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Efficient polymeric donor for both visible and near infrared absorbing organic solar cells Vellaiappillai Tamilavan, Yanliang Liu, Jihoon Lee, Insoo Shin, Yun Kyung Jung, Bo Ram Lee, Jung Hyun Jeong, and Sung Heum Park ACS Appl. Energy Mater., Just Accepted Manuscript • DOI: 10.1021/acsaem.9b00520 • Publication Date (Web): 08 May 2019 Downloaded from http://pubs.acs.org on May 8, 2019

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ACS Applied Energy Materials

Efficient polymeric donor for both visible and near infrared absorbing organic solar cells

Vellaiappillai Tamilavan,a,1 Yanliang Liu,a,1 Jihoon Lee,a Insoo Shin, a Yun Kyung Jung,b Bo Ram Lee,a Jung Hyun Jeong,a and Sung Heum Park,*a

aDepartment

of Physics, Pukyong National University, Busan 608-737, Republic of

Korea bSchool

1These

of Biomedical Engineering, Inje University, Gimhae 50834, Republic of Korea

authors made equal contribution to this work.

Correspondence to: S. H. Park (E-mail: [email protected]) Department of Physics, Pukyong National University Busan 608-737, Korea Tel: 82-51-629-5774 Fax: 82-51-629-5549

1 ACS Paragon Plus Environment

ACS Applied Energy Materials 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ABSTRACT:

A

new

ternary

polymer,

TP

ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-bʹ]dithiophene

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incorporating

4,8-bis(5-(2-

(BDTT),

5-octyl-2-(2-

octyldodecyl)-4,6-di(thieno[3,2-b]thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione (PPD), and 2-ethylhexyl 3-fluorothieno[3,4-b]thiophene-2-carboxylate (TT) units at a 2:1:1 ratio was prepared to develop a potential candidate for visible and near infrared (NIR)-absorbing organic solar cells (OSCs). TP displayed an optical bandgap (Eg) of 1.65 eV with a maximum absorption peak at 558 nm. TP indicates good complementary absorption with visible light, absorbing most typically used fullerene-based acceptors (PC70BM, intense absorption range: 300-450 nm with Eg of 1.80 eV) and non-fullerene acceptors (NFAs) namely ITIC (intense absorption range: 500–800 nm with Eg of 1.59 eV). In addition, TP exhibits good complementary absorption with NIR-absorbing NFAs namely IEICO-4F (intense absorption range: 600–1000 nm with Eg of 1.24 eV). The determined energy levels (-5.31 eV and -3.66 eV) of TP were found to be suitable as an electron donor for both fullerene and NFA OSCs. The TP:PC70BM blend provided a maximum power conversion efficiency (PCE) of 6.51% with an open-circuit voltage (Voc) of 0.79 V, short-circuit current (Jsc) of 13.50 mA/cm2, and fill factor (FF) of 0.61. The PCE was remarkably improved to 8.18% (Voc  0.89 V, Jsc  15.31 mA/cm2, and FF  0.60) and 8.73% (Voc  0.74 V, Jsc  21.44 mA/cm2, and FF  0.55), for the OSC device prepared using TP and NFAs such as ITIC and IEICO-4F. Surprisingly, the OSC device created using a ternary blend, TP:ITIC:IEICO-4F, provided an outstanding PCE of 9.80% (Voc  0.87 V, Jsc  19.09 mA/cm2, and FF  0.59). Keywords: polymer solar cells; binary organic solar cells; ternary organic solar cells; ternary polymers; random polymers 2 ACS Paragon Plus Environment

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Introduction Solar cells (SCs) are considered as the most promising green electrical energy production option owing to their abundant energy resource and environment friendly energy production methods.1–5 Currently, several types of solar cells such as silicon-based solar cells (Si SCs),6–8 cadmium telluride solar cells (CdTe SCs),9– 11 copper

indium gallium selenide solar cells (CIGS SCs),12–14 perovskite solar cells

(Per SCs),15–18 dye-sensitized solar cells (DSSCs),19–22 and organic solar cells (OSCs)23–30 are under effective investigation. All are classified under inorganicbased

solar

cells

except

DSSCs

and

OSCs

because

inorganic-based

semiconducting materials are used for light harvesting and charge separation. Regarding DSSCs, both organic19–21 and inorganic20,21 sensitizers have been utilized for energy conversion, whereas organic semiconducting materials, such as π–conjugated polymers and organic small-molecule-based electron-donor and acceptor materials,23–30 have been used to harvest light as well as for charge separation on OSCs. The power conversion efficiency (PCE) of the inorganicbased solar cells are higher than that of OSCs; however, OSCs are still garnering particular attention owing to their advantages such as flexibility and facile device fabrication at low cost, solution processability, and low-temperature process.1–5,23– 30

Over the last decade, the overall performance has improved gradually over 14%

for single junction OSCs31–36 and up to 17% for multijunction or tandem OSCs37 through using the appropriate donor and acceptor materials on their photoactive layer,23–37 photoactive layer surface morphology control,38–40 and interface and electrode engineering.41–45



