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Fullerene-free Organic Solar Cells with Efficiency of 10.2% and Energy Loss of 0.59 eV based on a Thieno[3,4c]Pyrrole-4,6-Dione Containing Wide-Bandgap Polymer Donor Wisnu Tantyo Hadmojo, Febrian Tri Adhi Wibowo, Du Yeol Ryu, In Hwan Jung, and Sung-Yeon Jang ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b09757 • Publication Date (Web): 07 Sep 2017 Downloaded from http://pubs.acs.org on September 7, 2017

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ACS Applied Materials & Interfaces

Fullerene-free Organic Solar Cells with Efficiency of 10.2% and Energy Loss of 0.59 eV based on a Thieno[3,4-c]Pyrrole-4,6-Dione Containing WideBandgap Polymer Donor

Wisnu Tantyo Hadmojo,† Febrian Tri Adhi Wibowo,† Du Yeol Ryu,‡ In Hwan Jung, *† SungYeon Jang *†

†

Department of Chemistry, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul

02707, Republic of Korea. E-mail: [email protected] (I. H. J.) & [email protected] (S.-Y. J) ‡

Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro,

Seodaemun-gu, Seoul 03722, Republic of Korea.

KEYWORDS: Organic solar cells, Wide bandgap polymer, Fullerene-free solar cells, Complementary absorption, Low energy loss.

ABSTRACT: Although the combination of wide-bandgap polymer donors and narrowbandgap small molecule acceptors achieved state-of-the-art performance as bulkheterojunction (BHJ) active layers for organic solar cells, there have been only several of

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wide-bandgap polymers actually realized high-efficiency devices over >10%. Herein, we developed high-efficiency, low-energy-loss fullerene-free organic solar cells using a weakly crystalline wide-bandgap polymer donor, PBDTTPD-HT, and a nonfullerene small molecule acceptor, ITIC. The excessive intermolecular stacking of ITIC is efficiently suppressed by the miscibility with PBDTTPD-HT, which led to a well-balanced nanomorphology in the PBDTTPD-HT:ITIC BHJ active films. The favorable optical, electronic, and energetic properties of PBDTTPD-HT with respect to ITIC achieved panchromatic photon-to-current conversion with remarkably low energy loss (0.59 eV).

INTRODUCTION During the last two decades, the performance of organic photovoltaic (OPV) devices has continuously been improved by synthesizing new active materials (donor and acceptors) and understanding device physics. The researches on active materials have predominantly focused on the development of donor materials, while fullerene derivatives have monopolized the role of acceptors. The optical absorption broadening, energy level matching, nanomorphology manipulation, and charge transport balance have widely been studied to optimize the combination of donors with fullerene acceptors.1-8 Recently, nonfullerene organic acceptors containing rhodanine,9-12 malononitrile,13-15 and diimide16-23 derivatives have been replacing the fullerene derivatives on the basis of superior performance. In particular, narrow-bandgap small molecule acceptors have recently emerged as promising materials, using which the power conversion efficiency (PCE) of >11% has been achieved.2430

The performance of narrow-bandgap small molecule acceptors was optimized by combination with wide-bandgap polymer donors.28-30 These wide-bandgap polymers usually demonstrated moderate performance when combined with fullerene acceptors due to limited


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optical absorption. However, their performance was further improved by blending with narrow-bandgap small molecule acceptors affording panchromatic photon-to-current conversion. For example, Hou et al. achieved devices PCE of 11.2% using a wide-bandgap polymer, PBDB-T, with a narrow-bandgap small molecule acceptors, ITIC, which is a value superior to that of fullerene-based devices (7.5%).29 Li et al. introduced a trialkylsilyl substituted benzodithiophene (BDT) in the donor polymer system and realized a PCE of 11.4%.30 However, thus far, only several of reported wide-bandgap donor materials achieved the devices with over 10% by combination with narrow-bandgap small molecule acceptors. The design strategy of donor materials for nonfullerene small molecule acceptors to achieve high efficiency OPVs has been discussed in the recent literature.31 Intuitively, the complementary absorption characteristics between donors and acceptors are crucial to enhance exciton generation. In terms of bulk-heterojunction (BHJ) nanomorphology, the suppression of excessive crystallization of the small molecule acceptors is important because it often causes the oversized segregated domains.14, 32-36 Thus, exceedingly high crystalline character of donor polymers is not favorable because it can facilitate oversized segregation. This is somewhat different from the conventional fullerene acceptors based BHJ layers, where highly crystalline donors are beneficial for charge transport properties.7, 31 Another important criterion for the design of donor materials is their energy levels; they should be located to minimize device energy loss (Eloss = Eg - qVOC, where q is the elementary charge), while securing efficient charge separation. The lowest unoccupied molecular orbital (LUMO) of the donors should be sufficiently high compared to that of the acceptors to inject the electrons from donors. Since the nonfullerene acceptors also considerably contribute to optical absorption, the location of highest occupied molecular orbital (HOMO) level of the donor is also important. The lower HOMO level of donor renders high open circuit voltage (VOC), however it should be high enough to secure the separation of holes from the



