Next Article in Journal
PEG/PPG-PDMS-Adamantane-Based Crosslinked Terpolymer Using the ROMP Technique to Prepare a Highly Permeable and CO2-Selective Polymer Membrane
Next Article in Special Issue
Economic Evaluation and Techno-Economic Sensitivity Analysis of a Mass Integrated Shrimp Biorefinery in North Colombia
Previous Article in Journal
Nonlinear Optical Pigments. Two-Photon Absorption in Crosslinked Conjugated Polymers and Prospects for Remote Nonlinear Optical Thermometry
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Polymers
Volume 12
Issue 8
10.3390/polym12081673
polymers-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Comparing Benzodithiophene Unit with Alkylthionaphthyl and Alkylthiobiphenyl Side-Chains in Constructing High-Performance Nonfullerene Solar Cells

by
Ruyi Xie
1,2,3,4,*,†,
Li Song
1,3,† and
Zhihui Zhao
4,*
1
School of Textiles and Clothing, Qingdao University, 308 Ningxia Road, Qingdao 266071, China
2
Key Laboratory Clean Dyeing and Finishing Technology Zhejiang, Shaoxing University, Shaoxing 312000, China
3
Collaborative Innovation Center for Eco-Textiles of Shandong Province, 308 Ningxia Road, Qingdao 266071, China
4
State Key Laboratory of Bio-Fibers and Eco-Textiles, Qingdao University, Qingdao 266071, China
*
Authors to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Polymers 2020, 12(8), 1673; https://doi.org/10.3390/polym12081673
Submission received: 1 July 2020 / Revised: 22 July 2020 / Accepted: 24 July 2020 / Published: 27 July 2020
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
Browse Figures
Versions Notes

Abstract

:
Using single-bonded and fused aromatic rings are two methods for extending the π-conjugation in the vertical direction of benzo [1,2-b:4,5-b′] dithiophene (BDT) unit. To investigate which method is more efficient in nonfullerene systems, two novel polymers based on alkylthionaphthyl and alkylthiobiphenyl substituted BDT named PBDTNS-FTAZ and PBDTBPS-FTAZ are designed and synthesized. Two polymers only exhibit small differences in structure, but huge differences in photovoltaic properties. They are studied by blended with 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)indanone)-5,5,11,11-tetrakis(4-hexylphenyl)dithieno [2,3-d’:2,3’-d’]-s-indaceno [1,2-b:5,6-b’] dithiophene (ITIC). The device based on PBDTNS-FTAZ:ITIC showed the best power conversion efficiency (PCE) of 9.63% with the Voc of 0.87 V, a Jsc of 18.06 mA/cm2 and a fill factor of 61.21%, while the PBDTBPS-FTAZ:ITIC only exhibit a maximum PCE of 7.79% with a Voc of 0.86 V, a Jsc of 16.24 mA/cm2 and a relatively low fill factor of 55.92%. Therefore, extending π-conjugation with alkylthionaphthyl is more effective against constructing nonfullerene solar cells.

1. Introduction

Polymer solar cells (PSCs) have attracted tremendous attention from researchers all over the world due to its flexibility, low cost, extensive sources and the possibility for large-scale production [1,2,3,4,5,6]. These features promise a bright commercial prospect. Nonfullerene polymer solar cells have been a research hotspot recently. The power conversion efficiency (PCE) of widely studied n-type semiconductor 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]-dithiophene (ITIC)-based polymer solar cells have made significant progress in last two years [7,8,9,10,11,12,13,14] because of the advantage of broader absorption in the visible-near infrared region and fine-tuned energy level compared with the traditional PSCs based on fullerene acceptors [15,16,17]. With the development of new polymer donor and modification of nonfullerene acceptor, the PCE of nonfullerene PSCs has reached 13%–18% [3,11,18,19,20,21,22,23,24,25,26,27,28]. Designing and synthesizing novel medium bandgap polymer donors that match well with nonfullerene acceptors are also of vital importance in realizing high-performance solar cells.
There are two strategies to optimize their structure and enhance their photovoltaic performances: backbone engineering and side-chain engineering [3,21]. For backbone engineering, donor-acceptor (D-A) alternating copolymerization has been a widely applied method. Among the variety of donor units, benzo[1,2-b:4,5-b’]dithiophene (BDT) has been a splendid electron-donating building block due to its favorable planarity and intense π-π interaction [29,30,31,32]. Till now, a large amount of studies has been reported and demonstrated high efficiency. The power conversion efficiency (PCE) of the PSCs with BDT building block has reached 13–18% for single-junction devices [8,18,33,34,35,36,37].
Because the size, distribution and type of side-chains can greatly impact the configuration and properties of the materials, a significant number of trials have been devoted to side-chain engineering to explore high-performance photovoltaic materials [38,39,40]. Hou and coworkers designed two-dimensional BDT (BDTT) by incorporating thiophene conjugated side-chains to the BDT backbone [41], which have superior photovoltaic performance than the alkoxy-substituted BDT (1D-BDT). With the success of BDTT, more 2D-BDT monomers with larger side-chain π-conjugated systems were designed to extend the vertical conjugated length and further enhance π-π stacking. Up to now, conjugated 2D side-chains including thieno [3,2-b]thiophene, thiophene, benzene, biphenyl and naphthalene have been studied by many researchers [42,43,44,45,46,47,48]. Besides, the conjugated 2D side-chains can be simply modified by introducing oxygen or sulfur atoms. Interestingly, the sulfur atom possesses some special properties in PSCs. Introducing a sulfur atom could make the absorption of material red-shifted and the HOMO level decline. As a result, polymers containing alkylthio side-chains usually exhibit larger Jsc and Voc [49,50,51,52,53]. As reported, the BDT monomer substituted with alkylthiobiphenyl (BDTBPS) and alkylthionaphthyl (BDTNS) could be promising electron-donating units for designing high-performance donor polymers. Previous reports show the difference between introducing single-bonded and fused aromatic rings into a BDT unit in the fullerene system [48]. Therefore, what are the differences between the single-bonded and fused aromatic rings on aBDT unit in the nonfullerene system? A comparison needs to be conducted.
The fluorinated 2-alkyl-benzo[d] [1,2,3] triazoles (FTAZ) and fluorinated benzothiadiazole (ffBT) are two electron-withdrawing units for constructing D-A copolymers with 2D BDT. The TAZ-based polymers showed a higher LUMO energy level than the BT counterparts. Besides, the fluorine atom could pull down both the HOMO and LUMO energy levels of the polymer while holding the bandgap constant, leading to higher Voc. These make FTAZ more suitable for constructing medium bandgap donor polymer matching with ITIC [53].
Herein, fluorinated 2-alkyl-benzo[d] [1,2,3]triazoles (FTAZ) was chosen as the acceptor building block. The photovoltaic properties of two novel polymers based on BDTNS (named PBDTNS-FTAZ) and BDTBPS (named PBDTBPS-FTAZ) in nonfullerene systems were detailed studied. The PBDTNS-FTAZ:ITIC exhibit higher PCE of 9.64% with a Voc of 0.87 V, a Jsc of 18.06 mA/cm2 and a fill factor of 61.21%, while PBDTBPS-FTAZ:ITIC only shows a maximum PCE of 7.78% with a Voc of 0.86 V, a Jsc of 16.24 mA/cm2 and a relatively low fill factor of 55.92%.