Noticeably, the efficiency of the OSC device is highly reliant on the properties of the donor: acceptor blend used on its photoactive layer.23–37 Therefore, the development of new donor and acceptor materials is highly encouraged to further enhance the OSC performance. Over the last decade, π– conjugated organic polymers have generally been utilized as an electron donor and fullerene derivatives as an electron acceptor.27,30 Fullerene derivatives (example: PC60BM and PC70BM) exhibit intense absorption (300–450 nm) at the high-energy region of the solar spectra;28,46 consequently, low bandgap donor polymers have been preferred as an electron donor to maximize the photocurrent of the device via complementary absorption from the polymer and PC70BM. Reports of nonfullerene organic molecule acceptor (NFA)-based OSCs providing an improved short-circuit current (Jsc) and open-circuit voltage (Voc), and consequently a higher PCE compared to fullerene-based OSCs have been published recently.23–26,31–37 The efficient NFAs exhibited strong absorption (between 500–1000 nm) at the lowenergy region of the solar spectra; therefore, wide bandgap donor polymers are desired as an electron donor to achieve high photocurrents. However, low bandgap polymers are still useful because NIR-absorbing NFAs have also been applied to OSCs. For example, the maximum PCE of 14% was obtained for the OSCs prepared using wide bandgap polymers and low bandgap NFAs.31–36 Meanwhile, the OSCs fabricated using low bandgap polymers and ultrasmall bandgap NFAs provided a PCE of up to 13%.47–52 We intend to develop an efficient polymeric donor that is suitable with a wide range of acceptors, such as PC70BM (absorption range: 300–450 nm), ITIC


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(absorption range: 500–800 nm), and IEICO-4F (absorption range: 600–1000 nm), as shown by their absorptions at different intervals of the solar spectrum. It is noteworthy that the low bandgap (Eg  1.59 eV) polymer PTB7-Th ( P1, poly(4,8bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-bʹ]dithiophene-alt-2-ethylhexyl

3-

fluorothieno[3,4-b]thiophene-2-carboxylate) exhibited a high efficiency when blended with PC70BM and IEICO-4F.49,52 However, the performance was relatively poor when PTB7-Th was blended with ITIC owing primarily to its poor complementary absorption. Meanwhile, one of our recently reported wide bandgap (Eg  2.01 eV) polymer PBDTT-ttPPD ( P2, poly(4,8-bis(5-(2-ethylhexyl)thiophen2-yl)benzo[1,2-b:4,5-bʹ]dithiophene-alt-5-octyl-2-(2-octyldodecyl)-4,6-di(thieno[3,2b]thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione) exhibited good photovoltaic performance (PCE  6.9%, Voc  0.87 V, Jsc  11.38 mA/cm2, and FF  0.70) for OSCs fabricated with the P2:PC70BM blend.53 The NFA OSC device fabricated using the P2:ITIC blend was also found to provide a decent performance (PCE  7.63%), but the device fabricated using P2:IEICO-4F blend offered poor performance (PCE  1.89%). The poor performance could be primarily due to the poor complementary absorption of P2:IEICO-4F blend. The chemical structures and absorption spectra of P1, P2, ITIC, and IEICO-4F are shown in Figs. S1 and S2. The structural similarity of P1 and P2 indicates that the ternary polymer containing benzo[1,2-b:4,5-bʹ]dithiophene, pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione, and thieno[3,4-b]thiophene derivatives might be a potential candidate for both visible and NIR light-absorbing OSCs. In this instance, we synthesized a new ternary polymer, TP, and briefly studied their properties. 5 ACS Paragon Plus Environment


Results and discussions Synthesis, optical, and electrochemical properties The Stille polymerization of BDTT, PPD, and TT derivatives afforded the ternary polymer TP; the synthesis route of TP is outlined in Scheme 1. Good solubility was indicated for TP, and the weight average (Mw)/number average (Mn) molecular weights determined using chloroform were 4.30 × 104 g/mol / 2.23 × 104 g/mol with a polydispersity index (PDI = Mw/Mn) of 1.93. The molecular weights of TP were found to be high and sufficiently for an efficient charge transport.54-56 The absorption spectra of the polymers P1, P2, and TP are compared in Fig. 1a. As expected, TP displayed a redshift absorption band and a lower bandgap compared to that of P2. Meanwhile, TP exhibited a clear blue-shift absorption band with a higher bandgap compared to P1. Fig. 1b presents the absorption spectra of TP along with NFAs such as ITIC and IEICO-4F, and indicates that the new polymer, TP presents good complementary absorption with both ITIC and IEICO-4F. Further, cyclic voltammetry analysis for TP was performed to determine their highest occupied/lowest unoccupied molecular orbital (HOMO/LUMO) energy levels. The cyclic voltammogram for TP is shown in Fig. 1c. The calculated HOMO and LUMO levels of TP were -5.31 eV and -3.66 eV, respectively. Overall, TP exhibited suitable energy levels to utilize as an electron donor with different electron acceptors such as PC70BM (HOMO/LUMO  -5.93 eV/-3.91 eV),46 ITIC (HOMO/LUMO  -5.48 eV/-3.83 eV),57 and IEICO-4F (HOMO/LUMO  ‒5.44 eV/4.19 eV).52 In Table 1, the opto–electrical properties of the polymers P1–TP are compared to gain a better understanding.


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Scheme 1. Synthetic route for the synthesis of TP.

Fig. 1. (a) Comparison of absorption spectra of TP with P1 and P2, and (b) TP with PC70BM, ITIC and IEICO-4F as thin films, (c) Cyclic voltammogram for TP. Table 1. Properties of polymers P1, P2, and TP. Polymer

max, film (nm)c

Eg (eV)d

HOMO (eV)e

LUMO (eV)f

P1a

692

1.59

‒5.30

‒3.71

P2a

522

2.04

‒5.41

‒3.37

TP

558

1.65

‒5.31

‒3.66

a

Data for P1 are obtained from reference 58. b Data for P2 are obtained from reference 53. c Absorption maximum measured as thin film. d Band-gap calculated from the onset wavelength of absorption in thin film. e The HOMO level was determined from the cyclic voltammetry analysis. f The LUMO level was calculated by using the equation: LUMO = HOMO + Eg.