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nonfullerene acceptor. Not only optimized LUMO levels separation but also optimized HOMO levels separation is important in terms of charge separation and energy loss. Herein, we developed high-efficiency, low-energy-loss fullerene-free OPVs using PBDTTPD-HT as a wide-bandgap polymer donor (Eg = 1.88 eV),37 to construct BHJ active layers with a nonfullerene small molecule acceptor, ITIC (refer to the structures in Scheme 1). We selected and synthesized PBDTTPD-HT because it has appropriate energy levels and complementary absorption to ITIC. Thieno[3,4-c]pyrrole-4,6-dione (TPD) is a good building block for wide-bandgap polymers because of its moderate electron withdrawing property. The relatively unstabilized quinoid structure of TPD is advantageous to form a low-lying HOMO level, which is beneficial in terms of VOC of devices. Furthermore, the small-size TPD is easy to synthesis and the solubility is readily attained by the incorporation of alkyl side chains. However, in previously reported OPV devices using PBDTTPD-HT with fullerene acceptors, the PCE was reached only ~7% due to limited light absorption.38-42 In particular, PBDTTPD-HT has relatively low crystallinity because the alkyl groups on thiophene moieties are headed toward the BDT cores, which can break the symmetrical arrangement of the alkyl side chains. In this study, we posited that PBDTTPD-HT can be a good wide-bandgap donor polymer for narrow-bandgap small molecule acceptors such as ITIC that are highly crystalline. The PBDTTPD-HT donor polymer showed favorable optical, electronic, energetic, and morphological properties for ITIC, achieving panchromatic photonto-current conversion. Notably, the PBDTTPD-HT:ITIC based OPVs achieved a high PCE of 10.2% and a low energy loss (Eloss) of 0.59 eV (i.e. VOC of 0.97 V) simultaneously. The counterpart PBDTTPD-HT:PC70BM based OPVs showed a PCE of 7.3% with an Eloss of 0.68 eV (i.e. VOC of 0.88 V).

RESULTS AND DISCUSSION


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The wide-bandgap donor polymer, PBDTTPD-HT, was synthesized following a procedure in the literature with slight modification.37, 43 PBDTTPD-HT was polymerized by Stille coupling between 1 and 2 using Pd2(dba)3/P(o-tolyl)3 catalyst. The weight average molecular weight (Mw) of PBDTTPD-HT, measured by gel permeation chromatography (GPC) using polystyrene as a standard, was found to be 350,000 g/mol (PDI = 2.7). 1H and 13

C NMR of the synthesized monomers were recorded in Supporting Information (SI). The

absorption spectra of PBDTTPD-HT and ITIC solutions and films, measured by ultravioletvisible-near infrared (UV-vis-NIR), are shown in Figure 1a. The absorption of PBDTTPDHT was nearly complementary to ITIC with the absorption maxima at 556 nm (in solution) and 552 nm (in film). The absorption maxima of ITIC was in accordance with reported results (677 nm in solution and 720 nm in film). The large red-shift of ITIC from solution to film indicated that ITIC forms strong intermolecular stacking in a film state.44 In contrast, PBDTTPD-HT showed nearly identical absorption spectra in both solution and film except marginal development of a shoulder peak at 602 nm, which implies there is no considerable intermolecular stacking in the film state. The optical bandgap of PBDTTPD-HT, determined by absorption onset, was 1.88 eV. The HOMO level of PBDTTPD-HT, determined by cyclic voltammetry (CV)45, were -5.36 eV, while that of ITIC was -5.58 eV. The LUMO levels of PBDTTPD-HT and ITIC, determined using their optical bandgap and HOMO levels. were 3.48 eV and -4.02 eV, respectively. The energy diagram of the materials in our devices is shown in Figure 1b. The LUMO energy and HOMO energy differences between PBDTTPDHT and ITIC were -0.54 eV and -0.22 eV, respectively, which indicates there is sufficient driving force for the separation of hole-electron pairs generated in both PBDTTPD-HT and ITIC.46-47 Photovoltaic properties of PBDTTPD-HT:ITIC devices were investigated and compared to the PBDTTPD-HT:PC70BM based counterpart devices. Inverted structure OPV devices with



