Dithienopicenocarbazole-Based Acceptors for Efficient Organic Solar Cells with Optoelectronic Response Over 1000 nm and an Extremely Low Energy Loss

Yao, Zhaoyang; Liao, Xunfan; Gao, Ke; Lin, Francis; Xu, Xiaobao; Shi, Xueliang; Zuo, Lijian; Liu, Feng; Chen, Yiwang; Jen, Alex K.‐Y.

doi:10.1021/jacs.7b13239

Cited by 377 publications

(263 citation statements)

References 44 publications

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“…[38][39][40][41][42][43][44] Current research shows that NFA OSCs can provide decent PCEs with ΔE HOMO low to 0 eV. This has become a significant advantage of NFA-based OSCs compared with fullerene-based OSCs, that is, ΔE HOMO modulation may effectively manage the V oc -short-circuit current (J sc ) trade-off.…”

Section: Introductionmentioning

confidence: 99%

Accurate Determination of the Minimum HOMO Offset for Efficient Charge Generation using Organic Semiconducting Alloys

Zhang

Liu

Zhou

et al. 2019

Advanced Energy Materials

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reveal the bright future of this greenenergy technology. [1][2][3] Exciton dissociation into free charges is the most important optoelectronic process, which is driven by the energy-level difference between donor and acceptor materials. [4,5] For OSCs utilizing fullerene derivatives as electron acceptors, a lowest unoccupied molecular orbital (LUMO) offset [ΔE LUMO = E LUMO(D) − E LUMO(A) ] of no less than 0.30 eV was generally proposed to guarantee efficient electron transfer. [6][7][8] However, this leads to large energy losses (>0.60 eV), as defined by E loss = E g opt − qV oc , (E g opt is the optical bandgap, V oc is the open-circuit voltage, and q is elementary charge), and limits the power conversion efficiency (PCE) to less than 12% [9][10][11][12][13][14] after decades of effort. Thus far, the development of donor (D)-acceptor (A)-type nonfullerene molecular acceptors (NFAs) with well-tunable electronic structures has opened up a great opportunity in this active topic because these NFAs have realized high PCEs over 15%. [15][16][17][18][19][20][21] To form a complementary absorption, current popular NFA OSCs are based on the combination of a widebandgap donor and a narrow-bandgap acceptor. [22][23][24][25][26][27][28][29][30][31][32][33] For such a material combination, a large ΔE LUMO always exists, which reduces the highest occupied molecular orbital (HOMO) offset [ΔE HOMO = E HOMO(D) − E HOMO(A) ] to minimize energy loss [34][35][36][37] while enhancing the light collection in near-infrared (NIR) Current research indicates that exciton dissociation into free charge carriers can be achieved in material combinations with the highest occupied molecular orbital (HOMO) offset lowered to 0 eV in non-fullerene organic solar cells. However, the quantitative relationship between the HOMO offset and exciton dissociation has not been established because of the difficulty inachieving continuously tunable HOMO offsets. Here, the binary blends of PTQ10:ZITI-S and PTQ10:ZITI-N are combined to form the positive and negative HOMO offsets of 0.20 and −0.07 eV, respectively. While the PTQ10:ZITI-S binary blend delivers a decent power conversion efficiency (PCE) of 10.69% with a shortcircuit current (J sc ) of 16.94 mA cm −2 , the PTQ10:ZITI-N with the negative offset shows a much lower PCE of 7.06% mainly because of the low J sc of 12.03 mA cm −2 . Because the tunable HOMO levels can be realized in organic semiconducting alloys based on ZITI-N and ZITI-S acceptors, the transformation of the HOMO energy offset from negative to positive values is achieved in the PTQ10:ZITIN:ZITI-S ternary blends, delivering much-improved PCEs up to 13.26% with a significant, 74% enhancement of J sc to 20.93 mA cm −2 .With detailed investigations, the study reveals that the minimum HOMO offset of ≈40 meV is required to achieve the most-efficient exciton dissociation and photovoltaic performance.

