The progress of non-fullerene small molecular acceptors for high efficiency polymer solar cells

Li, Hao; Wang, Jiuxing; Wang, Yao; Bu, Fanchen; Shen, Wenfei; Liu, Jixian; Huang, Linjun; Wang, Wei; Belfiore, Laurence A.; Tang, Jianguo

doi:10.1016/j.solmat.2018.10.016

Cited by 33 publications

(20 citation statements)

References 107 publications

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“…Compared with fullerene derivatives, these NFAs can be readily synthesized, making it easier to control the energy levels of the molecules and the morphologies of the films . NFAs can be designed to have appropriate energy level alignment with the donor materials, resulting in relatively low energy loss ( E loss ), and/or to absorb photons in the UV–vis region complementary to the donor material absorption spectrum, thereby increasing device efficiency by absorbing a broad spectrum in the active layer …”

Section: Introductionmentioning

confidence: 99%

“…Later, the aromatic π systems of electron‐rich cores were extended to form penta‐, hepta‐, and even decacyclic fused rings. Representative fused ring cores used to construct the high‐performance NFAs are indacenodithiophene (IDT, pentacyclic ring)[3b,11b,13] and indacenodithienothiophene (IDTT, heptacyclic ring). [2a,8b,14] Recently, more complex and extended ladder‐type cores, including indacenothiophenethiophene‐ alt ‐dithienothiophene (IDT8, asymmetrical octacyclic ring), carbon‐oxygen‐bridged three thieno[3,2‐ b ]thiophene (CO i 8, octacyclic ring), and a fusion of naphthodithiophene and two thienothiophene moieties (IDC, decacyclic ring) have been reported to provide high‐performance (>12%) acceptors .…”

Section: Introductionmentioning

confidence: 99%

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Simple Bithiophene–Rhodanine‐Based Small Molecule Acceptor for Use in Additive‐Free Nonfullerene OPVs with Low Energy Loss of 0.51 eV

Lee

Eom

Song

et al. 2019

Advanced Energy Materials

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The introduction of rigid and extended ladder‐type fused‐ring cores, such as indacenodithiophene, has enabled the synthesis of a variety of nonfullerene small molecules for use as electron acceptors in high‐performance organic photovoltaic cells. Contrasting with recent trends, a very simple‐structured nonfullerene acceptor (NFA), T2‐ORH, consisting of a bithiophene core and octyl‐substituted rhodanine ends, is synthesized in two steps from inexpensive commercially available raw materials. Its relatively short π‐conjugation results in a wide bandgap and a blue‐shifted UV–vis absorption profile complementary to those of poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene‐co‐3‐fluorothieno[3,4‐b]thiophene‐2‐carboxylate] (PTB7‐Th). Despite a sufficient offset between T2‐ORH and PTB7‐Th, the lowest unoccupied molecular orbital (LUMO) energy level of T2‐ORH is still higher than the LUMOs of other NFAs (e.g., ITIC). Therefore, the PTB7‐Th:T2‐ORH blend film exhibits an efficiency of 9.33% with a high open‐circuit voltage of 1.07 V and a short‐circuit current of 14.72 mA cm−2 in an additive‐free single‐junction cell. Importantly, the optimized device displays a remarkably low energy loss of 0.51 eV, in which bimolecular and monomolecular charge recombination is effectively suppressed by solvent vapor annealing treatment. The blend film has a very smooth and homogeneous morphology, providing both vertical and parallel charge transport in the devices.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Simple Bithiophene–Rhodanine‐Based Small Molecule Acceptor for Use in Additive‐Free Nonfullerene OPVs with Low Energy Loss of 0.51 eV

Lee

Eom

Song

et al. 2019

Advanced Energy Materials

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“…Even with the significant limitations of FAs, much of the OSC research focused on the development of low bandgap donor materials especially conjugated polymer with broad absorption and fine‐tuning photophysical properties to match FAs. Recently, rapid progress has been made on NFAs especially on FREAs to overcome the challenges described earlier . FREAs offer some distinct advantages.…”

Section: Introductionmentioning

confidence: 99%

Recent Progress in Molecular Design of Fused Ring Electron Acceptors for Organic Solar Cells