2. Experimental Section

2.1. Materials and Reagents

All starting materials and reagents were purchased from commercial sources and utilized without further purification. Benzo[1,2-b:4,5-b’]dithiophene-4,8-dione was purchased from Derthon Optoelectronic Materials Science Technology Co., Ltd., Shenzhen, China, FTAZ were purchased from Solarmer Materials Inc., Irwindale, CA, United States. The purity of all reagents was 99% in the experiment. Toluene was dried over Na/benzophenone and freshly distilled before use. The synthetic routes of polymers PBDTNS-FTAZ and PBDTBPS-FTAZ are shown in Scheme 1.

2.2. Synthesis of PBDTNS-FTAZ and PBDTBPS-FTAZ

The compounds BDTNSSn and BDTBPSSn were synthesized as previously reported.

2.3. Synthesis of Polymer PBDTNS-FTAZ

Compounds BDTNSSn (128.1 mg, 0.1 mmol), FTAZ-Br (64.5 mg, 0.1 mmol), Pd2(dba)3 (1.8 mg, 0.002 mmol) and P(o-tol)3 (3.6 mg, 0.012 mmol) were added into a flask. The flask was subjected to more than three successive cycles of vacuum followed by refilling with argon. Then, 4 mL of toluene was added. The reaction mixture was heated to 110 °C under argon atmosphere. Two hours later, the mixture was cooled to room temperature and polymer PBDTNS-FTAZ was precipitated by the addition of methanol, filtered and purified by Soxhlet extraction with methanol, chloroform and o-dichlorobenzene (o-DCB), respectively. The o-DCB solution was concentrated by evaporation and then precipitated into methanol. The deep purple solid was filtered to yield the desired polymer PBDTPS-FTAZ (118.1 mg, 82% yield). Mn: 46 kDa, PDI: 2.4.

2.4. Synthesis of Polymer PBDTBPS-FTAZ

Compounds of BDTBPSSn (133.3 mg, 0.1 mmol), M2 (64.5 mg, 0.1 mmol), Pd2(dba)3 (1.8 mg, 0.002 mmol) and P(o-tol)3 (3.6 mg, 0.012 mmol) were added into a flask. The synthetic procedure is the same as the above procedure of PBDTNS-FTAZ. The deep purple PBDTBPS-FTAZ solid was obtained (116.4 mg, 78% yield). Mn: 42 kDa, PDI: 2.2.

2.5. Device Characterization

The polymer solar cell was fabricated utilizing the conventional device structure of ITO/PEDOT:PSS/Polymer:ITIC/PFN/Al. The active area of solar cells was 0.1 cm2. The ITO coated glasses were cleaned in an ultrasonic machine with ITO detergent, deionized water, acetone and isopropanol sequentially for 20 min each step. The cleaned ITO substrates were treated with oxygen plasma for 6 min and then covered with PEDOT: PSS (Baytron PVP Al 4083) by spin coating. The thickness of PEDOT: PSS was about 35 nm. Then, the substrates were annealed at 160 °C for 20 min. Sequentially, the substrate was transferred to the glove box filled with N2 atmosphere. The o-DCB solutions of polymers and ITIC were initially heated at 120 °C for 30 min and then stirred at room temperature for 6 h. The solutions were heated at 140 °C half an hour before spin coating. The solutions were hot spin-coated at 140 °C to make the active layer and the substrate was heated at 70 °C. After that, the PFN solutions were spin-coated above the active layer at 2500 rpm for 10 s as the buffer layer. Finally, the samples were transferred to a vacant chamber and Al (100 nm) was deposited in a high vacuum degree (5 × 10−4 Pa) via a mask that constrains the active area of 0.1 cm2.
The current density–voltage (J–V) curves were measured by Keithley 2420 source meter under simulated AM 1.5 G irradiation (100 mW /cm2) using a Newport solar simulator. The light intensity was calibrated by a standard silicon solar cell. The external quantum efficiency (EQE) of the solar cells was tested using a certified Newport incident photon conversion efficiency (IPCE) measurement.
Atomic force microscopy (AFM) measurement was performed by an Agilent 5400 with tapping mode. Transmission electron microscopy (TEM) images were obtained from a Hitachi H-7650 transmission electron microscope at an accelerating voltage of 100 kV. The absorption spectra were measured using a Hitachi U-400 UV–vis–NIR scanning spectrophotometer.

