Energy-level modulation of non-fullerene acceptors to achieve high-efficiency polymer solar cells at a diminished energy offset

Zhang, Zhongqiang; Liu, Wenqing; Rehman, Tahir; Ju, Huanxin; Mai, Jiangquan; Lu, Xinhui; Shi, Minmin; Zhu, Junfa; Li, Chang‐Zhi; Chen, Hongzheng

doi:10.1039/c7ta01554b

Cited by 83 publications

(47 citation statements)

References 53 publications

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“…However, the minimal sufficient value of this energetic offset is constantly being updated. Especially with the emergence of nonfullerene acceptors, quantitative study of the driving forces of exciton dissociation has become a hot research topic . Exciton dissociation at the donor‐acceptor interface generally results in a bound charge‐transfer state (CTS), in which the electron and hole are spatially bound to the acceptor and donor.…”

Section: Working Mechanism and Performance Metricsmentioning

confidence: 99%

Near‐infrared organic photoelectric materials for light‐harvesting systems: Organic photovoltaics and organic photodiodes

Xie

Chen

Ying

et al. 2019

InfoMat

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The inherent advantages of organic optoelectronic materials endow lightharvesting systems, including organic photovoltaics (OPVs) and organic photodiodes (OPDs), with multiple advantages, such as low-cost manufacturing, light weight, flexibility, and applicability to large-area fabrication, make them promising competitors with their inorganic counterparts. Among them, nearinfrared (NIR) organic optoelectronic materials occupy a special position and have become the subject of extensive research in both academia and industry.The introduction of NIR materials into OPVs extends the absorption spectrum range, thereby enhancing the photon-harvesting ability of the devices, due to which they have been widely used for the construction of semitransparent solar cells with single-junction or tandem architectures. NIR photodiodes have tremendous potential in industrial, military, and scientific applications, such as remote control of smart electronic devices, chemical/biological sensing, environmental monitoring, optical communication, and so forth. These practical and potential applications have stimulated the development of NIR photoelectric materials, which in turn has given impetus to innovation in light-harvesting systems. In this review, we summarize the common molecular design strategies of NIR photoelectric materials and enumerate their applications in OPVs and OPDs. K E Y W O R D Snear infrared, organic optoelectronic materials, organic photodiodes, organic photovoltaics

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Section: Working Mechanism and Performance Metricsmentioning

confidence: 99%

Near‐infrared organic photoelectric materials for light‐harvesting systems: Organic photovoltaics and organic photodiodes

Xie

Chen

Ying

et al. 2019

InfoMat

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“…As a comparison, PBDB‐T:ITIC based devices exhibited a voltage of 0.93 V and a PCE of 10.6%. Chen and Li et al incorporated thiophene bridge between the electron‐donating part and electron‐withdrawing part of ITIC to tune the energy levels (ITTIC) . This change simultaneously lifted both HOMO and LUMO levels, while narrowing its optical bandgap.…”

Section: High‐performance Oscs With Non‐fullerene Acceptorsmentioning

confidence: 99%

Efficient Organic Solar Cells with Non‐Fullerene Acceptors

Liu

et al. 2017

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Fullerene-free OSCs employing n-type small molecules or polymers as the acceptors have recently experienced a rapid rise with efficiencies exceeding 12%. Owing to the good optoelectronic and morphological tunabilities, non-fullerene acceptors exhibit great potential for realizing high-performance and practical OSCs. In this Review, recent exciting progress made in developing highly efficient non-fullerene acceptors is summarized, mainly correlating factors like absorption, energy loss and morphology of new materials to their correspondent photovoltaic performance.

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“…[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. [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) [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.…”

mentioning

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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Energy-level modulation of non-fullerene acceptors to achieve high-efficiency polymer solar cells at a diminished energy offset

Abstract: A non-fullerene acceptor ITTIC is developed for polymer solar cells with a donor polymer PBDB-T1. A high PCE of 9.12% was obtained with an energy loss of 0.54 eV at a diminished donor/acceptor energy offset.

Cited by 83 publications

References 53 publications

Near‐infrared organic photoelectric materials for light‐harvesting systems: Organic photovoltaics and organic photodiodes

Near‐infrared organic photoelectric materials for light‐harvesting systems: Organic photovoltaics and organic photodiodes

Efficient Organic Solar Cells with Non‐Fullerene Acceptors

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

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