Molecular Lock: A Versatile Key to Enhance Efficiency and Stability of Organic Solar Cells

Cheng, Pei; Yan, Cenqi; Lau, Tsz‐Ki; Mai, Jiangquan; Lu, Xinhui; Zhan, Xiaowei

doi:10.1002/adma.201600426

Cited by 143 publications

(119 citation statements)

References 70 publications

(76 reference statements)

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“…It is generally accepted that DIO with a high boiling point tends to reside in active layer, underwent a sharp decrease in thermal stability of many heterojunction systems . Surprisingly, the BT solvent additive is much superior to DIO, leading to significant improvement in thermal stability.…”

Section: Resultsmentioning

confidence: 99%

“…The low band gap polymers such as poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b;4,5‐b′]dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b]thiophene‐)‐2‐carboxylate‐2‐6‐diyl)] (PTB7‐Th) is known for its high performance after blending with PC 71 BM . Anyway, low band gap polymers are sensitive to heat and are thermally unstable . In these systems, 1,8‐diiodooctane (DIO) is one of the widely used and efficient solvent additive to improve PCE value, but it has a deleterious effect on thermal stability .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Improved Glass Transition Temperature towards Thermal Stability via Thiols Solvent Additive versus DIO in Polymer Solar Cells

Yin

Zhou

Zhang

et al. 2017

Macromol. Rapid Commun.

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The halogen-free solvent additive, 1,4-butanedithiol (BT) has been incorporated into PTB7-Th:PC BM, leading to higher power conversion efficiency (PCE) value as well as substantially enhanced thermal stability, as compared with the traditional 1,8-diiodooctane (DIO) additive. More importantly, the improved thermal stability after processing with BT contributes to a higher glass transition temperature (T ) of PTB7-Th, as determined by dynamic mechanical analysis. After thermal annealing at 130 °C in nitrogen atmosphere for 30 min, the PCE of the specimen processed with BT reduces from 9.3% to 7.1%, approaching to 80% of its original value. In contrast, the PCE of specimens processed with DIO seriously depresses from 8.3% to 3.8%. These findings demonstrate that smart utilization of low-boiling-point solvent additive is an effective and practical strategy to overcome thermal instability of organic solar cells via enhancing the T of donor polymer.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improved Glass Transition Temperature towards Thermal Stability via Thiols Solvent Additive versus DIO in Polymer Solar Cells

Yin

Zhou

Zhang

et al. 2017

Macromol. Rapid Commun.

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“…The optimal morphology in BHJ devices is usually a metastable state and will further move toward a thermodynamic equilibrium state to form phase separation, leading to deterioration of lifetime and performance of OSCs. Based on this view, a lot of methods are carried out to control the morphology and to further enhance the performance of OSCs . However, these approaches are generally limited to the specific materials and photovoltaic systems; therefore, it is necessary to develop a more universal and facile fabrication process to solve above problems and as well as to improve the stature of OSCs.…”

Section: Detailed Photovoltaic Parameters Of Blade‐coated Oscs Under mentioning

confidence: 99%

Sequential Blade‐Coated Acceptor and Donor Enables Simultaneous Enhancement of Efficiency, Stability, and Mechanical Properties for Organic Solar Cells

Wang

Zhu

Naveed

et al. 2020

Advanced Energy Materials

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As a predominant fabrication method of organic solar cells (OSCs), casting of a bulk heterojunction (BHJ) structure presents overwhelming advantages for achieving higher power conversion efficiency (PCE). However, long‐term stability and mechanical strength are significantly crucial to realize large‐area and flexible devices. Here, controlling blend film morphology is considered as an effective way toward co‐optimizing device performance, stability, and mechanical properties. A PCE of 12.27% for a P‐i‐N‐structured OSC processed by sequential blade casting (SBC) is reported. The device not only outperforms the as‐cast BHJ devices (11.01%), but also shows impressive stability and mechanical properties. The authors corroborate such enhancements with improved vertical phase separation and purer phases toward more efficient transport and collection of charges. Moreover, adaptation of SBC strategy here will result in thermodynamically favorable nanostructures toward more stable film morphology, and thus improving the stability and mechanical properties of the devices. Such co‐optimization of OSCs will pave ways toward realizing the highly efficient, large‐area, flexible devices for future endeavors.