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Section: Introductionmentioning

confidence: 99%

Accurate Determination of the Minimum HOMO Offset for Efficient Charge Generation using Organic Semiconducting Alloys

Zhang

Liu

Zhou

et al. 2019

Advanced Energy Materials

Self Cite

104

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“…The main difference between the “D” and “A” units is that “A” units possess highly electronegative element such as oxygen in carbonyl or cyano (CN) groups. A strong fused donating unit with strong acceptor unit can produce FREAs with extremely narrow bandgap …”

Section: Osc Parameters and Architecturementioning

confidence: 99%

“…Recently, Jen and co‐workers developed FREAs, where perylene was modified with a carbazole to form the DTPC core . The core was end‐capped by DCI and DFIC units to form DTPC‐IC and DTPC‐DFIC ( A56 , Figure ), respectively.…”

Section: Nfas and Various Aspects Of Freasmentioning

confidence: 99%

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

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2019

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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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“…The universal strategy for construction of more electron‐rich fused ring core units is introducing electron‐donating side‐chain or extending core size by aromatic heterocycle. Utilization of more electron‐rich fused ring core units can achieve narrow bandgap NF‐SMAs with the optical absorption toward NIR region, which is one of ideal case for improving the PCE of the NF‐SMAs based PSC . However, the electron‐rich fused ring core units for high performance NF‐SMAs are still limited due to relative complicated synthetic route, which impede the development of NF‐SMAs based PSCs.…”

Section: Introductionmentioning

confidence: 99%

Effects of the Number of Bromine Substitution on Photovoltaic Efficiency and Energy Loss of Benzo[1,2‐b:4,5‐b′]diselenophene‐based Narrow‐Bandgap Multibrominated Nonfullerene Acceptors

et al. 2018

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In this work, three near‐infrared (NIR) absorption nonfullerene small‐molecule acceptors (NF‐SMAs) (BDSeIC, BDSeIC2Br, and BDSeIC4Br) based on a fused benzo[1,2‐b:4,5‐b′]diselenophene unit as the electron‐rich central core and 2‐(2,3‐dihydro‐3‐oxo‐1H‐inden‐1‐ylidene)propanedinitrile (INCN) without or with one or two bromine substituents as the electron‐deficient group have been synthesized for polymer solar cells. Compared to BDSeIC without bromine substitution, these multibrominated materials BDSeIC2Br and BDSeIC4Br exhibit lower energy levels, stronger absorption in the range of 500–900 nm, better crystalline quality, and enhanced electron mobility. The optimal BDSeIC2Br‐based devices with PM6 as the donor, achieved a high power conversion efficiency (PCE) of up to 12.5% with a relatively low energy loss (Eloss) of 0.52 eV. The PCE of 12.5% for the BDSeIC2Br‐based devices are much higher than those devices based on PM6:BDSeIC (7.1%) or PM6:BDSeIC4Br (9.6%) blend films, and it is the highest reported PCE in binary PSCs with the brominated INCN end‐capped NF‐SMAs. Such outstanding PCE of BDSeIC2Br‐based device is attributed to more balanced electron/hole mobility, higher charge dissociation and charge collection efficiency, and more proper phase separation features. These results indicate that introducing a benzo[1,2‐b:4,5‐b′]diselenophene core unit and bromine substiution on the end groups is an effective way to achieve high‐performance NIR absorption NF‐SMAs.

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Dithienopicenocarbazole-Based Acceptors for Efficient Organic Solar Cells with Optoelectronic Response Over 1000 nm and an Extremely Low Energy Loss

Cited by 377 publications

References 44 publications

Accurate Determination of the Minimum HOMO Offset for Efficient Charge Generation using Organic Semiconducting Alloys

Accurate Determination of the Minimum HOMO Offset for Efficient Charge Generation using Organic Semiconducting Alloys

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

Effects of the Number of Bromine Substitution on Photovoltaic Efficiency and Energy Loss of Benzo[1,2‐b:4,5‐b′]diselenophene‐based Narrow‐Bandgap Multibrominated Nonfullerene Acceptors

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