3. Result and Discussion

3.1. Synthesis and Characterization

The synthetic routes of the polymer PBDTNS-FTAZ and PBDTBPS-FTAZ are shown in Scheme 1. The polymers were obtained by a stille coupling reaction. The detailed synthetic procedure is displayed in the Experimental section. The thermal property of the polymers was measured by thermogravimetric analysis (TGA) in nitrogen atmosphere at the heating rate of 10 °C/min. As shown in Figure S1, PBDTNS-FTAZ and PBDTBPS-FTAZ exhibited high thermal stability with an onset decomposition temperature (Td) with a 5% weight loss located at 310 °C.

3.2. Optical Properties

The normalized ultraviolet–visible (UV–vis) absorption spectra of PBDTNS-FTAZ and PBDTBPS-FTAZ in dilute o-DCB and as a film are shown in Figure 1. The two polymers show very similar absorption features in both solutions and films. The PBDTNS-FTAZ and PBDTBPS-FTAZ two exhibit shoulder peaks in thin films, which were located at 588 and 597 nm. This could be attributed to the aggregations of the polymer chains. [54] The absorption peak of PBDTNS-FTAZ and PBDTBPS-FTAZ located at 544 and 552 nm, respectively, which can be assigned to the intramolecular charge-transfer between BDT and the FTAZ unit. In the film state, both two polymers exhibit a slight red-shift compared to the absorption spectra in dilute o-DCB solution, which could ascribe to the aggregation in the solid-state. The optical bandgaps (Egopt) of PBDTNS-FTAZ and PBDTBPS-FTAZ are evaluated to be 1.98 and 1.95 according to the equation Egopt = 1240/λ, respectively. λ represents the absorption onset of the polymers PBDTNS-FTAZ and PBDTBPS-FTAZ.

3.3. Electrochemical Properties

The electrochemical properties of PBDTNS-FTAZ and PBDTBPS-FTAZ were characterized by utilizing the cyclic voltammetry (CV) method. The CV curves are shown in Figure 2. The onset oxidation potentials (Eox) of PBDTNS-FTAZ and PBDTBPS-FTAZ was 0.97 eV and 0.95 eV vs the saturated calomel electrode (SCE). The calculated HOMO energy levels of PBDTNS-FTAZ and PBDTBPS-FTAZ were calculated to be −5.37 eV and −5.35 eV, respectively. The corresponding LUMO energy levels were −3.39 eV and −3.40 eV calculated by the HOMO energy levels and optical bandgap of the two polymers.

3.4. Photovoltaic Properties

To investigate the photovoltaic properties of these two polymers, BHJ polymer solar cells were fabricated using the conventional device structure (ITO/PEDOT:PSS/active layer/PFN/Al). The polymers and ITIC were dissolved in o-DCB. The solutions were initially stirred at 130 °C for one hour and then stirred at room temperature overnight. Devices with different donor/acceptor (D/A) ratios (1:1, 1:1.5, 1:2) were fabricated to explore the best D/A ratio of the blend. Current density–voltage (J–V) characteristics of all devices were tested under AM 1.5G illumination. The J–V curves are shown in Figure 3 and the corresponding device parameters are summarized in Table 1. From Table 1, it can be concluded that both PBDTNS-FTAZ and PBDTBPS-FTAZ exhibited the best photovoltaic performance when the weight ratio between the polymer and ITIC were 1:1.5. The optimal PCEs (8.17%, 9.64%, 6.49%) of PBDTNS-FTAZ:ITIC were all higher than the PCEs of PBDTBPS-FTAZ:ITIC (7.08%, 7.79%, 7.07%). The PCEs of both polymers did not improve with post thermal annealing or processing additives. The device based on PBDTNS-FTAZ:ITIC showed the best PCE of 9.63% with the Voc of 0.87V, a Jsc of 18.06 mA/cm2 and a fill factor of 61.21%, while the PBDTBPS-FTAZ:ITIC only exhibit a maximum PCE of 7.79% with a Voc of 0.86V, a Jsc of 16.24 mA/cm2 and a relatively low fill factor of 55.92%. The Voc, Jsc and fill factor of PBDTNS-FTAZ:ITIC were promoted simultaneously compared to PBDTBPS-FTAZ:ITIC. In addition, device stability is another important parameter for solar cells. The storage tests were carried out to investigate the ambient stability of PBDTNS-FTAZ and PBDTBPS-FTAZ-based devices (Figure 4a,b). After storage for 192 h in air, the PBDTNS-FTAZ-based devices exhibited more excellent ambient stability than that of PBDTBPS-FTAZ-based devices.
To further investigate the reason higher Jsc of PBDTNS-FTAZ were obtained compared to PBDTBPS-FTAZ. The external quantum efficiency (EQE) was performed and the curves are displayed in Figure 4c. Both the PBDTNS-FTAZ/ITIC and PBDTBPS-FTAZ/ITIC devices showed broad photoresponse from 470 to 720 nm. The EQE response of the PBDTNS-FTAZ-based device were higher than those of PBDTBPS-FTAZ in the whole spectral range, which could partly account for the higher Jsc of the PBDTNS-FTAZ-based device. The optimal devices possess a high and flat EQE value of over 65%. The calculated current density of 15.98 mA/cm2 and 17.86 mA/cm2 were obtained by integrating the EQE spectrum with the standard AM 1.5G solar spectrum, which is consistent with the measured Jsc value with little error (<5%).
The relationship of the photocurrent (Jph) and the effective applied voltage (Veff) were studied to further analyze the charge recombination process in the devices based on PBDTNS-FTAZ and PBDTBPS-FTAZ. The Jph is defined by JL-JD, where JL and JD refer to the current density under AM 1.5G illumination and in the dark, respectively. V is the applied voltage; and V0 refers to the effective voltage where JL = JD [55,56,57,58,59]. As displayed in Figure 5, the Jph of PBDTBPS-FTAZ-based devices could not reach the saturation current (Jsat) even the applied voltage is over 3V, indicating the relatively severe charge recombination in the PBDTBPS-FTAZ:ITIC blend. On the contrary, the Jph of the PBDTNS-FTAZ-based devices reached the saturation value (Jsat) at a low applied voltage of 1 V, proving that the photogenerated excitons in PBDTNS-FTAZ-based devices were fully dissociated to free charges. The Jsat of the PBDTNS-FTAZ-based device was higher than the Jsat of PBDTBPS-FTAZ-based device, demonstrating that photogenerated current is larger in PBDTNS-FTAZ devices. The charge recombination and exciton dissociation in the PBDTNS-FTAZ:ITIC and PBDTBPS-FTAZ:ITIC device can be further investigated by the Jph/Jsat under short-circuit conditions. The Jsat of PBDTNS-FTAZ and PBDTBPS-FTAZ-based devices were 18.83 mA/cm2 and 17.17 mA/cm2, respectively. The Jph/Jsat of PBDTNS-FTAZ and PBDTBPS-FTAZ-based devices were 97.5% and 94.5%, respectively, proving that the PBDTNS-FTAZ-based device exhibited a better exciton dissociation efficiency at the D/A interfaces and then was collected at the electrodes with little recombination. As shown in Figure 6, the power-law dependence of photocurrent on light intensity (P), Jsc vs. Pα was plotted. The α value for PBDTNS-FTAZ:ITIC and PBDTBPS-FTAZ:ITIC was 0.985 and 0.938, respectively. The α value approaching one demonstrating there was little bimolecular recombination in PBDTNS-FTAZ:ITIC devices, which could account for the higher Jsc and FF of the PBDTNS-FTAZ-based devices [60,61,62,63].

