Scattering techniques for mixed donor–acceptor characterization in organic photovoltaics

Chaney, Thomas; Levin, Andrew J.; Schneider, Sebastian; Toney, Michael F.

doi:10.1039/d1mh01219c

Cited by 14 publications

(19 citation statements)

References 62 publications

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“…High crystalline domains are often considered beneficial in aiding charge transport. [ 32 ] Positive correlations between FF and molecular ordering of NFAs has been reported in many non‐fullerene systems. [ 33 ]…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, we plotted FF and J sc in Figure 9c,d as functions of the diffraction peak intensity of π-π stacking of the NFAs, the latter is often related to the relative degree of crystallinity (rDoC). [32] We Small 2022, 18, 2202411 The π-π stacking of the polymer which is mostly face-on with respect to the substrate as depicted here does not mean that the direction of the fibril growth is known in those systems.…”

Section: Discussionmentioning

confidence: 95%

“…[36] Another important morphological aspect is crystallinity, which improves with amount of the plasticizer additive in the investigated films, potentially aiding charge transport across the active layers. [32] Positive correlations between FF and coherence length of small-molecules has been established in many NFA systems. [33] We did not see any obvious trends in the D coh values of π-π stacking with solvent additive.…”

Section: Discussionmentioning

confidence: 99%

“…[40] In addition to domain size and purity, RSoXS as a technique is very helpful in gaining insights into phase volume fraction and molecular orientation. [32,41] Figure 7a,c shows the Lorentz corrected [42] scattering profiles for the F-and Cl-blends, respectively, versus the scattering vector (Q). For RSoXS, the donor-acceptor contrast is dependent on the index of refraction (Figure S8, Supporting Information).…”

Section: Morphology: Resonant Soft X-ray Scatteringmentioning

confidence: 99%

“…To examine how average domain purity changes with solvent additive, the total "or integrated" scattering intensity (TSI) of the RSoXS profiles is commonly used. [32,36,41] Figure 7b,d presents the TSI, where the composition difference between domains (and therefore domain purity) is proportional to square root of TSI. That also can be used to investigate morphological details at the donor-acceptor interfaces.…”

Section: Morphology: Resonant Soft X-ray Scatteringmentioning

confidence: 99%

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High Sensitivity of Non‐Fullerene Organic Solar Cells Morphology and Performance to a Processing Additive

Alqahtani

et al. 2022

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Although solvent additives are used to optimize device performance in many novel non‐fullerene acceptor (NFA) organic solar cells (OSCs), the effect of processing additives on OSC structures and functionalities can be difficult to predict. Here, two polymer‐NFA OSCs with highly sensitive device performance and morphology to the most prevalent solvent additive chloronaphthalene (CN) are presented. Devices with 1% CN additive are found to nearly double device efficiencies to 10%. However, additive concentrations even slightly above optimum significantly hinder device performance due to formation of undesirable morphologies. A comprehensive analysis of device nanostructure shows that CN is critical to increasing crystallinity and optimizing phase separation up to the optimal concentration for suppressing charge recombination and maximizing performance. Here, domain purity and crystallinity are highly correlated with photocurrent and fill factors. However, this effect is in competition with uncontrolled crystallization of NFAs that occur at CN concentrations slightly above optimal. This study highlights how slight variations of solvent additives can impart detrimental effects to morphology and device performance of NFA OSCs. Therefore, successful scale‐up processing of NFA‐based OSCs will require extreme formulation control, a tuned NFA structure that resists runaway crystallization, or alternative methods such as additive‐free fabrication.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Morphology: Resonant Soft X-ray Scatteringmentioning

confidence: 99%

Section: Morphology: Resonant Soft X-ray Scatteringmentioning

confidence: 99%

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High Sensitivity of Non‐Fullerene Organic Solar Cells Morphology and Performance to a Processing Additive

Alqahtani

et al. 2022

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Multiphase Morphology with Enhanced Carrier Lifetime via Quaternary Strategy Enables High‐Efficiency, Thick‐Film, and Large‐Area Organic Photovoltaics