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an architecture of indium tin oxide (ITO)/ZnO/BHJ active layer/MoO3/Ag were fabricated. Current density-voltage (J-V) characteristics and external quantum efficiency (EQE) spectra of the devices are shown in Figure 2 and the resulting photovoltaic parameters are summarized in Table 1. The PBDTTPD-HT:PC70BM devices prepared with optimized fabrication conditions exhibited a PCE of 7.3% with a VOC of 0.88 V, a JSC of 11.50 mA cm-2, and a FF of 0.72. On the other hand, the PBDTTPD-HT:ITIC devices showed a much higher PCE of 10.2%, with a VOC of 0.97 V, a JSC of 15.40 mA cm-2, and a FF of 0.68. The results of the PBDTTPD-HT:ITIC device in various film fabrication conditions are summarized in SI (Figure S5 and Figure S6). The VOC of the PBDTTPD-HT:ITIC device was ~0.1 eV higher that of the PBDTTPD-HT:PC70BM devices because of the high-lying LUMO level of ITIC. In particular, the VOC value of 0.97 V is one of the highest values among reported high efficiency OPVs (PCE > 10%).14, 29-30, 48-49 The Eloss of our devices was remarkably low to be 0.59 eV. The high PCE of 10.2% and a very low Eloss (i.e. high VOC) of 0.59 eV were simultaneously achieved in our PBDTTPD-HT:ITIC devices because the HOMO level of PBDTTPD-HT is not only deep but also efficient for charge separation. The PBDTTPD-HT:ITIC devices also showed substantially enhanced JSC compared to PBDTTPD-HT:PC70BM devices because of the high EQE values in a much broader range (300 − 800 nm, Figure 2b). The EQE spectra of the PBDTTPD-HT:ITIC devices at longer wavelengths (650 – 750 nm) confirmed that the excitons generated by ITIC domains were efficiently separated at PBDTTPD-HT:ITIC interfaces and the holes are effectively collected through PBDTTPD-HT domains. The panchromatic photon to current conversion with low Eloss in our devices revealed the promise of our TPD containing PBDTTPD-HT as the donor for nonfullerene acceptors. Considering that there are limited numbers of polymer donors that have provided a high PCE (>10%) by combination with narrow bandgap nonfullerene acceptors, we posited that there


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are particular factors underlying the favorable properties of PBDTTPD-HT. We investigated the molecular ordering and nanomorphology of PBDTTPD-HT, ITIC, and PBDTTPDHT:ITIC BHJ films by two-dimensional grazing incidence X-ray diffraction (2D-GIXD). As shown in Figure 3, PBDTTPD-HT and ITIC pristine films showed π-π stacking in the faceon mode; a (010) diffraction peak along the Qz axis of 1.622 and 1.757 Å–1, respectively, which correspond to d-spacing of 3.87 and 3.57 Å, respectively (Figures 3a and 3b). In PBDTTPD-HT:ITIC BHJ films, the molecular ordering of ITIC was considerably reduced, while the π-π stacking distance among ITIC was increased from 3.57 Å to 3.69 Å (Figures 3e and 3f). The π-π stacking among PBDTTPD-HT was also weakened, while its distance remained unchanged (Figures 3e and 3f). This result revealed that the crystallization (or ordering) of ITIC can be significantly suppressed by blending with PBDTTPD-HT, while there is a marginal effect on PBDTTPD-HT. In PBDTTPD-HT:PC70BM BHJ films, the ordering of PBDTTPD-HT was consistent with unchanged π-π stacking distance (Figure 3f), while the azimuthally uniform ordering of PC70BM was dominant as indicated in the 2DGIXD patterns (Figure 3d). The morphology of the PBDTTPD-HT:ITIC and PBDTTPD-HT:PC70BM blend films was also examined by atomic force microscopy (AFM) and transmission electron microscopy (TEM) analyses (Figure 4). In AFM topographic images, the PBDTTPD-HT:ITIC film showed a highly uniform and smooth surface with a root mean square roughness (RRMS) of 0.171 nm, whereas the PBDTTPD-HT:PC70BM film showed sizable phase separation with a RRMS of 1.75 nm. In TEM images, the PBDTTPD-HT:PC70BM films showed aggregated PC70BM domains, while the PBDTTPD-HT:ITIC film showed no noticeable phase segregation (Figures 4b and 4d). It is conceivable that the similar π conjugation backbone structures of PBDTTPD-HT and ITIC have better miscibility than the blends of PBDTTPDHT and PC70BM, resulting in smoother film morphology with suppression of oversized



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aggregation. The charge mobility in BHJ blend films was investigated by space-charge-limited current (SCLC) measurement. Hole- and electron-only devices were designed using the following configurations of ITO/PEDOT:PSS/donor:acceptor/MoOx/Ag (Figure S7) and ITO/ZnO/ donor:acceptor/ZnO/Al (Figure S8), respectively. The hole (µh) and electron mobility (µe) were calculated in a steady-state SCLC trap free regime. The µh and µe of the PBDTTPDHT:ITIC film were 7.5 × 10−4 and 1.2 × 10−4 cm2 V−1·s−1, respectively. Although the crystallinity of PBDTTPD-HT in the BHJ films was low, as indicated in the 2D-GIXD results (Figures 3c and 3d), sufficiently high µh values were achieved. In addition, µe of the PBDTTPD-HT:ITIC devices was also comparable with that of the PBDTTPD-HT:PC70BM devices.43 The charge mobility characteristics in the PBDTTPD-HT:ITIC BHJ films indicated that the PBDTTPD-HT and ITIC played beneficial roles with respect to each other in terms of nanomorphology. Their sufficient miscibility suppressed the excessive aggregation of ITIC, while sizable face-on orientation of both was maintained, leading to good hole and electron transport in the devices. The charge collection properties of PBDTTPD-HT:ITIC devices were investigated from the maximum photo-induced carrier generation rate per unit volume (Gmax) and the charge collection probability (PC) of the devices. Figure S9 shows the plot of photocurrent (Jph) vs. effective voltage (Veff), where Veff = V0 − Vapp, V0 is the voltage at Jph = 0, and Vapp is the applied voltage.50 The saturation photocurrent density (Jsat) at a high Veff is limited by the total number of absorbed photons.51 Under short circuit conditions, the PC, expressed as JSC/Jsat,52 was 93%, indicating excellent exciton dissociation and charge transport in the active layer. Overall, the well-balanced nanomorphology of PBDTTPD-HT:ITIC BHJ layers was reflected as good charge collection properties.