3.5. Charge Transport Characteristics

The hole mobility of PBDTNS-FTAZ:ITIC and PBDTBPS-FTAZ:ITIC were characterized using the space-charge-limited-current (SCLC) method to study the charge transport ability. The J–V curves were shown in Figure S2. The hole only diodes were fabricated with the structure of ITO/PEDOT:PSS/active layer/Au. The hole mobility of PBDTNS-FTAZ and PBDTBPS-FTAZ are 6.64 × 10−5 cm2/Vs and 2.28 × 10−5 cm2/Vs, respectively. The PBDTNS-FTAZ exhibited higher hole mobility than PBDTBPS-FTAZ, which may result in a higher Jsc and FF in the PBDTNS-FTAZ-based devices.

3.6. Morphology Characterization

Transmission electron microscopy (TEM) and atomic force microscopy (AFM) measurements were performed to look into the surface morphology and the inside bulk structure of the active layer. As shown in Figure 7, the AFM and TEM images could tell that the PBDTNS-FTAZ:ITIC blend film possessed a smooth surface with a relatively low RMS of 1.17 and small aggregated microdomains. Indicating the PBDTNS-FTAZ polymer has excellent miscibility with ITIC. On the contrary, PBDTBPS-FTAZ:ITIC blend film exhibits a rough surface with a large RMS of 1.98 and a large scale of phase separation, indicating the aggregation of polymers and acceptors are severe in the blend film thus limiting the excitons separation and transportation. Thus, we can conclude that the compatibility of PBDTNS-FTAZ:ITIC is much better than that of PBDTBPS-FTAZ:ITIC, resulting in a much better morphology. A favorable morphology is vital for high-performance PSC, which could explain the higher Jsc and FF obtained in PBDTNS-FTAZ:ITIC device [64].

4. Conclusions

In summary, two novel 2D-BDT-based polymers containing alkylthionaphthyl (PBDTNS-FTAZ) and alkylthiobiphenyl (PBDTBPS-FTAZ) as side-chains were synthesized and photovoltaic properties in nonfullerene systems were compared in detail. The PBDTNS-FTAZ exhibited almost the same absorption property as PBDTBPS-FTAZ. However, the PBDTNS-FTAZ shows the better miscibility with ITIC compared with PBDTBPS-FTAZ. Therefore, the PBDTNS-FTAZ exhibited better EQE response, fill factor and yielded a higher PCE of 9.64%. This work proved that extending the side-chain on the BDT unit with fused aromatic rings providing better planarity could facilitate the stacking of polymer, avoiding excessive phase separation and improve PCE when blended with ITIC.

Supplementary Materials

The following are available online at https://www.mdpi.com/2073-4360/12/8/1673/s1. Figure S1: TGA plots of PBDTNS-FTAZ and PBDTBPS-FTAZ, Figure S2: J-V curves of vertical diodes with the device structures of ITO/PEDOT:PSS/polymer: ITIC/Au for hole only devices.