Photovoltaic properties of binary OSCs

Fig. 2. (a and b) Configuration of fullerene and NFA OSC devices and its energy-level diagram, (c and d) J–V and IPCE curves of OSC prepared using 1:1 (w/w) TP:PC70BM + 3 vol% DIO blend, 1:1.2 (w/w) TP:ITIC + 0.5 vol% DIO, and 1:1.2 (w/w) TP:IEICO-4F + 0.5 vol% DIO blends. Fig. 2. shows the OSC device structure (a), energy-level diagram of the device (b), current–voltage (J–V) curves of the OSCs (c), and incident photon to current efficiency (IPCE) spectra of the OSCs (d). Under the optimized conditions, TP-based fullerene OSCs provided a maximum PCE of 6.51% with a Voc of 0.79 V, Jsc of 13.50 mA/cm2, and FF of 0.61. Notably, the overall performance of TP is comparable with that of the devices prepared under similar conditions using P1 (PCE  8.08%, Voc  0.79 V, Jsc  15.45 mA/cm2, and FF  0.66)59 and P2 (PCE  6.93%, Voc  0.87 V, Jsc  11.38 8 ACS Paragon Plus Environment

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mA/cm2, and FF  0.70)53 The variation in the PCEs of P1, P2, and TP primarily originated from their difference in the Jsc and Voc. Jsc is primarily correlated with the absorption of polymer, and the order of Jsc (P1 > TP > P2) obtained from J–V measurements is found to be consistent with the order of the red-shifted absorption bands (P1 > TP > P2) of the polymers (see Fig. 1a). Meanwhile, Voc is generally correlated with the energy difference (∆E) between the HOMO and LUMO levels of the polymer and PC70BM, respectively. The calculated ∆E of TP is almost similar to that of P1 but significantly lower compared to that of P2; therefore, TP resulted in a slightly lower Voc than P2 but similar to P1.60,61 As shown in Fig. 1b, TP demonstrated a good complementary absorption with both visible and NIR light-absorbing NFAs such as ITIC and IEICO-4F. Therefore, we fabricated NFA OSCs using TP:ITIC and TP: IEICO-4F blends. It is noteworthy that the device structure of fullerene and NFA OSCs are similar except for the electrontransporting layer (ETL, PNF-Br) inserted between the photoactive layer and Al. The device fabricated using TP:ITIC provided a maximum PCE of 8.18% (Voc  0.89 V, Jsc  15.31 mA/cm2, and FF  0.60). Notably, TP:ITIC blend offered relatively higher Jsc and Voc, owing to the extended light absorption and higher ∆E, compared to that of the device prepared using TP:PC70BM blend, and increases (< 25%) the overall PCE by over 8%. Meanwhile, the PCE of the NFA OSC was further increased to 8.73% (Voc  0.74 V, Jsc  21.44 mA/cm2, and FF  0.55) by only replacing ITIC with NIR light-absorbing IEICO-4F. Notably, the Jsc was improved significantly but the Voc and FF reduced slightly compared to the TP:ITIC blend, thus limiting the overall PCE to below 9%. The photovoltaic performances of TP with different acceptors are summarized in Table 2. 9 ACS Paragon Plus Environment


Overall, TP provided a high efficiency for the OSCs fabricated with three different acceptors: PC70BM, ITIC, and IEICO-4F. To compare the photovoltaic performances and verify our ideology, we fabricated the NFA OSCs using P1 and P2 under the identical conditions with those of TP. The J–V curves and photovoltaic parameters of the NFA OSCs prepared using P1:ITIC, P1:IEICO-4F, P2:ITIC, and P2:IEICO-4F blends are shown in Fig. S3 and Table S1. TP indicated a significantly improved PCE compared to P1 when blended with ITIC. Meanwhile, TP indicated a significantly improved PCE compared to P2 when blended with IEICO-4F. As stated above, P1 and P2 exhibited good complementary absorption with IEICO-4F and ITIC, respectively, but TP indicated good complementary absorption with both IEICO-4F and ITIC. Therefore, TP exhibited a high PCE with both NFAs, but P1 and P2 indicated good PCE with IEICO-4F and ITIC, respectively. Those results indicate that our ideology is applicable and that the appropriate modification on the polymer backbone results in an efficient polymer for various acceptors.

Photovoltaic properties of ternary OSCs It is noteworthy that the TP:ITIC blend provides relatively higher Voc and FF compared to those of TP:IEICO-4F blend. In contrast, TP:IEICO-4F blend provides a significantly higher Jsc than TP:ITIC blend. In our opinion, the ternary OSCs fabricated using TP, ITIC, and IEICO-4F might offer optimal photovoltaic parameters for TP-based NFA OSCs. Consequently, we fabricated the NFA OSCs with TP:ITIC:IEICO-4F (at different ratio) blends. The J–V and IPCE curves of the ternary OSCs are shown in Fig. 3, and the photovoltaic parameters of the ternary OSCs are presented in Table 2. Surprisingly, the


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inclusion of IEICO-4F on TP:ITIC blend did not affect the Voc and FF significantly, but notably increased Jsc and PCE for the resulting ternary OSCs compared to TP:ITIC blend. However, the Voc and FF started to decrease along with the continuous increase in Jsc when the ratio of 1:0.7:0.5 (w/w/w) was used for TP:ITIC:IEICO-4F. The best results were obtained for the ternary OSCs fabricated using 1:0.8:0.4 (w/w/w) for TP:ITIC:IEICO-4F + 0.5 vol% DIO blend that resulted in the highest PCE of 9.80% (Voc  0.87 V, Jsc  19.09 mA/cm2, and FF  0.59). Overall, Jsc is a key parameter that affected the performances of TP-based OSCs significantly. Therefore, the Jscs of the OSCs fabricated with different TP:acceptor blends were verified with the calculated Jsc values obtained from the IPCE spectra shown in Figs. 2d and 3b. The Jsc from both J–V and IPCE correlated well with each other. The calculated Jscs from J–V and IPCE curves were 13.50, 15.31, 21.44, and 19.09 mA/cm2, and