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CONCLUSION The BHJ OPVs based on a low crystalline wide-bandgap donor polymer, PBDTTPD-HT, and a narrow-bandgap nonfullerene small molecule acceptor, ITIC, achieved a PCE of 10.2%. The PBDTTPD-HT:ITIC active layers exhibited controlled nanomorphology, in which the excessive segregation of ITIC was successfully suppressed due to miscibility with PBDTTPD-HT, and the sizable face-on orientation of both PBDTTPD-HT:ITIC and ITIC was maintained. Efficient exciton separation and charge transport were thereby achieved in the PBDTTPD-HT:ITIC layers. While the complementary absorption and balanced nanomorphology achieved panchromatic photon to current conversion, the well-matched energy levels between PBDTTPD-HT and ITIC led to remarkably low energy loss of 0.59 eV. This study suggests that PBDTTPD-HT is a good donor candidate to further improve device performance via combination with other narrow-bandgap nonfullerene acceptors.

EXPERIMENTAL Polymerization: A mixture of monomer 1 (290 mg, 0.299 mmol) and monomer 2 (226 mg, 0.299 mmol), Pd2(dba)3 (9 mg, 9 mmol) and P(o-tolyl)3 (11 mg, 36 mmol) was dissolved in degassed toluene (6 ml). The mixture was refluxed for 24 hours, and then the resulted viscous solution was transferred to excess methanol. The purification was following the typical procedure in the literature53-54 to yield the final polymer (230 mg, 65%). GPC: Mw 350,000; PDI 2.7. Anal. Calcd for [C68H85NO2S7]n: C, 69.52; H, 7.46; N, 1.19; O, 2.72; S, 19.10, Found: C,69.5; H, 7.3; N, 1.2; S, 18.7. 2,6-bis(trimethyltin)-4,8-bis(5-ethylhexyl-2-thienyl)-benzo[1,2-b:4,5-b]dithiophene (1).

1

H

NMR (CDCl3, 400 MHz, ppm): δ 7.70 (t, J = 4.0 Hz, 2H), 7.33 (d, J = 4.0 Hz, 2H), 6.91 (s, 2H), 2.87 (br, 4H), 1.70 (br, 2H), 1.36 (m, 16H), 0.95 (m, 12H), 0.41 (s, 18H).



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1,3-bis(5-bromo-4-hexylthiophen-2-yl)-5-octyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione 1

(2).

H NMR (CDCl3, 400 MHz, ppm): δ 7.61 (s, 2H), 3.62 (t, J = 7.2 Hz, 2H), 2.56 (t, J = 7.6 Hz,

4H), 1.62 (m, 6H), 1.33 (m, 22H), 0.90 (m, 9H). 13C NMR (CDCl3, 100 MHz, ppm): δ 162.46, 143.74, 135.48, 131.87, 130.27, 128.32, 113.55, 38.70, 31.80, 31.59, 29.65, 29.54, 29.21, 28.94, 28.52, 27.00, 22.63, 14.11.

Supporting Information 1

H and

13

C NMR, PL spectra, SCLC mobility of hole-only and electron-only devices, and

photovoltaic properties at the various condition are provided in detail. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding author * I. H. Jung ([email protected]) * S.-Y. Jang ([email protected])

ACKNOWLEDGEMENT The authors gratefully acknowledge support from the New and Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resources from the Ministry of Trade, Industry and Energy, Republic of Korea (No. 20163030013960), the Technology Development Program to Solve Climate Changes of the National Research Foundation (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2016M1A2A2940912), the National Research Foundation

(NRF)

Grant

funded

by

the

Korean


Government

(MSIP,

No.

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2016R1A5A1012966, No. 2017R1A2B2009178, and No. 2017R1C1B2010694), and the Global Scholarship Program for Foreign Graduate Students at Kookmin University in Korea.