Author Contributions

Conceptualization, R.X.; data curation, R.X. and L.S.; formal analysis, R.X.; funding acquisition, R.X. and Z.Z.; investigation, R.X. and L.S.; methodology, R.X. and L.S.; project administration, Z.Z.; resources, R.X. and Z.Z.; software, R.X., L.S. and Z.Z.; supervision, R.X. and Z.Z.; validation, L.S. and Z.Z.; Visualization, R.X. and L.S.; writing—original draft, R.X.; writing—review and editing, R.X., L.S. and Z.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This work is supported by (1) Shandong Province Key Technology R&D Program, Grant No. 2017CXGC1006; (2) Opening Project of Key Laboratory of Clean Dyeing and Finishing Technology of Zhejiang Province, Project Number: QJRZ1908.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. 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 solar cells. Nat. Commun. 2014, 5, 5293. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  2. Chen, Y.; Ye, P.; Zhu, Z.G.; Wang, X.; Yang, L.; Xu, X.; Wu, X.; Dong, T.; Zhang, H.; Hou, J.; et al. Achieving high-performance ternary organic solar cells through tuning acceptor alloy. Adv. Mater. 2016, 29, 1603154. [Google Scholar] [CrossRef] [PubMed]
  3. Li, Y. Molecular design of photovoltaic materials for polymer solar cells: Toward suitable electronic energy levels and broad absorption. Acc. Chem. Res. 2012, 45, 723–733. [Google Scholar] [CrossRef] [PubMed]
  4. 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, 12666–12731. [Google Scholar] [CrossRef]
  5. Cheng, Y.J.; Yang, S.H.; Hsu, C.S. Synthesis of conjugated polymers for organic solar cell applications. Chem. Rev. 2009, 109, 5868–5923. [Google Scholar] [CrossRef]
  6. Tang, H.; Chen, H.; Yan, C.; Huang, J.; Fong, P.W.K.; Lv, J.; Hu, D.; Singh, R.; Kumar, M.; Xiao, Z.; et al. Delicate Morphology Control Triggers 14.7% Efficiency All-Small-Molecule Organic Solar Cells. Adv. Energy Mater. 2020. [Google Scholar] [CrossRef]
  7. Baran, D.; Ashraf, R.S.; Hanifi, D.A.; Abdelsamie, M.; Gasparini, N.; Röhr, J.A.; Holliday, S.; Wadsworth, A.; Lockett, S.; Neophytou, M.; et al. Reducing the efficiency–stability–cost gap of organic photovoltaics with highly efficient and stable small molecule acceptor ternary solar cells. Nat. Mater. 2017, 16, 363–369. [Google Scholar] [CrossRef]
  8. Qiao, S.; Li, X.; Wang, H.; Zhang, B.; Li, Z.; Zhao, J.; Chen, W.; Yang, R. Temperature-Dependent and Aggregation-Breaking Strategy for Benzodifuran-Constructed Organic Solar Cells. Sol. Rrl. 2019, 3, 1900159. [Google Scholar] [CrossRef]
  9. Dai, S.; Zhao, F.; Zhang, Q.; Lau, T.K.; Li, T.; Liu, K.; Ling, Q.; Wang, C.; Lu, X.; You, W.; et al. Fused nonacyclic electron acceptors for efficient polymer solar cells. J. Am. Chem. Soc. 2017, 139, 1336–1343. [Google Scholar] [CrossRef] [Green Version]
  10. Yang, Y.; Zhang, Z.G.; Bin, H.; Chen, S.; Gao, L.; Xue, L.; Yang, C.; Li, Y. Side-chain isomerization on an n-type organic semiconductor ITIC acceptor makes 11.77% high efficiency polymer solar cells. J. Am. Chem. Soc. 2016, 138, 15011–15018. [Google Scholar] [CrossRef]
  11. Bin, H.; Gao, L.; Zhang, Z.G.; Yang, Y.; Zhang, Y.; Zhang, C.; Chen, S.; Xue, L.; Yang, C.; Xiao, M.; et al. 11.4% Efficiency non-fullerene polymer solar cells with trialkylsilyl substituted 2D-conjugated polymer as donor. Nat. Mater. 2016, 7, 13651. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  12. Liu, D.; Yang, B.; Jang, B.; Xu, B.; Zhang, S.; He, C.; Woo, H.Y.; Hou, J. Molecular design of a wide-band-gap conjugated polymer for efficient fullerene-free polymer solar cells. Energy Environ. Sci. 2017, 10, 546–551. [Google Scholar] [CrossRef]
  13. Liu, Z.; Wang, N. Complementary light absorption and efficient exciton dissociation lead to efficient and excellent ternary polymer solar cells. J. Mater. Chem. A 2020, 8, 3211–3221. [Google Scholar] [CrossRef]
  14. Pan, M.A.; Lau, T.K.; Tang, Y.; Wu, Y.C.; Liu, T.; Li, K.; Chen, M.C.; Lu, X.; Ma, W.; Zhan, C. 16.7%-efficiency ternary blended organic photovoltaic cells with PCBM as the acceptor additive to increase the open-circuit voltage and phase purity. J. Mater. Chem. A 2019, 7, 20713–20722. [Google Scholar] [CrossRef]
  15. Guldi, D.M.; Illescas, B.M.; Ma, A.C.; Wielopolskia, M.; Martin, N. Fullerene for organic electronics. Chem. Soc. Rev. 2009, 38, 1587–1597. [Google Scholar] [CrossRef]
  16. He, Y.; Li, Y. Fullerene derivative acceptors for high performance polymer solar cells. Phys. Chem. Chem. Phys. 2011, 13, 1970–1983. [Google Scholar] [CrossRef]
  17. 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, 1170–1174. [Google Scholar] [CrossRef]
  18. Jiang, H.; Li, X.; Wang, H.; Huang, G.; Chen, W.; Zhang, R.; Yang, R. Appropriate Molecular Interaction Enabling Perfect Balance Between Induced Crystallinity and Phase Separation for Efficient Photovoltaic Blends. Acs Appl. Mater. Interfaces 2020, 12, 26286–26292. [Google Scholar] [CrossRef]
