Achieving High‐Performance Ternary Organic Solar Cells through Tuning Acceptor Alloy

Chen, Yu‐Sheng; Ye, Pan; Zhu, Zhen‐Gang; Wang, Xinlong; Yang, Lei; Xu, Xiaolong; Wu, Xiaoxi; Dong, Tao; Zhang, Hao; Hou, Jianhui; Liu, Feng; Huang, Hui

doi:10.1002/adma.201603154

Cited by 175 publications

(130 citation statements)

References 36 publications

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“…As observed from Figure 2 and Table 1, the PTB7-Th:PC 70 BM presented a PCE value of 8.8%, a V oc of 0.782 V, J sc of 16.54 mA cm −2 , and FF of 67.2%, respectively. These results are similar to those reported by other research groups, [31,40,54] suggesting that the incorporation of crystalline molecule could facilitate the fabrication of PTB7-Th:PC 70 BM-based devices with thick active layer suitable for large-area printing. A similar trend of FF change versus DRCN5T ratio was also observed.…”

Section: Resultssupporting

confidence: 91%

“…[25] Although both ternary OSCs and tandem OSCs could improve the power conversion efficiency (PCE) value to about 15%, the ternary strategy possessing simplicity of processing active layer exhibits great potential in R2R technology. [29] Especially, many researchers have realized the importance of miscibility in ternary OSCs, [28,[35][36][37] such as the appearance of Förster resonance energy transfer, [38] distribution of third additive on the interfaces of donor and acceptor, [39] formation of alloy with donor or acceptor, [36,37,40] etc. [6,[32][33][34] Unfortunately, most of the research work about how to select appropriate third additive is based on the trial and error strategy, which is a process of labor and time consumption.…”

Section: Introductionmentioning

confidence: 99%

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Miscibility Tuning for Optimizing Phase Separation and Vertical Distribution toward Highly Efficient Organic Solar Cells

et al. 2019

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Blending multidonor or multiacceptor organic materials as ternary devices has been recognized as an efficient and potential method to improve the power conversion efficiency of bulk heterojunction devices or single‐junction components in tandem design. In this work, a highly crystalline molecule, DRCN5T, is involved into a PTB7‐Th:PC 70 BM system to fabricate large‐area organic solar cells (OSCs) whose blend film thickness is up to 270 nm, achieving an impressive performance of 11.1%. The significant improvement of OSCs after adding DRCN5T is due to the formation of an interconnected fibrous network with decreased π–π stacking and enhanced domain purity, in addition to the optimized vertical distribution of PTB7‐Th and PC 70 BM, producing more effective charge separation, transport, and collection. The optimized morphology and performance are actually determined by the miscibility in different components, which can be quantitatively described by the Flory–Huggins interaction parameter of −0.80 and 2.94 in DRCN5T:PTB7‐Th and DRCN5T:PC 70 BM blends, respectively. The findings in this work can potentially guide the selection of an appropriate third additive for high‐performance OSCs for the sake of large‐area printing and roll‐to‐roll fabrication from the view of miscibility.

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Miscibility Tuning for Optimizing Phase Separation and Vertical Distribution toward Highly Efficient Organic Solar Cells

et al. 2019

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“…Based on the morphological analysis, it is clearly demonstrated that the ternary morphology stabilization originates from two important elements. [78] Zhan and co-workers. Second, the suppression of the IEICO-4F crystals in the aged ternary devices, unlike in the binary blend, is an indication that the PC 71 BM dispersion in IEICO-4F is highly stable, and we attribute this to formation of acceptor alloys, which provide additional entropy.…”

Section: Discussionmentioning

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

139

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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...

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“…As will be detailed later, the interfacial tension between two organic molecules has been demonstrated to correlate with the extent of mixing. [15,22,63,[71][72][73][74] Second, the FF of the devices increases first and then drops with increasing IEIC-Th content. There are a few clear trends in the J-V characteristics of the PTFB-O:ITIC-Th:IEIC-Th ternary devices.…”

Section: Ternary Blend Design and Photovoltaic Device Performancementioning

confidence: 97%

“…[11,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] However, one main constraint that slows down the development of ternary OSC is the difficulty in controlling the morphology of ternary blends. To maintain the simplicity of the single junction structure and in the meantime broaden the absorption range of the solar cell, ternary OSCs have been developed where two donors and one acceptor or one donor and two acceptors are blended together to form the active layer.…”

mentioning

confidence: 99%

Multiple Cases of Efficient Nonfullerene Ternary Organic Solar Cells Enabled by an Effective Morphology Control Method

Jiang

Zhang

Yang

et al. 2017

Advanced Energy Materials

147

114

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of multijunction architecture increases the absorption breadth of a solar cell device, the difficulty of device fabrication and therefore the cost for large-scale production are significantly raised. To maintain the simplicity of the single junction structure and in the meantime broaden the absorption range of the solar cell, ternary OSCs have been developed where two donors and one acceptor or one donor and two acceptors are blended together to form the active layer. Important advances have been realized for ternary OSCs with best PCEs reaching beyond 10%. [11,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] However, one main constraint that slows down the development of ternary OSC is the difficulty in controlling the morphology of ternary blends. It is commonly accepted that the bulk-heterojunction (BHJ) morphology for a two-component system is already complex. [25,[30][31][32][33][34] A threephase model has been generally utilized to describe the complicated morphology where a relatively pure donor phase, a relatively pure acceptor phase, and a intermixed donor:acceptor phase coexist in the active medium. [35][36][37][38][39][40][41][42] Apparently, the morphology formed by ternary blends would be even more challenging to evaluate. Due to the absence of effective methods to control the morphology, most of the previous reports on ternary OSCs only focused on one single material combination, Ternary organic solar cells (OSCs) have attracted much research attention, as they can maintain the simplicity of the single-junction device architecture while broadening the absorption range of OSCs. However, one main challenge that limits the development of ternary OSCs is the difficulty in controlling the morphology of ternary OSCs. In this paper, an effective approach to control the morphology is presented that leads to multiple cases of efficient nonfullerene ternary OSCs with efficiencies of up to 11.2%. This approach is based on a donor polymer with strong temperature dependent aggregation properties processed from hot solutions without any solvent additives and a pair of small molecular acceptors (SMAs) that have similar surface tensions and thus low propensity to form discrete phases. Such a ternary blend exhibits a simplified bulk-heterojunction morphology that is similar to the morphology of previously reported binary blends. As a result, an almost linear relationship between V OC and film composition is observed for all nonfullerene ternary devices. Meanwhile, by carefully designing a control system with a large interfacial tension, a different phase separation and V OC dependence is demonstrated. This morphology control approach can be applicable to more material systems and accelerates the development of the ternary OSC field.

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Achieving High‐Performance Ternary Organic Solar Cells through Tuning Acceptor Alloy

Cited by 175 publications

References 36 publications

Miscibility Tuning for Optimizing Phase Separation and Vertical Distribution toward Highly Efficient Organic Solar Cells

Miscibility Tuning for Optimizing Phase Separation and Vertical Distribution toward Highly Efficient Organic Solar Cells

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

Multiple Cases of Efficient Nonfullerene Ternary Organic Solar Cells Enabled by an Effective Morphology Control Method

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