REFERENCES 1. Cheng, Y.-J.; Yang, S.-H.; Hsu, C.-S., Synthesis of Conjugated Polymers for Organic Solar Cell Applications. Chem. Rev. 2009, 109 (11), 5868-5923. 2. Lu, L.; Zheng, T.; Wu, Q.; Schneider, A. M.; Zhao, D.; Yu, L., Recent Advances in Bulk Heterojunction Polymer Solar Cells. Chem. Rev. 2015, 115 (23), 12666-12731. 3. Li, M.; Gao, K.; Wan, X.; Zhang, Q.; Kan, B.; Xia, R.; Liu, F.; Yang, X.; Feng, H.; Ni, W.; Wang, Y.; Peng, J.; Zhang, H.; Liang, Z.; Yip, H.-L.; Peng, X.; Cao, Y.; Chen, Y., Solutionprocessed Organic Tandem Solar Cells with Power Conversion Efficiencies >12%. Nat. Photonics 2017, 11 (2), 85-90. 4. Kan, B.; Zhang, Q.; Li, M.; Wan, X.; Ni, W.; Long, G.; Wang, Y.; Yang, X.; Feng, H.; Chen, Y.,

Solution-Processed

Organic

Solar

Cells

Based

on

Dialkylthiol-Substituted

Benzodithiophene Unit with Efficiency Near 10%. J. Am. Chem. Soc. 2014, 136 (44), 15529-15532. 5. Lee, J.; Sin, D. H.; Moon, B.; Shin, J.; Kim, H. G.; Kim, M.; Cho, K., Highly Crystalline Low-Bandgap Polymer Nanowires Towards High-Performance Thick-Film Organic Solar Cells Exceeding 10% Power Conversion Efficiency. Energy Environ. Sci. 2017, 10 (1), 247-257. 6. He, Z.; Xiao, B.; Liu, F.; Wu, H.; Yang, Y.; Xiao, S.; Wang, C.; Russell, T. P.; Cao, Y., Single-Junction Polymer Solar Cells With High Efficiency and Photovoltage. Nat. Photonics 2015, 9 (3), 174-179. 7. Liu, Y.; Zhao, J.; Li, Z.; Mu, C.; Ma, W.; Hu, H.; Jiang, K.; Lin, H.; Ade, H.; Yan, H., Aggregation and Morphology Control Enables Multiple Cases of High-Efficiency Polymer



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

Solar Cells. Nat. Commun. 2014, 5, 5293. 8. Kim, J. Y.; Kim, Y. U.; Kim, H. J.; Um, H. A.; Shin, J.; Cho, M. J.; Choi, D. H., Side-chain Engineering of Diketopyrrolopyrrole-based Copolymer using Alkyl Ester Group for Efficient Polymer Solar Cell. Macromol. Res. 2016, 24 (11), 980-985. 9. Holliday, S.; Ashraf, R. S.; Nielsen, C. B.; Kirkus, M.; Röhr, J. A.; Tan, C.-H.; ColladoFregoso, E.; Knall, A.-C.; Durrant, J. R.; Nelson, J.; McCulloch, I., A Rhodanine Flanked Nonfullerene Acceptor for Solution-Processed Organic Photovoltaics. J. Am. Chem. Soc. 2015, 137 (2), 898-904. 10. Wu, Y.; Bai, H.; Wang, Z.; Cheng, P.; Zhu, S.; Wang, Y.; Ma, W.; Zhan, X., A Planar Electron Acceptor for Efficient Polymer Solar Cells. Energy Environ. Sci. 2015, 8 (11), 3215-3221. 11. Holliday, S.; Ashraf, R. S.; Wadsworth, A.; Baran, D.; Yousaf, S. A.; Nielsen, C. B.; Tan, C.-H.; Dimitrov, S. D.; Shang, Z.; Gasparini, N.; Alamoudi, M.; Laquai, F.; Brabec, C. J.; Salleo, A.; Durrant, J. R.; McCulloch, I., High-Efficiency and Air-Stable P3HT-Based Polymer Solar Cells with a New Non-Fullerene Acceptor. Nat. Commun. 2016, 7, 11585. 12. Badgujar, S.; Song, C. E.; Oh, S.; Shin, W. S.; Moon, S.-J.; Lee, J.-C.; Jung, I. H.; Lee, S. K., Highly Efficient and Thermally Stable Fullerene-Free Organic Solar Cells Based on a Small Molecule Donor and Acceptor. J. Mater. Chem. A 2016, 4 (42), 16335-16340. 13. 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. Angew. Chem. Int. Ed. 2017, 56 (11), 3045-3049. 14. Lin, Y.; Zhao, F.; He, Q.; Huo, L.; Wu, Y.; Parker, T. C.; Ma, W.; Sun, Y.; Wang, C.; Zhu, D.; Heeger, A. J.; Marder, S. R.; Zhan, X., High-Performance Electron Acceptor with Thienyl Side Chains for Organic Photovoltaics. J. Am. Chem. Soc. 2016, 138 (14), 49554961.