  19. Zhao, F.; Dai, S.; Wu, Y.; Zhang, Q.; Wang, J.; Jiang, L.; Ling, Q.; Wei, Z.; Ma, W.; You, W.; et al. Single-junction binary-blend nonfullerene polymer solar cells with 12.1% efficiency. Adv. Mater. 2017, 29, 1700144. [Google Scholar] [CrossRef] [Green Version]
  20. Li, X.; Huang, G.; Zheng, N.; Li, Y.; Kang, X.; Qiao, S.; Jiang, H.; Chen, W.; Yang, R. High-Efficiency Polymer Solar Cells Over 13.9% With a High VOC Beyond 1.0 V by Synergistic Effect of Fluorine and Sulfur. Sol. Rrl. 2019, 3, 1900005. [Google Scholar] [CrossRef]
  21. Zhang, Z.G.; Li, Y. Side-chain engineering of high-efficiency conjugated polymer photovoltaic materials. Sci. China Chem. 2015, 58, 192–209. [Google Scholar] [CrossRef]
  22. Ma, X.; An, Q.; Ibraikulov, O.A.; Lévêque, P.; Heiser, T.; Leclerc, N.; Zhang, X.; Zhang, F. Detecting bacteria and determining their susceptibility to antibiotics by stochastic confinement in nanoliter droplets using plug-based microfluidics. J. Mater. Chem. A 2020, 8, 1265–1272. [Google Scholar] [CrossRef]
  23. Yan, T.; Song, W.; Huang, J.; Peng, R.; Huang, L.; Ge, Z. 16.67% rigid and 14.06% flexible organic solar cells enabled by ternary heterojunction strategy. Adv. Mater. 2019, 31, 1902210. [Google Scholar] [CrossRef] [PubMed]
  24. Yan, T.; Ge, J.; Lei, T.; Zhang, W.; Song, W.; Fanady, B.; Zhang, D.; Chen, S.; Peng, R.; Ge, Z. 16.55% efficiency ternary organic solar cells enabled by incorporating a small molecular donor. J. Mater. Chem. A 2019, 7, 25894–25899. [Google Scholar] [CrossRef]
  25. Ma, Y.; Zhou, X.; Cai, D.; Tu, Q.; Ma, W.; Zheng, Q. A minimal benzo[c][1,2,5]thiadiazole-based electron acceptor as a third component material for ternary polymer solar cells with efficiencies exceeding 16.0%. Mater. Horiz. 2020, 7, 117–124. [Google Scholar] [CrossRef]
  26. Xu, X.; Feng, K.; Lee, Y.W.; Woo, H.Y.; Zhang, G.; Peng, Q. Subtle polymer donor and molecular acceptor design enable efficient polymer solar cells with a very small energy loss. Adv. Funct. Mater. 2020, 30, 1907570. [Google Scholar] [CrossRef]
  27. Zhan, L.; Li, S.; Lau, T.K.; Cui, Y.; Lu, X.; Shi, M.; Li, C.Z.; Li, H.; Hou, J.; Chen, H. Over 17% efficiency ternary organic solar cells enabled by two non-fullerene acceptors working in an alloy-like model. Energy Environ. Sci. 2020, 13, 635–645. [Google Scholar] [CrossRef]
  28. An, Q.; Wang, J.; Gao, W.; Ma, X.; Hu, Z.; Gao, J.; Xu, C.; Hao, M.; Zhang, X.; Yang, C.; et al. Alloy-like ternary polymer solar cells with over 17.2% efficiency. Sci. Bull. 2020, 65, 538–545. [Google Scholar] [CrossRef] [Green Version]
  29. Hou, J.; Park, M.H.; Zhang, S.; Yao, Y.; Chen, L.M.; Li, J.H.; Yang, Y. Bandgap and molecular energy level control. of conjugated polymer photovoltaic materials based on benzo[1,2-b:4,5-b’]dithiophene. Macromolecules 2008, 41, 6012–6018. [Google Scholar] [CrossRef] [Green Version]
  30. Liang, Y.; Xu, Z.; Xia, J.; Tsai, S.T.; Wu, Y.; Li, G.; Ray, C.; Yu, L. For the bright future-bulk heterojunction polymer solar cells with power conversion efficiency of 7.4%. Adv. Mater. 2010, 22, E135–E138. [Google Scholar] [CrossRef]
  31. Zhang, M.; Gu, Y.; Guo, X.; Liu, F.; Zhang, S.; Huo, L.; Russell, T.P.; Hou, J. Efficient polymer solar cells based on benzothiadiazole and alkylphenyl substituted benzodithiophene with a power conversion efficiency over 8%. Adv. Mater. 2013, 25, 4944–4949. [Google Scholar] [CrossRef] [PubMed]
  32. Zhang, M.; Guo, X.; Zhang, S.; Hou, J. Synergistic effect of fluorination on molecular energy level modulation in highly efficient photovoltaic polymers. Adv. Mater. 2014, 26, 1118–1123. [Google Scholar] [CrossRef] [PubMed]
  33. Song, J.; Li, C.; Zhu, L.; Guo, J.; Xu, J.; Zhang, X.; Weng, K.; Zhang, K.; Min, J.; Hao, X.; et al. Ternary organic solar cells with efficiency >16.5% based on two compatible nonfullerene acceptors. Adv. Mater. 2019, 31, 1905645. [Google Scholar] [CrossRef] [PubMed]
  34. Xie, G.; Zhang, Z.; Su, Z.; Zhang, X.; Zhang, J. 16.5% efficiency ternary organic photovoltaics with two polymer donors by optimizing molecular arrangement and phase separation. Nano Energy 2020, 69, 104447. [Google Scholar] [CrossRef]
  35. Chen, W.; Huang, G.; Li, X.; Li, Y.; Wang, H.; Jiang, H.; Zhao, Z.; Yu, D.; Wang, E.; Yang, R. Revealing the position effect of an alkylthio side chain in phenyl-substituted benzodithiophene-based donor polymers on the photovoltaic performance of non-fullerene organic solar cells. ACS Appl. Mater. Interfaces 2019, 11, 33173–33178. [Google Scholar] [CrossRef]
  36. Chen, W.; Huang, G.; Li, X.; Wang, H.; Li, Y.; Jiang, H.; Zheng, N.; Yang, R. Side-chain-promoted benzodithiophene-based conjugated polymers toward striking enhancement of photovoltaic properties for polymer solar cells. ACS Appl. Mater. Interfaces 2018, 10, 42747–42755. [Google Scholar] [CrossRef]