12.54, 15.11, 20.19, and 18.52

mA/cm2, respectively, for the OSC devices made from TP:PC70BM, TP:ITIC, TP: IEICO-4F, and TP:ITIC:IEICO-4F blends. The error range was found to be within 5-10%. The recent report confirmed that the inclusion of NIR-light absorbing NFA (IEICO-4F) on the visible-light absorbing polymer:NFA (PBDB-T:HF-PCIC) blend notably improved the absorption and active layer morphology, and also significantly lower both radiative and non-radiative recombination.62 The resulting ternary OSC devices provided much improved Jsc with slightly lower Voc and FF compared to the binary OSC devices. We also observed a similar trend for TP-based binary and ternary OSCs. 62 Therefore, the improved Jsc of TP-based ternary OSCs is also expected from the combined effects such as improved absorption and morphology, and suppressed recombination on ternary blend compared to that of binary blend. On the other hand, the



Voc is slightly decreased for the ternary OSCs compared to the binary OSC made by using TP:ITIC blend. The theoretical Voc is the energy difference between the HOMO and LUMO of polymer and NFA (ITIC and IEICO-4F), and the LUMO of IEICO-4F (–4.19 eV) is relatively deeper than that of the LUMO of ITIC (–3.83 eV). Therefore, the inclusion of IEICO-4F on TP:ITIC blend slightly lowered the Voc. The FF of the ternary devices is also slightly dropped might be because of the difference in the charge transporting ability on binary and ternary systems. It is worth to notice that the similar trend is observed generally for ternary OSCs.62,63

Fig. 3. (a) J–V curve of ternary OSCs prepared using different ratios of TP:ITIC:IEICO4F + 0.5 vol% DIO blends. (b) IPCE spectra of ternary OSC device fabricated using 1:0.8:0.4 (w/w/w) TP:ITIC:IEICO-4F + 0.5 vol% DIO blend.


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Table 2. Photovoltaic parameters of OSCs. Blend Additive

Jsc (mA/cm2)a

Voc (V)b

FF c

PCEmax (%)d

PCEavg (%)e

1:1 (w/w) TP:PC70BM

3 vol% DIO

13.50

0.79

0.61

6.51

6.32

1:1.2 (w/w) TP:ITIC

0.5 vol% DIO

15.31

0.89

0.60

8.18

8.01

1:1.2 (w/w) TP:IEICO4F

0.5 vol% DIO

21.44

0.74

0.55

8.73

8.58

1:1.1:0.1 (w/w/w) TP:ITIC:IEICO-4F

0.5 vol% DIO

16.69

0.89

0.58

8.62

8.49


0.5 vol% DIO

17.04

0.89

0.59

8.95

8.80


0.5 vol% DIO

18.00

0.87

0.58

9.10

8.91


0.5 vol% DIO

19.09

0.87

0.59

9.80

9.71


0.5 vol% DIO

20.11

0.85

0.49

8.38

8.09

a

Open-circuit voltage.

b

Short-circuit current density.

c

Fill factor.

d

Maximum power

conversion efficiency. e Average power conversion efficiencies for ten devices. Surface morphology of the active layers of OSCs TEM and AFM images were measured for the active layers of fullerene and NFA OSCs to ensure that the morphology is optimized for efficient charge transfer from the photoactive layer to their respective electrodes. As shown in Fig. 4, all four blends do not exhibit any cluster and the morphology is expected to be favorable for a good charge



transport. Notably, the morphology of TP:PC70BM is slightly different compared to that of the TP:NFA blend. Meanwhile, the morphology of the films fabricated from two different NFAs such as TP:ITIC, TP:IEICO-4F, and TP:ITIC:IEICO-4F are similar. The calculated root-mean-square (rms) roughness for the TP:PC70BM, TP:ITIC, TP:IEICO4F, and TP:ITIC:IEICO-4F films are 1.60 nm, 0.75 nm, 1.96 nm, and 0.98 nm, respectively. Both PC70BM and IEICO-4F demonstrated a slightly higher rms but ITIC indicated an extremely smooth surface when it was blended with TP.

Fig. 4. (a-d) TEM and (a*-d*) AFM images of the films fabricated using 1:1 (w/w) TP:PC70BM + 3 vol% DIO, 1:1.2 (w/w) TP:ITIC + 0.5 vol% DIO, 1:1.2 (w/w) TP:IEICO-4F + 0.5 vol% DIO, and 1:0.8:0.4 (w/w/w) TP:ITIC:IEICO-4F + 0.5 vol% DIO blends.