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“…[26][27][28] To make organic photovoltaics commercially viable and competitive, researchers have been making efforts on characterizing, understanding, and rationally engineering the long-term stability of OSC devices. [26,[29][30][31][32][33][34][35][36][37][38] Generally, the performance degradation of OSCs comes from the oxidation of electrodes, degradation of the interface layers, and changes in the morphology of the active layer. Among these factors, the oxidation of electrodes and the degradation of the interface layers are attributed to exposure to oxygen and moisture, [39,40] and these drawbacks can be largely prevented by encapsulation.…”

mentioning

confidence: 99%

Rational Strategy to Stabilize an Unstable High‐Efficiency Binary Nonfullerene Organic Solar Cells with a Third Component

Zhu

Gadisa

Peng

et al. 2019

Advanced Energy Materials

141

143

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decades, heuristic approaches have been successfully used to enhance the performance of OSCs, including synthesis of new donor and acceptor molecules, [5][6][7][8][9][10] optimization of the interface and morphology, [11][12][13][14][15] ternary blending, [16][17][18][19] and device engineering. [20][21][22][23] As a result, power conversion efficiency (PCE) of OSCs has surpassed 15% for single-layer bulkheterojunction systems. [24,25] As the PCE of OSCs is getting closer to the requirements for commercial applications and competing technology, the most efficient OSCs also need to perform consistently or maintain low efficiency loss throughout their lifetimes. [26][27][28] To make organic photovoltaics commercially viable and competitive, researchers have been making efforts on characterizing, understanding, and rationally engineering the long-term stability of OSC devices. [26,[29][30][31][32][33][34][35][36][37][38] Generally, the performance degradation of OSCs comes from the oxidation of electrodes, degradation of the interface layers, and changes in the morphology of the active layer. Among these factors, the oxidation of electrodes and the degradation of the interface layers are attributed to exposure to oxygen and moisture, [39,40] and these drawbacks can be largely prevented by encapsulation. [41,42] However, the intrinsic instability of active layer morphology driven by light, temperature, and thermodynamics cannot be prevented by encapsulation. In-depth studies were carried out to understand the stability of the active layers under multiple stresses. [43] For instance, McGehee and co-workers [29] reported that solar cells based on amorphous materials would suffer from open-circuit voltage (V OC ) burnin degradation resulted from the impact of light-induced traps, and this degradation can be reduced by using materials with high degree of crystallinity. Brabec group [33] demonstrated that the light-induced [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) dimerization would lead to the short-circuit current density (J SC ) loss after aging, while this dimerization can be inhibited by a high degree of polymer-fullerene mixing and it can also be reduced via increasing the crystallization of the fullerene domains. Brabec and co-workers [34] found that burnin degradation driven by low miscibility is the major short-time Long device lifetime is still a missing key requirement in the commercialization of nonfullerene acceptor (NFA) organic solar cell technology. Understanding thermodynamic factors driving morphology degradation or stabilization is correspondingly lacking. In this report, thermodynamics is combined with morphology to elucidate the instability of highly efficient PTB7-Th:IEICO-4F binary solar cells and to rationally use PC 71 BM in ternary solar cells to reduce the loss in the power conversion efficiency from ≈35% to <10% after storage for 90 days and at the same time improve performance. The hypomiscibility observed for IEICO-4F in PTB7-Th (below the percolation threshold) leads to overpurific...

show abstract

Molecular Lock: A Versatile Key to Enhance Efficiency and Stability of Organic Solar Cells

Cited by 143 publications

References 70 publications

Improved Glass Transition Temperature towards Thermal Stability via Thiols Solvent Additive versus DIO in Polymer Solar Cells

Improved Glass Transition Temperature towards Thermal Stability via Thiols Solvent Additive versus DIO in Polymer Solar Cells

Sequential Blade‐Coated Acceptor and Donor Enables Simultaneous Enhancement of Efficiency, Stability, and Mechanical Properties for Organic Solar Cells

Rational Strategy to Stabilize an Unstable High‐Efficiency Binary Nonfullerene Organic Solar Cells with a Third Component

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