  37. Jiang, H.; Li, X.; Wang, H.; Ren, Z.; Zheng, N.; Wang, X.; Li, Y.; Chen, W.; Yang, R. Significantly enhanced molecular stacking in ternary bulk heterojunctions enabled by an appropriate side group on donor polymer. Adv. Sci. 2020, 7, 1903455. [Google Scholar] [CrossRef] [Green Version]
  38. Cabanetos, C.; El Labban, A.; Bartelt, J.A.; Douglas, J.D.; Mateker, W.R.; Frechet, J.M.J.; McGehee, M.D.; Beaujuge, P.M. Linear side chains in Benzo[1,2-b:4,5-b’]dithiophene-Thieno[3,4-c]pyrrole-4,6-dione polymers direct self-assembly and solar cell performance. J. Am. Chem. Soc. 2013, 135, 4656–4659. [Google Scholar] [CrossRef]
  39. Chen, M.S.; Lee, O.P.; Niskala, J.R.; Yiu, A.T.; Tassone, C.J.; Schmidt, K.; Beaujuge, P.M.; Onishi, S.S.; Toney, M.F.; Zettl, A.; et al. Enhanced solid-state order and field-effect hole mobility through control of nanoscale polymer aggregation. J. Am. Chem. Soc. 2013, 135, 19229–19236. [Google Scholar] [CrossRef]
  40. Cong, Z.; Zhao, B.; Wu, H.; Guo, Z.; Wang, W.; Luo, G.; Xu, J.; Xia, Y.; Gao, C.; An, Z. Synthesis of copolymers based on benzo[1,2-b:4,5-b ’]difuran and fluorinated quinoxaline derivatives and their photovoltaic properties. Polymer 2015, 67, 55–62. [Google Scholar] [CrossRef]
  41. Huo, L.; Zhang, S.; Guo, X.; Xu, F.; Li, Y.; Hou, J. Replacing alkoxy groups with alkylthienyl groups: A feasible approach to improve the properties of photovoltaic polymers. Angew. Chem. 2011, 123, 9871–9876. [Google Scholar] [CrossRef]
  42. Gong, X.; Li, G.; Li, C.; Zhang, J.; Bo, Z. Benzothiadiazole based conjugated polymers for high performance polymer solar cells. J. Mater. Chem. A 2015, 3, 20195–20200. [Google Scholar] [CrossRef]
  43. Kim, J.H.; Song, C.E.; Kim, B.; Kang, I.N.; Shin, W.S.; Hwang, D.H. Thieno[3,2-b]thiophene-Substituted benzo[1,2-b:4,5-b’]dithiophene as a promising building block for low bandgap semiconducting polymers for high-Performance single and tandem organic photovoltaic cells. Chem. Mater. 2014, 26, 1234–1242. [Google Scholar] [CrossRef]
  44. Xie, R.Y.; Fang, K.J.; Liu, Y.; Chen, W.C.; Fan, J.N.; Wang, X.W.; Ren, Y.F.; Song, Y.W. Z-scheme In2O3/WO3 heterogeneous photocatalysts with enhanced visible-light-driven photocatalytic activity toward degradation of organic dyes. J. Mater. Sci. 2020, 55, 11919–11937. [Google Scholar] [CrossRef]
  45. Wang, J.; Xiao, M.; Chen, W.; Qiu, M.; Du, Z.; Zhu, W.; Wen, S.; Wang, N.; Yang, R. Extending pi-conjugation system with benzene: An effective method to improve the properties of benzodithiophene-based polymer for highly efficient organic solar cells. Macromolecules 2014, 47, 7823–7830. [Google Scholar] [CrossRef]
  46. Li, X.; Huang, G.; Chen, W.; Jiang, H.; Qiao, S.; Yang, R. Size Effect of Two-Dimensional Conjugated Space in Photovoltaic Polymers’ Side Chain: Balancing Phase Separation and Charge Transport. ACS Appl. Mater. Interfaces 2020, 12, 16670–16678. [Google Scholar] [CrossRef]
  47. Yao, H.; Zhang, H.; Ye, L.; Zhao, W.; Zhang, S.; Hou, J. Molecular design and application of a photovoltaic polymer with improved optical properties and molecular energy levels. Macromolecules 2015, 48, 3493–3499. [Google Scholar] [CrossRef]
  48. Ding, D.; Wang, J.; Du, Z.; Li, F.; Chen, W.; Liu, F.; Li, H.; Sun, M.; Yang, R. A novel naphthyl side-chained benzodithiophene polymer for efficient photovoltaic cells with a high fill factor of 75%. J. Mater. Chem. A 2017, 5, 10430–10436. [Google Scholar] [CrossRef]
  49. Cui, C.; Wong, W.Y.; Li, Y. Improvement of open-circuit voltage and photovoltaic properties of 2D-conjugated polymers by alkylthio substitution. Energy Environ. Sci. 2014, 7, 2276–2284. [Google Scholar] [CrossRef]
  50. 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, 15529–15532. [Google Scholar] [CrossRef]
  51. Kan, B.; Zhang, Q.; Liu, F.; Wan, X.; Wang, Y.; Ni, W.; Yang, X.; Zhang, M.; Zhang, H.; Russell, T.P.; et al. Small molecules based on alkyl/alkylthio-thieno[3,2-b]thiophene-substituted benzo[1,2-b:4,5-b’]dithiophene for solution-processed solar cells with high performance. Chem. Mater. 2015, 27, 8414–8423. [Google Scholar] [CrossRef]
  52. Cui, C.; He, Z.; Wu, Y.; Cheng, X.; Wu, H.; Li, Y.; Cao, Y.; Wong, W.Y. A viscosity sensitive fluorescent dye for real-time monitoring of mitochondria transport in neurons. Energy Environ. Sci. 2016, 9, 885–891. [Google Scholar] [CrossRef]
  53. Kim, H.; Lim, B.; Heo, H.; Nam, G.; Lee, H.; Lee, J.Y.; Lee, J.; Lee, Y. High-efficiency organic photovoltaics with two-dimensional conjugated benzodithiophene-based regioregular polymers. Chem. Mater. 2017, 29, 4301–4310. [Google Scholar] [CrossRef]