Charge transport properties To obtain an insight into the charge transport ability of TP, as the polymer is paramount in the carrier mobilities of the donor:acceptor blend, we examine the carrier mobility 14 ACS Paragon Plus Environment

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(hole and electron) of three different donor:acceptor blends, such as 1:1 (w/w) TP:PC70BM + 3 vol% DIO, 1:1.2 (w/w) TP:ITIC + 0.5 vol% DIO, and 1:1.2 (w/w) TP: IEICO-4F + 0.5 vol% DIO, using the space-charge-limited current (SCLC) method. The hole-

and

electron-only

devices

were

ITO/PEDOT:PSS/donor:acceptor/MoO3/Al

fabricated and

with

the

structures

of

ITO/ZnO/donor:acceptor/Al,

respectively. The J–V curves for the respective devices are shown in Fig. S4. The determined hole and electron mobilities were  1.59 × 10–4, 1.73 × 10–4, and 1.54 × 10–4 cm2V−1s−1, and  1.86 × 10–4, 1.79 × 10–4, and 1.23 × 10–4, cm2V−1s−1, respectively, for the devices made from TP:PC70BM, TP:ITIC, and TP:IEICO-4F blends. Generally, a mobility exceeding 10–4 cm2V−1s−1 is sufficient for an efficient charge transport. Both the hole and electron mobilities of the TP: PC70BM or ITIC or IEICO-4F blends are found to be in the order of 10–4 cm2V−1s−1. Therefore, good charge transport is expected for TPbased OSCs. However, the well balanced hole and electron mobilities was noted for TP:ITIC compared to TP:PC70BM and TP:IEICO-4F blends.

Conclusions We synthesized a new ternary polymer, TP that provided high efficiency in both visible and NIR light-absorbing OSCs. The Stille polymerization of BDTT, PPD, and TT units at a 2:1:1 ratio afforded TP. The determined maximum absorption, optical bandgap, and HOMO/LUMO levels of TP were 558 nm, 1.65 eV, and -5.31/-3.66 eV, respectively. The electron-donating TP exhibited good complementary absorption with electronaccepting visible light-absorbing PC70BM, low bandgap ITIC, and ultrasmall bandgap IEICO-4F. The maximum PCE achieved for the OSCs fabricated with TP:PC70BM blend



was 6.51% (Voc  0.79 V, Jsc  13.50 mA/cm2, and FF  0.61). Meanwhile, the PCEs were improved considerably by up to 8.18% (Voc  0.89 V, Jsc  15.31 mA/cm2, and FF  0.60) and 8.73% (Voc  0.74 V, Jsc  21.44 mA/cm2, and FF  0.55) by replacing PC70BM with ITIC and IEICO-4F, respectively. Finally, the ternary OSCs fabricated using a blend of TP:ITIC:IEICO-4F provided the maximum PCE of 9.80% (Voc  0.87 V, Jsc  19.09 mA/cm2, and FF  0.59). The absorption of the photoactive layers of TP-based OSCs extended to the longer wavelength region in the order of TP:PC70BM < TP:ITIC < TP:IEICO-4F, and the improved complementary absorption resulted in higher Jsc and PCE for the respective OSCs. Overall, the synthesized polymer offered high PCE in both visible and NIR absorbing OSCs. The results shown herein is expected to benefit the design of new polymers for OSCs.

Supporting Information: The details of materials and measurements, synthesis and characterization of polymer, and OSC device fabrication and characterization are presented in sup. Inform.

ACKNOWLEDGMENT This research was supported by the NRF Grant funded by the Korea Government (NRF-2016R1A2B4011474, 2018R1A2B6006815).

REFERENCES


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Page 17 of 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


1.

Zhang, K.; Chen, Z.; Armin, A.; Dong, S.; Xia, R.; Yip, H.-L.; Shoaee, S.; Huang, F.; Cao, Y., Efficient Large Area Organic Solar Cells Processed by Blade-Coating With Single-Component Green Solvent. Solar RRL 2018, 2 (1), 1700169.

2. Gu, X.; Zhou, Y.; Gu, K.; Kurosawa, T.; Guo, Y.; Li, Y.; Lin, H.; Schroeder, B. C.; Yan, H.; Molina-Lopez, F.; Tassone, C. J.; Wang, C.; Mannsfeld, S. C. B.; Yan, H.; Zhao, D.; Toney, M. F.; Bao, Z., Roll-to-Roll Printed Large-Area All-Polymer Solar Cells with 5% Efficiency Based on a Low Crystallinity Conjugated Polymer Blend. Advanced Energy Materials 2017, 7 (14), 1602742. 3. Carlé, J. E.; Helgesen, M.; Hagemann, O.; Hösel, M.; Heckler, I. M.; Bundgaard, E.; Gevorgyan, S. A.; Søndergaard, R. R.; Jørgensen, M.; García-Valverde, R.; ChaoukiAlmagro, S.; Villarejo, J. A.; Krebs, F. C., Overcoming the Scaling Lag for Polymer Solar Cells. Joule 2017, 1 (2), 274-289. 4. Krebs, F. C.; Jørgensen, M.; Norrman, K.; Hagemann, O.; Alstrup, J.; Nielsen, T. D.; Fyenbo, J.; Larsen, K.; Kristensen, J., A complete process for production of flexible large area polymer solar cells entirely using screen printing First public demonstration. Solar Energy Materials and Solar Cells 2009, 93 (4), 422-441. 5. Krebs, F. C., Fabrication and processing of polymer solar cells: A review of printing and coating techniques. Solar Energy Materials and Solar Cells 2009, 93 (4), 394412. 6. Gimpel, T.; Winter, S.; Boßmeyer, M.; Schade, W., Quantum efficiency of femtosecond-laser sulfur hyperdoped silicon solar cells after different annealing regimes. Solar Energy Materials and Solar Cells 2018, 180, 168-172.



