suk

doi:10.1039/c7tc02088k

Cited by 15 publications

(11 citation statements)

References 59 publications

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“…This is due to the aggregated donor and acceptor domains, which is in good agreement with the TEM images in Figure 7. [ 63,66 ] From the 1D IP and OP profiles, a broad peak appears at approximately 1.35 Å −1 , which intensifies upon the heating, implying changes in the aggregated domains. This is the reason for the change in photodiode performance upon thermal aging.…”

Section: Resultsmentioning

confidence: 99%

Superior Noise Suppression, Response Time, and Device Stability of Non‐Fullerene System over Fullerene Counterpart in Organic Photodiode

Jang

Rasool

Kim

et al. 2020

Adv Funct Materials

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Herein, non-fullerene acceptor-based organic photodiodes are compared with fullerene acceptor-based organic photodiodes. The non-fullerene acceptor, ethylhexyl-rhodanine-benzothiadiazole-coupled indacenodithiophene (eh-IDTBR)-based organic photodiodes show a higher detectivity (1.61 × 10 13 cm Hz 1/2 W −1) and a faster response time (≈2.7 µs) than the fullerene acceptor, [6,6]-phenyl C 71 butyric acid methyl ester (PC 71 BM)-based organic photodiodes (3.25 × 10 12 cm Hz 1/2 W −1 and ≈6.24 µs, respectively) owing to the excellent dark current suppression of the carrier injection and the low trap density of eh-IDTBR. Moreover, the eh-IDTBR-based photodetector shows better operational device stability than the fullerene counterpart under electrical and thermal stress. This is corroborated by the morphology and crystallography analyses, both of which reveal that the eh-IDTBR-containing photo-sensitive films remain intact after imposing an external stress. This study elucidates important key advantages of the non-fullerene acceptor, eh-IDTBR, and sets a milestone as it compares the non-fullerene acceptors and fullerene acceptors in organic photodiodes for the first time. This work sets a new record for the performance and stability of solution-processable non-fullerene acceptor-based organic photodiodes.

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Section: Resultsmentioning

confidence: 99%

Superior Noise Suppression, Response Time, and Device Stability of Non‐Fullerene System over Fullerene Counterpart in Organic Photodiode

Jang

Rasool

Kim

et al. 2020

Adv Funct Materials

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“…These optimized PCEs demonstrated that molecular donors could compete with their polymer counterparts, provided that an optimal blend morphology is reached. Blends with small molecules that are prone to overcrystallization also respond to solvent additives that prevent early phase separation (i.e., compatibilizers), like 1CN …”

Section: A Brief History Of Solvent Additives In Organic Photovoltaicsmentioning

confidence: 99%

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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“…This increase in the mobility ratio is likely to increase bimolecular recombination and reduce J SC and FF due to the fact there is a smaller fraction of charge carriers being able to escape from the bulk and be collected at the corresponding electrodes. 43,52,53 Morphology of Blend Films. GIWAXS experiments were employed to probe the microstructure and texture of the blend films.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Reassessing the Significance of Reduced Aggregation and Crystallinity of Naphthalene Diimide-Based Copolymer Acceptors in All-Polymer Solar Cells

Đoán

Jevric

Bjuggren

et al. 2022

ACS Appl. Polym. Mater.

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Synthesizing copolymer acceptors based on a mix of three co-monomers is a facile and effective strategy to control the aggregation and crystallinity of semiconducting polymers which has been exploited to improve the photovoltaic performance of all-polymer solar cells (all-PSCs). Applying this strategy to the well-studied electron-transporting polymer acceptor PNDI2OD-T2, different amounts of 3-octylthiophene (OT) are used to partially replace the bithiophene (T2) unit, resulting in three copolymer acceptors PNDI-OTx where x = 5, 10, or 15%. Another polymer, namely PNDI2OD-C8T2, consisting of naphthalene diimide (NDI) polymerized with 3-octyl-2,2′-bithiophene (C8T2) is also synthesized for comparison. It is found that the solution aggregation and thin-film crystallinity of PNDI-OTx are systematically tuned by varying x, evidenced by temperature-dependent UV–vis and grazing incidence wide-angle X-ray scattering measurements. PNDI2OD-C8T2 is also found to have reduced solution aggregation and thin-film crystallinity relative to PNDI2OD-T2. However, the photovoltaic performance of all-PSCs based on J71:PNDI-OTx and J71:PNDI2OD-C8T2 blends are much lower than that of the reference J71:PNDI2OD-T2 system. Extensive morphological studies indicate that reduced aggregation and crystallinity do not guarantee a more favorable blend morphology, with coarser phase separation found in J71:PNDI-OTx and J71:PNDI2OD-C8T2 blends compared to J71:PNDI2OD-T2 blends. Furthermore, the OT-modified copolymers with reduced crystallinity are found to have reduced electron mobilities. The results here suggest that reduced aggregation and less crystallinity of random copolymer acceptors do not always produce favorable morphology in polymer/polymer blends and do not guarantee for improvement in the photovoltaic performance.

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Effects of morphology evolution on solution-processed small molecule photovoltaics via a solvent additive

Abstract: A newly synthesized small molecule donor, BDTT-2DPPBFu, is designed for incorporation into the photo-active layer in solution-processed small molecule organic photovoltaics (SM-OPVs).

Cited by 15 publications

References 59 publications

Superior Noise Suppression, Response Time, and Device Stability of Non‐Fullerene System over Fullerene Counterpart in Organic Photodiode

Superior Noise Suppression, Response Time, and Device Stability of Non‐Fullerene System over Fullerene Counterpart in Organic Photodiode

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

Reassessing the Significance of Reduced Aggregation and Crystallinity of Naphthalene Diimide-Based Copolymer Acceptors in All-Polymer Solar Cells

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