Toward Over 15% Power Conversion Efficiency for Organic Solar Cells: Current Status and Perspectives

Zhang, Jianqi; Zhu, Lingyun; Wei, Zhixiang

doi:10.1002/smtd.201700258

Cited by 136 publications

(112 citation statements)

References 158 publications

(239 reference statements)

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“…While the PCE of these BHJ devices are relatively low (~10%), devices composed solely of all polymeric (nonfullerene) and all nonpolymeric small molecules have demonstrated further improvements in PCE. For instance, engineering tandem structures consisting of double‐BHJ active layers has resulted in a PCE of ~15% . The PCE of OSCs based on BHJ active layer depends on the morphology as well as on the intermolecular interactions between the donor and the acceptor molecules .…”

Section: Introductionmentioning

confidence: 99%

Effect of polydispersity on the bulk‐heterojunction morphology of P3HT:PCBM solar cells

Munshi

Ghumman

Iyer

et al. 2019

J Polym Sci B Polym Phys

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Bulk heterojunctions (BHJs) based on semiconducting electron–donor polymer and electron–acceptor fullerene have been extensively investigated as potential photoactive layers for organic solar cells (OSCs). In the experimental studies, poly‐(3‐hexyl‐thiophene) (P3HT) polymers are hardly monodisperse as the synthesis of highly monodisperse polymer mixture is a near impossible task to achieve. However, the majority of the computational efforts on P3HT: phenyl‐C61‐butyric acid methyl ester (P3HT:PCBM)‐based OSCs, a monodisperse P3HT is usually considered. Here, results from coarse‐grained molecular dynamics simulations of solvent evaporation and thermal annealing process of the BHJ are shared describing the effect of variability in molecular weight (also known as polydispersity) on the morphology of the active layer. Results affirm that polydispersity is beneficial for charge separation as the interfacial area is observed to increase with higher dispersity. Calculations of percolation and orientation tensors, on the other hand, reveal that a certain polydispersity index ranging between 1.05 and 1.10 should be maintained for optimal charge transport. Most importantly, these results point out that the consideration of polydispersity should be considered in computational studies of polymer‐based OSCs. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 895–903

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Section: Introductionmentioning

confidence: 99%

Effect of polydispersity on the bulk‐heterojunction morphology of P3HT:PCBM solar cells

Munshi

Ghumman

Iyer

et al. 2019

J Polym Sci B Polym Phys

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“…[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.…”

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...

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“…PTB7 [−5.14 eV] and P3HT [−5.2 eV]). It can be explained by the low E loss (energy loss) of PTB7: Flu‐CNRH (0.48 eV) compared to that of P3HT: Flu‐CNRH (1.09 eV), where E loss can be defined as E loss = E g − e V OC , where E g is the lowest optical bandgap of the donor or acceptor component …”

Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of a 2‐(1,1‐Dicyanomethylene) rhodanine‐based Nonfullerene Acceptor for OPVs

Koh

Lim

2018

Bulletin Korean Chem Soc

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We synthesized an A–π–D–π–A‐type nonfullerene small molecule acceptor (Flu‐CNRH) based on fluorene and 2‐(1,1‐dicyanomethylene)rhodanine (CNRH) by a Knoevenagel condensation of the diformyl compound (Flu‐T‐CHO) and CNRH for the use as acceptors in organic photovoltaic cells (OPVs). Introduction of CNRH end groups effectively lowered the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels of the acceptor compared to those of the corresponding rhodanine‐based acceptor (Flu‐RH). The HOMO and LUMO levels of Flu‐CNRH are −5.71 and −3.60 eV, respectively. For comparison, Flu‐RH has HOMO and LUMO energy levels of −5.58 and −3.53 eV, respectively. This lowered LUMO energy level enables Flu‐CNRH to be combined with low bandgap polymer donors PTB7 and PTB7‐Th by providing proper LUMO offsets between donor and acceptor. OPV cells were fabricated with the device configuration of ITO/PEDOT:PSS/active layer/LiF/Al. The best power conversion efficiency of 1.47% was obtained in the P3HT:Flu‐CNRH devices at a D:A ratio of 1:1.5 and with annealing at 140°C. Moreover, Flu‐CNRH showed compatibility with low bandgap polymer donor PTB7 (1.22%) with external quantum efficiency response at a longer wavelength region up to 750 nm, while Flu‐RH had no photovoltaic behavior with PTB7 and PTB7‐Th.

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Toward Over 15% Power Conversion Efficiency for Organic Solar Cells: Current Status and Perspectives

Cited by 136 publications

References 158 publications

Effect of polydispersity on the bulk‐heterojunction morphology of P3HT:PCBM solar cells

Effect of polydispersity on the bulk‐heterojunction morphology of P3HT:PCBM solar cells

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

Synthesis and Characterization of a 2‐(1,1‐Dicyanomethylene) rhodanine‐based Nonfullerene Acceptor for OPVs

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