7. Lee, Y.; Park, C.; Balaji, N.; Lee, Y.-J.; Dao, V. A., High-efficiency Silicon Solar Cells: A Review. Israel Journal of Chemistry 2015, 55 (10), 1050-1063. 8. Blakers, A.; Zin, N.; McIntosh, K. R.; Fong, K., High Efficiency Silicon Solar Cells. Energy Procedia 2013, 33, 1-10. 9. Wu, X., High-efficiency polycrystalline CdTe thin-film solar cells. Solar Energy 2004, 77 (6), 803-814. 10. Chu, T. L.; Chu, S. S., Recent progress in thin-film cadmium telluride solar cells. Progress in Photovoltaics: Research and Applications 1993, 1 (1), 31-42. 11. Wang, J.-J.; Ling, T.; Qiao, S.-Z.; Du, X.-W., Double Open-Circuit Voltage of ThreeDimensional ZnO/CdTe Solar Cells by a Balancing Depletion Layer. ACS Applied Materials & Interfaces 2014, 6 (16), 14718-14723. 12. Ramanujam, J.; Singh, U. P., Copper indium gallium selenide based solar cells – a review. Energy & Environmental Science 2017, 10 (6), 1306-1319. 13. Kim, K.-B.; Kim, M.; Lee, H.-C.; Park, S.-W.; Jeon, C.-W., Copper indium gallium selenide (CIGS) solar cell devices on steel substrates coated with thick SiO2-based insulating material. Materials Research Bulletin 2017, 85, 168-175. 14. Singh, M.; Jiu, J.; Sugahara, T.; Suganuma, K., Thin-Film Copper Indium Gallium Selenide Solar Cell Based on Low-Temperature All-Printing Process. ACS Applied Materials & Interfaces 2014, 6 (18), 16297-16303. 15. Liu, Y.; Shin, I.; Ma, Y.; Hwang, I.-W.; Jung, Y. K.; Jang, J. W.; Jeong, J. H.; Park, S. H.; Kim, K. H., Bulk Heterojunction-Assisted Grain Growth for Controllable and Highly Crystalline Perovskite Films. ACS Applied Materials & Interfaces 2018, 10 (37), 31366-31373.


Page 18 of 25

Page 19 of 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


16. Xue, Q.; Xia, R.; Brabec, C. J.; Yip, H.-L., Recent advances in semi-transparent polymer and perovskite solar cells for power generating window applications. Energy & Environmental Science 2018, 11 (7), 1688-1709. 17. Wang, F.; Cao, Y.; Chen, C.; Chen, Q.; Wu, X.; Li, X.; Qin, T.; Huang, W., Materials toward the Upscaling of Perovskite Solar Cells: Progress, Challenges, and Strategies. Advanced Functional Materials 0 (0), 1803753. 18. Rong, Y.; Hu, Y.; Mei, A.; Tan, H.; Saidaminov, M. I.; Seok, S. I.; McGehee, M. D.; Sargent, E. H.; Han, H., Challenges for commercializing perovskite solar cells. Science 2018, 361 (6408), 8235. 19. Selopal, G. S.; Wu, H.-P.; Lu, J.; Chang, Y.-C.; Wang, M.; Vomiero, A.; Concina, I.; Diau, E. W.-G., Metal-free organic dyes for TiO2 and ZnO dye-sensitized solar cells. Scientific Reports 2016, 6, 18756. 20. Lee, C.-P.; Lin, R. Y.-Y.; Lin, L.-Y.; Li, C.-T.; Chu, T.-C.; Sun, S.-S.; Lin, J. T.; Ho, K.-C., Recent progress in organic sensitizers for dye-sensitized solar cells. RSC Advances 2015, 5 (30), 23810-23825. 21. Mishra, A.; Fischer, M. K. R.; Bäuerle, P., Metal-Free Organic Dyes for DyeSensitized Solar Cells: From Structure: Property Relationships to Design Rules. Angewandte Chemie International Edition 2009, 48 (14), 2474-2499. 22. Nazeeruddin, M. K.; Baranoff, E.; Grätzel, M., Dye-sensitized solar cells: A brief overview. Solar Energy 2011, 85 (6), 1172-1178. 23. Zhang, G.; Zhao, J.; Chow, P. C. Y.; Jiang, K.; Zhang, J.; Zhu, Z.; Zhang, J.; Huang, F.; Yan, H., Nonfullerene Acceptor Molecules for Bulk Heterojunction Organic Solar Cells. Chemical Reviews 2018, 118 (7), 3447-3507.



24. Yan, C.; Barlow, S.; Wang, Z.; Yan, H.; Jen, A. K. Y.; Marder, S. R.; Zhan, X., Nonfullerene acceptors for organic solar cells. Nature Reviews Materials 2018, 3, 18003. 25. Collins, S. D.; Ran, N. A.; Heiber, M. C.; Nguyen, T.-Q., Small is Powerful: Recent Progress in Solution-Processed Small Molecule Solar Cells. Advanced Energy Materials 2017, 7 (10), 1602242. 26. Chen, W.; Zhang, Q., Recent progress in non-fullerene small molecule acceptors in organic solar cells (OSCs). Journal of Materials Chemistry C 2017, 5 (6), 1275-1302. 27. Cai, Y.; Huo, L.; Sun, Y., Recent Advances in Wide-Bandgap Photovoltaic Polymers. Advanced Materials 2017, 29 (22), 1605437. 28. Cui, C.; Li, Y.; Li, Y., Fullerene Derivatives for the Applications as Acceptor and Cathode Buffer Layer Materials for Organic and Perovskite Solar Cells. Advanced Energy Materials 2017, 7 (10), 1601251. 29. An, Q.; Zhang, F.; Zhang, J.; Tang, W.; Deng, Z.; Hu, B., Versatile ternary organic solar cells: a critical review. Energy & Environmental Science 2016, 9 (2), 281-322. 30. Lu, L.; Zheng, T.; Wu, Q.; Schneider, A. M.; Zhao, D.; Yu, L., Recent Advances in Bulk Heterojunction Polymer Solar Cells. Chemical Reviews 2015, 115 (23), 1266612731. 31. Zheng, Z.; Hu, Q.; Zhang, S.; Zhang, D.; Wang, J.; Xie, S.; Wang, R.; Qin, Y.; Li, W.; Hong, L.; Liang, N.; Liu, F.; Zhang, Y.; Wei, Z.; Tang, Z.; Russell, T. P.; Hou, J.; Zhou, H., A Highly Efficient Non-Fullerene Organic Solar Cell with a Fill Factor over 0.80 Enabled by a Fine-Tuned Hole-Transporting Layer. Advanced Materials 2018, 30 (34), 1801801.