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15. Zhang, G.; Yang, G.; Yan, H.; Kim, J.-H.; Ade, H.; Wu, W.; Xu, X.; Duan, Y.; Peng, Q., Efficient Nonfullerene Polymer Solar Cells Enabled by a Novel Wide Bandgap Small Molecular Acceptor. Adv. Mater. 2017, 29 (18), 1606054. 16. Hadmojo, W. T.; Nam, S. Y.; Shin, T. J.; Yoon, S. C.; Jang, S.-Y.; Jung, I. H., Geometrically Controlled Organic Small Molecule Acceptors for Efficient Fullerene-Free Organic Photovoltaic Devices. J. Mater. Chem. A 2016, 4 (31), 12308-12318. 17. Sun, D.; Meng, D.; Cai, Y.; Fan, B.; Li, Y.; Jiang, W.; Huo, L.; Sun, Y.; Wang, Z., NonFullerene-Acceptor-Based Bulk-Heterojunction Organic Solar Cells with Efficiency over 7%. J. Am. Chem. Soc. 2015, 137 (34), 11156-11162. 18. Zhao, D.; Wu, Q.; Cai, Z.; Zheng, T.; Chen, W.; Lu, J.; Yu, L., Electron Acceptors Based on α-Substituted Perylene Diimide (PDI) for Organic Solar Cells. Chem. Mater. 2016, 28 (4), 1139-1146. 19. Liu, T.; Meng, D.; Cai, Y.; Sun, X.; Li, Y.; Huo, L.; Liu, F.; Wang, Z.; Russell, T. P.; Sun, Y., High-Performance Non-Fullerene Organic Solar Cells Based on a SeleniumContaining Polymer Donor and a Twisted Perylene Bisimide Acceptor. Adv. Sci. 2016, 3 (9), 1600117. 20. Fernandez-Lazaro, F.; Zink-Lorre, N.; Sastre-Santos, A., Perylenediimides as NonFullerene Acceptors in Bulk-Heterojunction Solar Cells (BHJSCs). J. Mater. Chem. A 2016, 4 (24), 9336-9346. 21. Li, H.; Earmme, T.; Ren, G.; Saeki, A.; Yoshikawa, S.; Murari, N. M.; Subramaniyan, S.; Crane, M. J.; Seki, S.; Jenekhe, S. A., Beyond Fullerenes: Design of Nonfullerene Acceptors for Efficient Organic Photovoltaics. J. Am. Chem. Soc. 2014, 136 (41), 1458914597. 22. Hwang, Y.-J.; Li, H.; Courtright, B. A. E.; Subramaniyan, S.; Jenekhe, S. A., Nonfullerene Polymer Solar Cells with 8.5% Efficiency Enabled by a New Highly Twisted Electron



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

Acceptor Dimer. Adv. Mater. 2016, 28 (1), 124-131. 23. Hadmojo, W. T.; Yim, D.; Aqoma, H.; Ryu, D. Y.; Shin, T. J.; Kim, H. W.; Hwang, E.; Jang, W.-D.; Jung, I. H.; Jang, S.-Y., Artificial Light-Harvesting N-Type Porphyrin for Panchromatic Organic Photovoltaic Devices. Chem. Sci. 2017, 8 (7), 5095-5100. 24. Lin, Y.; Zhao, F.; Wu, Y.; Chen, K.; Xia, Y.; Li, G.; Prasad, S. K. K.; Zhu, J.; Huo, L.; Bin, H.; Zhang, Z.-G.; Guo, X.; Zhang, M.; Sun, Y.; Gao, F.; Wei, Z.; Ma, W.; Wang, C.; Hodgkiss, J.; Bo, Z.; Inganäs, O.; Li, Y.; Zhan, X., Mapping Polymer Donors toward High-Efficiency Fullerene Free Organic Solar Cells. Adv. Mater. 2017, 29 (3), 1604155. 25. Liang, N.; Jiang, W.; Hou, J.; Wang, Z., New Developments in Non-Fullerene Small Molecule Acceptors for Polymer Solar Cells. Mater. Chem. Front. 2017, 1 (7), 1291-1303. 26. Kuzmich, A.; Padula, D.; Ma, H.; Troisi, A., Trends in the Electronic and Geometric Structure of Non-Fullerene Based Acceptors for Organic Solar Cells. Energy Environ. Sci. 2017, 10 (2), 395-401. 27. Li, S.; Ye, L.; Zhao, W.; Zhang, S.; Mukherjee, S.; Ade, H.; Hou, J., Energy-Level Modulation of Small-Molecule Electron Acceptors to Achieve over 12% Efficiency in Polymer Solar Cells. Adv. Mater. 2016, 28 (42), 9423-9429. 28. Zhao, J.; Li, Y.; Yang, G.; Jiang, K.; Lin, H.; Ade, H.; Ma, W.; Yan, H., Efficient Organic Solar Cells Processed from Hydrocarbon Solvents. Nat. Energy 2016, 1, 15027. 29. Zhao, W.; Qian, D.; Zhang, S.; Li, S.; Inganäs, O.; Gao, F.; Hou, J., Fullerene-Free Polymer Solar Cells with over 11% Efficiency and Excellent Thermal Stability. Adv. Mater. 2016, 28 (23), 4734-4739. 30. Bin, H.; Gao, L.; Zhang, Z.-G.; Yang, Y.; Zhang, Y.; Zhang, C.; Chen, S.; Xue, L.; Yang, C.; Xiao, M.; Li, Y., 11.4% Efficiency Non-Fullerene Polymer Solar Cells with Trialkylsilyl Substituted 2D-Conjugated Polymer as Donor. Nat. Commun. 2016, 7, 13651. 31. Li, Z.; Jiang, K.; Yang, G.; Lai, J. Y. L.; Ma, T.; Zhao, J.; Ma, W.; Yan, H., Donor Polymer