Dey

2019

Small

139

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The quest for sustainable energy sources has led to accelerated growth in research of organic solar cells (OSCs). A solution‐processed bulk‐heterojunction (BHJ) OSC generally contains a donor and expensive fullerene acceptors (FAs). The last 20 years have been devoted by the OSC community to developing donor materials, specifically low bandgap polymers, to complement FAs in BHJs. The current improvement from ≈2.5% in 2013 to 17.3% in 2018 in OSC performance is primarily credited to novel nonfullerene acceptors (NFA), especially fused ring electron acceptors (FREAs). FREAs offer unique advantages over FAs, like broad absorption of solar radiation, and they can be extensively chemically manipulated to tune optoelectronic and morphological properties. Herein, the current status in FREA‐based OSCs is summarized, such as design strategies for both wide and narrow bandgap FREAs for BHJ, all‐small‐molecule OSCs, semi‐transparent OSC, ternary, and tandem solar cells. The photovoltaics parameters for FREAs are summarized and discussed. The focus is on the various FREA structures and their role in optical and morphological tuning. Besides, the advantages and drawbacks of both FAs and NFAs are discussed. Finally, an outlook in the field of FREA‐OSCs for future material design and challenges ahead is provided.

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“…Polymer solar cells (PSCs) based on a bulk heterojunction (BHJ) active layer (consists of a blend of donor (D), i.e., p‐type organic semiconductor and acceptor (D), i.e., n‐type semiconductor) have been studied extensively for over two decades, resulting in significant elaborations in both material strategy and device production. [ 1–6 ] After strategic design of the organic semiconducting materials, particularly nonfullerene small molecule acceptor (NFSMA), [ 7–10 ] optimization of device architecture and control of the mixing and phase separation of two or more of these semiconducting material components in the active layer [ 11,12 ] have drastically increased the power conversion efficiency (PCE) in the range of 17–18% using the NFSMA and conjugated polymer donor [ 13–16 ] and can be further improved beyond 20%. [ 17 ]…”

Section: Introductionmentioning

confidence: 99%

Ternary Polymer Solar Cells Using Two Polymers P1 and P3 with Similar Chemical Structures and Nonfullerene Acceptor Attained Power Conversion Efficiency Over 15.5% with Low Energy Loss of 0.55 eV

et al. 2020

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Herein, ternary active layer‐based polymer solar cells using two donor (D)–acceptor (A) conjugated polymers P1 and P3 having same A unit and different D units as donor along with the nonfullerene small molecule acceptor, BThIND‐Cl, are fabricated. The polymer solar cells based on P1:BThIND‐Cl and P3:BThIND‐Cl binary show power conversion efficiency of 12.13% and 13.08% with energy loss of 0.60 and 0.51 eV, respectively. The open circuit voltage of the P3 based polymer solar cells is higher than that for P1 counterpart associated with the deeper highest occupied molecular orbital (HOMO) energy level of P3 as compared to the P1. The small energy loss for P3 may be attributed to low HOMO offset between P3 and BThIND‐Cl. Moreover, the short circuit current density is higher for the P1 based polymer solar cell. Taking the advantages of high valve of short circuit current for P1 and larger value of open circuit voltage for P3 counterpart, optimized polymer solar cells using these two polymers and BThIND‐Cl as acceptor and after the optimization, the polymer solar cells based on P1:P3:BThIND‐Cl showed overall power conversion efficiency of 15.78% with energy loss of 0.55 eV.

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The progress of non-fullerene small molecular acceptors for high efficiency polymer solar cells

Cited by 33 publications

References 107 publications

Simple Bithiophene–Rhodanine‐Based Small Molecule Acceptor for Use in Additive‐Free Nonfullerene OPVs with Low Energy Loss of 0.51 eV

Simple Bithiophene–Rhodanine‐Based Small Molecule Acceptor for Use in Additive‐Free Nonfullerene OPVs with Low Energy Loss of 0.51 eV

Recent Progress in Molecular Design of Fused Ring Electron Acceptors for Organic Solar Cells

Ternary Polymer Solar Cells Using Two Polymers P1 and P3 with Similar Chemical Structures and Nonfullerene Acceptor Attained Power Conversion Efficiency Over 15.5% with Low Energy Loss of 0.55 eV

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