Page 20 of 25

Page 21 of 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


32. Zhang, H.; Yao, H.; Hou, J.; Zhu, J.; Zhang, J.; Li, W.; Yu, R.; Gao, B.; Zhang, S.; Hou, J., Over 14% Efficiency in Organic Solar Cells Enabled by Chlorinated Nonfullerene Small-Molecule Acceptors. Advanced Materials 2018, 30 (28), 1800613. 33. Li, S.; Ye, L.; Zhao, W.; Yan, H.; Yang, B.; Liu, D.; Li, W.; Ade, H.; Hou, J., A Wide Band Gap Polymer with a Deep Highest Occupied Molecular Orbital Level Enables 14.2% Efficiency in Polymer Solar Cells. Journal of the American Chemical Society 2018, 140 (23), 7159-7167. 34. Zhang, S.; Qin, Y.; Zhu, J.; Hou, J., Over 14% Efficiency in Polymer Solar Cells Enabled by a Chlorinated Polymer Donor. Advanced Materials 2018, 30 (20), 1800868. 35. Kan, B.; Feng, H.; Yao, H.; Chang, M.; Wan, X.; Li, C.; Hou, J.; Chen, Y., A chlorinated low-bandgap small-molecule acceptor for organic solar cells with 14.1% efficiency and low energy loss. Science China Chemistry 2018, 61 (10), 1307-1313. 36. Xiao, Z.; Jia, X.; Ding, L., Ternary organic solar cells offer 14% power conversion efficiency. Science Bulletin 2017, 62 (23), 1562-1564. 37. Meng, L.; Zhang, Y.; Wan, X.; Li, C.; Zhang, X.; Wang, Y.; Ke, X.; Xiao, Z.; Ding, L.; Xia, R.; Yip, H.-L.; Cao, Y.; Chen, Y., Organic and solution-processed tandem solar cells with 17.3% efficiency. Science 2018, 2612. 38. Jiao, X.; Ye, L.; Ade, H., Quantitative Morphology–Performance Correlations in Organic Solar Cells: Insights from Soft X-Ray Scattering. Advanced Energy Materials 2017, 7 (18), 1700084.



39. Huang, Y.; Kramer, E. J.; Heeger, A. J.; Bazan, G. C., Bulk Heterojunction Solar Cells: Morphology and Performance Relationships. Chemical Reviews 2014, 114 (14), 7006-7043. 40. Yang, X.; Loos, J., Toward High-Performance Polymer Solar Cells: The Importance of Morphology Control. Macromolecules 2007, 40 (5), 1353-1362. 41. Huai, Z.; Wang, L.; Sun, Y.; Fan, R.; Huang, S.; Zhao, X.; Li, X.; Fu, G.; Yang, S., High-Efficiency and Stable Organic Solar Cells Enabled by Dual Cathode Buffer Layers. ACS Applied Materials & Interfaces 2018, 10 (6), 5682-5692. 42. Sun, C.; Wu, Z.; Hu, Z.; Xiao, J.; Zhao, W.; Li, H.-W.; Li, Q.-Y.; Tsang, S.-W.; Xu, Y.-X.; Zhang, K.; Yip, H.-L.; Hou, J.; Huang, F.; Cao, Y., Interface design for highefficiency non-fullerene polymer solar cells. Energy & Environmental Science 2017, 10 (8), 1784-1791. 43. Yin, Z.; Wei, J.; Zheng, Q., Interfacial Materials for Organic Solar Cells: Recent Advances and Perspectives. Advanced Science 2016, 3 (8), 1500362. 44. Steim, R.; Kogler, F. R.; Brabec, C. J., Interface materials for organic solar cells. Journal of Materials Chemistry 2010, 20 (13), 2499-2512. 45. Oseni, S. O.; Mola, G. T., Properties of functional layers in inverted thin film organic solar cells. Solar Energy Materials and Solar Cells 2017, 160, 241-256. 46. He, Y.; Li, Y., Fullerene derivative acceptors for high performance polymer solar cells. Physical Chemistry Chemical Physics 2011, 13 (6), 1970-1983. 47. Gao, H.-H.; Sun, Y.; Wan, X.; Ke, X.; Feng, H.; Kan, B.; Wang, Y.; Zhang, Y.; Li, C.; Chen, Y., A New Nonfullerene Acceptor with Near Infrared Absorption for High


