Chlorinated Wide-Bandgap Donor Polymer Enabling Annealing Free Nonfullerene Solar Cells with the Efficiency of 11.5%

Liu, Zhitian; Gao, Yerun; Dong, Jun; Yang, Minlang; Liu, Ming; Zhang, Yu; Wen, Jing; Ma, Haibo; Gao, Xiang; Chen, Wei; Shao, M.

doi:10.1021/acs.jpclett.8b03247

Cited by 74 publications

(88 citation statements)

References 48 publications

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“…[ 35 ] Chlorinated materials have also drawn attention due to their lower costs for the synthesis of target materials. [ 38–41 ] In comparison to fluorine and chlorine, very little attention has been paid to bromine in this area of research. Bromine is also a halogen atom and demonstrates a strong electronegativity and noncovalent interactions.…”

Section: Methodsmentioning

confidence: 99%

“…The BTIC‐2Br‐ m ‐based device exhibited a slightly higher V oc (0.88 V) compared with that of BTIC‐4Br (0.87 V) due to the higher LUMO energy levels. With a more efficient light harvesting, [ 38 ] the J sc of BTIC‐2Br‐ m may be significantly increased, up to 25.03 mA cm −2 . To the best of our knowledge, the PCE obtained in this study (16.11%) had the highest value among the brominated acceptors in binary PSCs.…”

Section: Methodsmentioning

confidence: 99%

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Bromination: An Alternative Strategy for Non‐Fullerene Small Molecule Acceptors

et al. 2020

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The concept of bromination for organic solar cells has received little attention. However, the electron withdrawing ability and noncovalent interactions of bromine are similar to those of fluorine and chlorine atoms. A tetra‐brominated non‐fullerene acceptor, designated as BTIC‐4Br, has been recently developed by introducing bromine atoms onto the end‐capping group of 2‐(3‐oxo‐2,3‐dihydro‐1H‐inden‐1‐ylidene) malononitrile and displayed a high power conversion efficiency (PCE) of 12%. To further improve its photovoltaic performance, the acceptor is optimized either by introducing a longer alkyl chain to the core or by modulating the numbers of bromine substituents. After changing each end‐group to a single bromine, the BTIC‐2Br‐m‐based devices exhibit an outstanding PCE of 16.11% with an elevated open‐circuit voltage of Voc = 0.88 V, one of the highest PCEs reported among brominated non‐fullerene acceptors. This significant improvement can be attributed to the higher light harvesting efficiency, optimized morphology, and higher exciton quenching efficiencies of the di‐brominated acceptor. These results demonstrate that the substitution of bromine onto the terminal group of non‐fullerene acceptors results in high‐efficiency organic semiconductors, and promotes the use of the halogen‐substituted strategy for polymer solar cell applications.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Bromination: An Alternative Strategy for Non‐Fullerene Small Molecule Acceptors

et al. 2020

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“…At the same time, Hou et al designed and synthesized an efficient polymer PBDB-T-2Cl ( Fig. 3 ) from BDT-2Cl and BDD monomers [24] . They found that both fluorination and chlorination would produce nearly the same dihedral angles between the thiophene and BDT unit.…”

Section: Chlorination Of the Side Chain Of Benzodithiophene Unitsmentioning

confidence: 99%

“…Bulk heterojunction (BHJ) polymer solar cells (PSCs), comprising conjugated polymer as electron donor and fullerene or nonfullrene derivatives as electron acceptor, have been drawing extensive attentions because of their advantages of low cost, large-area solution processability, light weight, mechanical flexibility and the great potential for commercial applications [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] . Especially the nonfullerence polymer solar cells have shown a new direction for photovoltaic study due to the rapid development in PCE [21][22][23][24] . Various strategies on molecular design and synthesis for novel donor acceptor (D-A) polymers have been developed to facilitate the intramolecular charge transfer (ICT) [25][26][27][28][29][30] .…”

Section: Introductionmentioning

confidence: 99%

Chlorination strategy on polymer donors toward efficient solar conversions

Chao

Johner

Zhong

et al. 2019

Journal of Energy Chemistry

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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...

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Chlorinated Wide-Bandgap Donor Polymer Enabling Annealing Free Nonfullerene Solar Cells with the Efficiency of 11.5%

Cited by 74 publications

References 48 publications

Bromination: An Alternative Strategy for Non‐Fullerene Small Molecule Acceptors

Bromination: An Alternative Strategy for Non‐Fullerene Small Molecule Acceptors

Chlorination strategy on polymer donors toward efficient solar conversions

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

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