Page 14 of 25

Page 15 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


Design Enables Efficient Non-Fullerene Organic Solar Cells. Nat. Commun. 2016, 7, 13094. 32. Bin, H.; Zhang, Z.-G.; Gao, L.; Chen, S.; Zhong, L.; Xue, L.; Yang, C.; Li, Y., NonFullerene Polymer Solar Cells Based on Alkylthio and Fluorine Substituted 2DConjugated Polymers Reach 9.5% Efficiency. J. Am. Chem. Soc. 2016, 138 (13), 46574664. 33. Baran, D.; Ashraf, R. S.; Hanifi, D. A.; Abdelsamie, M.; Gasparini, N.; Rohr, J. A.; Holliday, S.; Wadsworth, A.; Lockett, S.; Neophytou, M.; Emmott, C. J. M.; Nelson, J.; Brabec, C. J.; Amassian, A.; Salleo, A.; Kirchartz, T.; Durrant, J. R.; McCulloch, I., Reducing the Efficiency-Stability-Cost Gap of Organic Photovoltaics with Highly Efficient and Stable Small Molecule Acceptor Ternary Solar Cells. Nat. Mater. 2017, 16 (3), 363-369. 34. Dai, S.; Zhao, F.; Zhang, Q.; Lau, T.-K.; Li, T.; Liu, K.; Ling, Q.; Wang, C.; Lu, X.; You, W.; Zhan, X., Fused Nonacyclic Electron Acceptors for Efficient Polymer Solar Cells. J. Am. Chem. Soc. 2017, 139 (3), 1336-1343. 35. Lin, Y.; Zhang, Z.-G.; Bai, H.; Wang, J.; Yao, Y.; Li, Y.; Zhu, D.; Zhan, X., HighPerformance Fullerene-Free Polymer Solar Cells with 6.31% Efficiency. Energy Environ. Sci. 2015, 8 (2), 610-616. 36. Zhao, F.; Dai, S.; Wu, Y.; Zhang, Q.; Wang, J.; Jiang, L.; Ling, Q.; Wei, Z.; Ma, W.; You, W.; Wang, C.; Zhan, X., Single-Junction Binary-Blend Nonfullerene Polymer Solar Cells with 12.1% Efficiency. Adv. Mater. 2017, 29 (18), 1700144. 37. Lu, K.; Fang, J.; Yan, H.; Zhu, X.; Yi, Y.; Wei, Z., A Facile Strategy to Enhance Absorption Coefficient and Photovoltaic Performance of Two-Dimensional benzo[1,2b:4,5-b′]dithiophene and thieno[3,4-c]pyrrole-4,6-dione Polymers via Subtle Chemical Structure Variations. Org. Electron. 2013, 14 (10), 2652-2661.



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

38. Zou, Y.; Najari, A.; Berrouard, P.; Beaupré, S.; Réda Aïch, B.; Tao, Y.; Leclerc, M., A Thieno[3,4-c]pyrrole-4,6-dione-Based Copolymer for Efficient Solar Cells. J. Am. Chem. Soc. 2010, 132 (15), 5330-5331. 39. Yuan, J.; Zhai, Z.; Dong, H.; Li, J.; Jiang, Z.; Li, Y.; Ma, W., Efficient Polymer Solar Cells with a High Open Circuit Voltage of 1 Volt. Adv. Funct. Mater. 2013, 23 (7), 885892. 40. Warnan, J.; Cabanetos, C.; Labban, A. E.; Hansen, M. R.; Tassone, C.; Toney, M. F.; Beaujuge, P. M., Ordering Effects in Benzo[1,2-b:4,5-b′]difuran-thieno[3,4-c]pyrrole-4,6dione Polymers with >7% Solar Cell Efficiency. Adv. Mater. 2014, 26 (25), 4357-4362. 41. Warnan, J.; El Labban, A.; Cabanetos, C.; Hoke, E. T.; Shukla, P. K.; Risko, C.; Brédas, J.-L.; McGehee, M. D.; Beaujuge, P. M., Ring Substituents Mediate the Morphology of PBDTTPD-PCBM Bulk-Heterojunction Solar Cells. Chem. Mater. 2014, 26 (7), 22992306. 42. Amb, C. M.; Chen, S.; Graham, K. R.; Subbiah, J.; Small, C. E.; So, F.; Reynolds, J. R., Dithienogermole As a Fused Electron Donor in Bulk Heterojunction Solar Cells. J. Am. Chem. Soc. 2011, 133 (26), 10062-10065. 43. Zhang, Y.; Deng, D.; Lu, K.; Zhang, J.; Xia, B.; Zhao, Y.; Fang, J.; Wei, Z., Synergistic Effect of Polymer and Small Molecules for High-Performance Ternary Organic Solar Cells. Adv. Mater. 2015, 27 (6), 1071-1076. 44. 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. Adv. Mater. 2015, 27 (7), 11701174. 45. Marcus, R. A., On the Theory of Oxidation—Reduction Reactions Involving Electron Transfer. V. Comparison and Properties of Electrochemical and Chemical Rate Constans1. J. Phys. Chem. 1963, 67 (4), 853-857.