Page 22 of 25

Page 23 of 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Performance Ternary-Blend Organic Solar Cells with Efficiency over 13%. Advanced Science 2018, 5 (6), 1800307. 48. Yao, Z.; Liao, X.; Gao, K.; Lin, F.; Xu, X.; Shi, X.; Zuo, L.; Liu, F.; Chen, Y.; Jen, A. K. Y., Dithienopicenocarbazole-Based Acceptors for Efficient Organic Solar Cells with Optoelectronic Response Over 1000 nm and an Extremely Low Energy Loss. Journal of the American Chemical Society 2018, 140 (6), 2054-2057. 49. Song, X.; Gasparini, N.; Ye, L.; Yao, H.; Hou, J.; Ade, H.; Baran, D., Controlling Blend Morphology for Ultrahigh Current Density in Nonfullerene Acceptor-Based Organic Solar Cells. ACS Energy Letters 2018, 3 (3), 669-676. 50. Wang, W.; Zhao, B.; Cong, Z.; Xie, Y.; Wu, H.; Liang, Q.; Liu, S.; Liu, F.; Gao, C.; Wu, H.; Cao, Y., Nonfullerene Polymer Solar Cells Based on a Main-Chain Twisted Low-Bandgap Acceptor with Power Conversion Efficiency of 13.2%. ACS Energy Letters 2018, 3 (7), 1499-1507. 51. Huang, C.; Liao, X.; Gao, K.; Zuo, L.; Lin, F.; Shi, X.; Li, C.-Z.; Liu, H.; Li, X.; Liu, F.; Chen, Y.; Chen, H.; Jen, A. K. Y., Highly Efficient Organic Solar Cells Based on S,N-Heteroacene Non-Fullerene Acceptors. Chemistry of Materials 2018, 30 (15), 5429-5434. 52. Yao, H.; Cui, Y.; Yu, R.; Gao, B.; Zhang, H.; Hou, J., Design, Synthesis, and Photovoltaic Characterization of a Small Molecular Acceptor with an Ultra-Narrow Band Gap. Angewandte Chemie International Edition 2017, 56 (11), 3045-3049. 53. Tamilavan, V.; Lee, J.; Agneeswari, R.; Lee, D. Y.; Jung, Y. K.; Cho, S.; Jeong, J. H.; Jin, Y.; Hyun, M. H.; Park, S. H., Efficient pyrrolo[3,4-c]pyrrole-1,3-dione-based



wide band gap polymer for high-efficiency binary and ternary solar cells. Polymer 2017, 125, 182-189. 54. Wadsworth, A.; Hamid, Z.; Bidwell, M.; Ashraf, R. S.; Khan, J. I.; Anjum, D. H.; Cendra, C., Yan, J.; Rezasoltani, E.; Guilbert, A. A. Y.; Azzouzi, M.; Gasparini, N.; Bannock, J. H.; Baran, D.; Wu, H.; de Mello, J. C.; Brabec, C. J.; Salleo, A.; Nelson, J.; Laquai, F.; McCulloch, I., Progress in Poly (3-Hexylthiophene) Organic Solar Cells and the Influence of Its Molecular Weight on Device Performance. Advanced Energy Materials 2018, 8 (28), 1801001. 55. Hoefler, S. F.; Rath, T.; Pastukhova, N.; Pavlica, E.; Scheunemann, D.; Wilken, S.; Kunert, B.; Resel, R,; Hobisch, M.; Xiao, S.; Bratina, G.; Trimmel, G., The effect of polymer molecular weight on the performance of PTB7-Th:O-IDTBR non-fullerene organic solar cells. Journal of Materials Chemistry C 2018, 6 (20), 9506–9516. 56. Li, Z.; Yang, D.; Zhang, T.; Zhang, J.; Zhao, X.; Yang, X., High-Performance Additive-/Post-Treatment-Free Nonfullerene Polymer Solar Cells via Tuning Molecular Weight of Conjugated Polymers. Small 2018, 14 (16), 1704491. 57. Lin, Y.; Wang, J.; Zhang, Z.-G.; Bai, H.; Li, Y.; Zhu, D.; Zhan, X., An Electron Acceptor Challenging Fullerenes for Efficient Polymer Solar Cells. Advanced Materials 2015, 27 (7), 1170-1174. 58. Jiang, T.; Yang, J.; Tao, Y.; Fan, C.; Xue, L.; Zhang, Z.; Li, H.; Li, Y.; Huang, W., Random terpolymer with a cost-effective monomer and comparable efficiency to PTB7-Th for bulk-heterojunction polymer solar cells. Polymer Chemistry 2016, 7 (4), 926-932.


Page 24 of 25

Page 25 of 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


59. Lee, J.; Tamilavan, V.; Rho, K. H.; Keum, S.; Park, K. H.; Han, D.; Jung, Y. K.; Yang, C.; Jin, Y.; Jang, J.-W.; Jeong, J. H.; Park, S. H., Overcoming Fill Factor Reduction in Ternary Polymer Solar Cells by Matching the Highest Occupied Molecular Orbital Energy Levels of Donor Polymers. Advanced Energy Materials 2018, 8 (9), 1702251. 60. Elumalai, N. K.; Uddin, A., Open circuit voltage of organic solar cells: an in-depth review. Energy & Environmental Science 2016, 9 (2), 391-410. 61. Heeger, A. J., 25th Anniversary Article: Bulk Heterojunction Solar Cells: Understanding the Mechanism of Operation. Advanced Materials 2014, 26 (1), 10-28. 62. Zhan, L.; Li, S.; Zhang, H.; Gao, F.; Lau, T.-K.; Lu, X.; Sun, D.; Wang, P.;g Shi, M., Li, C.-Z., Chen, H., A Near-Infrared Photoactive Morphology Modifier Leads to Significant Current Improvement and Energy Loss Mitigation for Ternary Organic Solar Cells. Advanced Science 2018, 5 (8), 1800755. 63. Liu, X.; Yan, Y.; Yao, Y.; Liang, Z., Ternary Blend Strategy for Achieving HighEfficiency Organic Solar Cells with Nonfullerene Acceptors Involved. Advanced Functional Materials 2018, 28 (29), 1802004.


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