Zhan

Yin

et al. 2022

Advanced Materials

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With the continuous breakthrough of the efficiency of organic photovoltaics (OPVs), their practical applications are on the agenda. However, the thickness tolerance and upscaling in recently reported high‐efficiency devices remains challenging. In this work, the multiphase morphology and desired carrier behaviors are realized by utilizing a quaternary strategy. Notably, the exciton separation, carrier mobility, and carrier lifetime are enhanced significantly, the carrier recombination and the energy loss (Eloss) are reduced, thus beneficial for a higher short‐circuit density (JSC), fill factor (FF), and open‐circuit voltage (VOC) of the quaternary system. Moreover, the intermixing‐phase size is optimized, which is favorable for constructing the thick‐film and large‐area devices. Finally, the device with a 110 nm‐thick active layer shows an outstanding power conversion efficiency (PCE) of 19.32% (certified 19.35%). Furthermore, the large‐area (1.05 and 72.25 cm2) devices with 110 nm thickness present PCEs of 18.25% and 12.20%, and the device with a 305 nm‐thick film (0.0473 cm2) delivers a PCE of 17.55%, which are among the highest values reported. The work demonstrates the potential of the quaternary strategy for large‐area and thick‐film OPVs and promotes the practical application of OPVs in the future.

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Insulator Polymer Matrix Construction on All‐Small‐Molecule Photoactive Blend Towards Extrapolated 15000 Hour T₈₀ Stable Devices

Ma,

Jiang,

Dela Peña

et al. 2024

Advanced Materials

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To boost the stability of all‐small‐molecule (ASM) organic photovoltaic (OPV) blends, an insulator polymer called styrene‐ethylene‐butylene‐styrene (SEBS) as morphology stabilizer is applied into the host system of small molecules BM‐ClEH:BO‐4Cl. Minor addition of SEBS (1 mg/ml in host solution) provides a significantly enhanced T80 value of 15000 hours (extrapolated), surpassing doping‐free (0 mg/ml) and heavy doping (10 mg/ml) counterparts (900 hours, 30 hours). The material reproducibility and cost‐effectiveness of the active layer will not be affected by this industrially available polymer, where the power conversion efficiency (PCE) can be well maintained at 15.02%, which is still a decent value for non‐halogen solvent‐treated ASM OPV. Morphological and photophysical characterizations clearly demonstrate SEBS's pivotal effect on suppressing the degradation of donor molecules and blend film's crystallization/aggregation reorganization, which protects the exciton dynamics effectively. This work pays meaningful attention to the ASM system stability, performs a smart strategy to suppress the film morphology degradation, and releases a comprehensive understanding of the mechanism of device performance reduction.

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Scattering techniques for mixed donor–acceptor characterization in organic photovoltaics

Abstract: The effects of mixing in organic photovoltaics are unclear partly due to challenges in characterization. X-Ray and neutron scattering techniques have been successful in quantifying mixing but meet new challenges with emerging non-fullerene systems.

Cited by 14 publications

References 62 publications

High Sensitivity of Non‐Fullerene Organic Solar Cells Morphology and Performance to a Processing Additive

High Sensitivity of Non‐Fullerene Organic Solar Cells Morphology and Performance to a Processing Additive

Multiphase Morphology with Enhanced Carrier Lifetime via Quaternary Strategy Enables High‐Efficiency, Thick‐Film, and Large‐Area Organic Photovoltaics

Insulator Polymer Matrix Construction on All‐Small‐Molecule Photoactive Blend Towards Extrapolated 15000 Hour T₈₀ Stable Devices

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Scattering techniques for mixed donor–acceptor characterization in organic photovoltaics

Abstract: The effects of mixing in organic photovoltaics are unclear partly due to challenges in characterization. X-Ray and neutron scattering techniques have been successful in quantifying mixing but meet new challenges with emerging non-fullerene systems.

Cited by 14 publications

References 62 publications

High Sensitivity of Non‐Fullerene Organic Solar Cells Morphology and Performance to a Processing Additive

High Sensitivity of Non‐Fullerene Organic Solar Cells Morphology and Performance to a Processing Additive

Multiphase Morphology with Enhanced Carrier Lifetime via Quaternary Strategy Enables High‐Efficiency, Thick‐Film, and Large‐Area Organic Photovoltaics

Insulator Polymer Matrix Construction on All‐Small‐Molecule Photoactive Blend Towards Extrapolated 15000 Hour T80 Stable Devices

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Product

Resources

About

Insulator Polymer Matrix Construction on All‐Small‐Molecule Photoactive Blend Towards Extrapolated 15000 Hour T₈₀ Stable Devices