Page 16 of 25

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


46. Ha, Y.-H.; Lee, J. E.; Hwang, M.-C.; Kim, Y. J.; Lee, J.-H.; Park, C. E.; Kim, Y.-H., A New BDT-Based Conjugated Polymer with Donor-Donor Composition for Bulk Heterojunction Solar Cells. Macromol. Res. 2016, 24 (5), 457-462. 47. Clarke, T. M.; Durrant, J. R., Charge Photogeneration in Organic Solar Cells. Chem. Rev. 2010, 110 (11), 6736-6767. 48. Qin, Y.; Uddin, M. A.; Chen, Y.; Jang, B.; Zhao, K.; Zheng, Z.; Yu, R.; Shin, T. J.; Woo, H. Y.; Hou, J., Highly Efficient Fullerene-Free Polymer Solar Cells Fabricated with Polythiophene Derivative. Adv. Mater. 2016, 28 (42), 9416-9422. 49. Zheng, Z.; Awartani, O. M.; Gautam, B.; Liu, D.; Qin, Y.; Li, W.; Bataller, A.; Gundogdu, K.; Ade, H.; Hou, J., Efficient Charge Transfer and Fine-Tuned Energy Level Alignment in a THF-Processed Fullerene-Free Organic Solar Cell with 11.3% Efficiency. Adv. Mater. 2017, 29 (5), 1604241. 50. Cowan, S. R.; Roy, A.; Heeger, A. J., Recombination in Polymer-Fullerene Bulk Heterojunction Solar Cells. Phys. Rev. B 2010, 82 (24), 245207. 51. Mihailetchi, V. D.; Xie, H. X.; de Boer, B.; Koster, L. J. A.; Blom, P. W. M., Charge Transport and Photocurrent Generation in Poly(3-hexylthiophene): Methanofullerene Bulk-Heterojunction Solar Cells. Adv. Funct. Mater. 2006, 16 (5), 699-708. 52. Yi, Z.; Ni, W.; Zhang, Q.; Li, M.; Kan, B.; Wan, X.; Chen, Y., Effect of Thermal Annealing on Active Layer Morphology and Performance for Small Molecule Bulk Heterojunction Organic Solar Cells. J. Mater. Chem. C 2014, 2 (35), 7247-7255. 53. Eom, S. H.; Nam, S. Y.; Do, H. J.; Lee, J.; Jeon, S.; Shin, T. J.; Jung, I. H.; Yoon, S. C.; Lee, C., Dark current reduction strategies using edge-on aligned donor polymers for high detectivity and responsivity organic photodetectors. Polym. Chem. 2017, 8 (23), 36123621. 54. Choi, E. Y.; Eom, S. H.; Song, C. E.; Nam, S. Y.; Lee, J.; Woo, H. Y.; Jung, I. H.; Yoon, S.



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C.; Lee, C., Synthesis and characterization of a wide bandgap polymer based on a weak donor-weak acceptor structure for dual applications in organic solar cells and organic photodetectors. Org. Electron. 2017, 46, 173-182.


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Scheme 1. Polymerization of PBDTTPD-HT under Pd2(dba)3 and P(o-tolyl)3, and the structure of ITIC described in the box.



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Figure 1. (a) Absorption spectra and (b) cyclic voltammetry results of PBDTTPD-HT and ITIC. The solvent for solution spectra is chloroform. The inset figure is the energy diagram of active materials calculated from the absorption onsets and oxidation potentials.


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Figure 2. (a) The J-V characteristics and (b) EQE of PBDTTPD-HT:ITIC and PBDTTPDHT:PC70BM photovoltaic devices The inset shows the inverted-structure device architecture.



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Figure 3. 2D-GIXD images of pristine and blend films: (a) PBDTTPD-HT, (b) ITIC, (c) PBDTTPD-HT:ITIC (1.0:1.4 w/w), (d) PBDTTPD-HT:PC70BM (1.0:1.4 w/w), Out-of-plane line-cut in (e) full range and (f) π-π stacking range.


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Figure 4. AFM (a, c) and TEM (b, d) images of active layer with identical fabrication conditions with photovoltaic devices: (a, b) PBDTTPD-HT:ITIC (1.0:1.4 w/w) and (c, d) PBDTTPD-HT:PC70BM (1.0:1.4 w/w).



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Table 1. Summary of photovoltaic properties PCE (%) Active layer a)

VOC (V)

JSC (mA·cm-2)

FF

0.88

11.50

0.72

7.3

[0.88±0.01]

[11.06±0.58]

[0.70±0.03]

[6.72±0.39]

0.97

15.40

0.68

10.2

[0.96±0.01]

[15.07±0.35]

[0.67±0.01]

[9.8±0.21]

[average]b)

PBDTTPD-HT:PC70BM

PBDTTPD-HT:ITIC

a) 0.8 vol % DIO additive, and b) the 15 devices are used for the average.


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TOC


Fullerene-Free Organic Solar Cells with an ... - ACS Publications

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