  54. Wang, H.; Kong, H.; Zheng, J.; Peng, H.; Cao, C.; Qi, Y.; Fang, K.; Chen, W. Systematically Exploring Molecular Aggregation and Its Impact on Surface Tension and Viscosity in High Concentration Solutions. Molecules 2020, 25, 1588. [Google Scholar] [CrossRef] [Green Version]
  55. He, Z.; Zhong, C.; Huang, X.; Wong, W.Y.; Wu, H.; Chen, L.; Su, S.; Cao, Y. Simultaneous enhancement of open-circuit voltage, short-circuit current density, and fill factor in polymer solar cells. Adv. Mater. 2011, 23, 4636–4643. [Google Scholar] [CrossRef]
  56. Zhang, Q.; Kan, B.; Liu, F.; Long, G.; Wan, X.; Chen, X.; Zuo, Y.; Ni, W.; Zhang, H.; Li, M.; et al. Small-molecule solar cells with efficiency over 9%. Nat. Photonics 2015, 9, 35–41. [Google Scholar] [CrossRef]
  57. Chen, W.; Du, Z.; Xiao, M.; Zhang, J.; Yang, C.; Han, L.; Bao, X.; Yang, R. High-performance small molecule/polymer ternary organic solar cells based on a layer-by-layer process. ACS Appl. Mater. Interfaces 2015, 7, 23190–23196. [Google Scholar] [CrossRef]
  58. Chen, W.; Shen, W.; Wang, H.; Liu, F.; Duan, L.; Xu, X.; Zhu, D.; Qiu, M.; Wang, E.; Yang, R. Enhanced efficiency of polymer solar cells by improving molecular aggregation and broadening the absorption spectra. Dye. Pigm. 2019, 166, 42–48. [Google Scholar] [CrossRef]
  59. Jiang, H.; Li, X.; Wang, J.; Qiao, S.; Zhang, Y.; Zheng, N.; Chen, W.; Li, Y.; Yang, R. Ternary Polymer solar cells with high efficiency of 14.24% by integrating two well-complementary nonfullerene acceptors. Adv. Funct. Mater. 2019, 29, 1903596. [Google Scholar] [CrossRef]
  60. Lenes, M.; Morana, M.; Brabec, C.J.; Blom, P.W.M. Recombination-limited photocurrents in low bandgap polymer/fullerene solar cells. Adv. Funct. Mater. 2009, 19, 1106–1111. [Google Scholar] [CrossRef] [Green Version]
  61. Jiang, H.; Li, X.; Liang, Z.; Huang, G.; Chen, W.; Zheng, N.; Yang, R. Employing structurally similar acceptors as crystalline modulators to construct high efficiency ternary organic solar cells. J. Mater. Chem. A 2019, 7, 7760–7765. [Google Scholar] [CrossRef]
  62. Li, X.; Liang, Z.; Wang, H.; Qiao, S.; Liu, Z.; Jiang, H.; Chen, W.; Yang, R. Fluorinated D1((0.5))-A-D2((0.5))-A model terpolymer: Ultrafast charge separation kinetics and electron transfer at the fluorinated D/A interface for power conversion. J. Mater. Chem. A 2020, 8, 1360–1367. [Google Scholar] [CrossRef]
  63. Li, X.; Huang, G.; Jiang, H.; Qiao, S.; Kang, X.; Chen, W.; Yang, R. Novel benzodithiophene unit with an alkylthiobiphenyl side chain for constructing high-efficiency polymer solar cells. J. Mater. Chem. C 2019, 7, 6105–6111. [Google Scholar] [CrossRef]
  64. Wang, J.; Bao, X.; Ding, D.; Qiu, M.; Du, Z.; Wang, J.; Liu, J.; Sun, M.; Yang, R. A fluorine-induced high-performance narrow bandgap polymer based on thiadiazolo[3,4-c]pyridine for photovoltaic applications. J. Mater. Chem. A 2016, 4, 11729–11737. [Google Scholar] [CrossRef]
Polymers 12 01673 sch001 550
Scheme 1. Synthesis route of PBDTNS-FTAZ and PBDTBPS-FTAZ.
Scheme 1. Synthesis route of PBDTNS-FTAZ and PBDTBPS-FTAZ.
Polymers 12 01673 sch001
Polymers 12 01673 g001 550
Figure 1. Normalized absorption spectra of PBDTNS-FTAZ, PBDTBPS-FTAZ in o-DCB solution and the films of PBDTNS-FTAZ, PBDTBPS-FTAZ and ITIC.
Figure 1. Normalized absorption spectra of PBDTNS-FTAZ, PBDTBPS-FTAZ in o-DCB solution and the films of PBDTNS-FTAZ, PBDTBPS-FTAZ and ITIC.
Polymers 12 01673 g001
Polymers 12 01673 g002 550
Figure 2. (a) Electrochemical cyclic voltammograms of the two polymers, (b) the band structure of the device.
Figure 2. (a) Electrochemical cyclic voltammograms of the two polymers, (b) the band structure of the device.
Polymers 12 01673 g002
Polymers 12 01673 g003 550
Figure 3. (a) Device structure, (b) cross-sectional SEM images of the device. J–V curves of (c) PBDTNS-FTAZ:ITIC and (d) PBDTBPS-FTAZ:ITIC PSCs with different D:A ratios.
Figure 3. (a) Device structure, (b) cross-sectional SEM images of the device. J–V curves of (c) PBDTNS-FTAZ:ITIC and (d) PBDTBPS-FTAZ:ITIC PSCs with different D:A ratios.
Polymers 12 01673 g003
Polymers 12 01673 g004 550
Figure 4. (a,b) Normalized photovoltaic parameters aged in air for 192 h; (c) external quantum efficiency (EQE) spectra of devices based on PBDTNS-FTAZ and PBDTBPS-FTAZ.
Figure 4. (a,b) Normalized photovoltaic parameters aged in air for 192 h; (c) external quantum efficiency (EQE) spectra of devices based on PBDTNS-FTAZ and PBDTBPS-FTAZ.
Polymers 12 01673 g004
Polymers 12 01673 g005 550
Figure 5. Photocurrent density versus effective voltage (Jph-Veff) characteristics.
Figure 5. Photocurrent density versus effective voltage (Jph-Veff) characteristics.
Polymers 12 01673 g005
Polymers 12 01673 g006 550
Figure 6. The curve of current density versus incident light intensity.
Figure 6. The curve of current density versus incident light intensity.
Polymers 12 01673 g006
Polymers 12 01673 g007 550
Figure 7. AFM images of (a) PBDTNS-FTAZ:ITIC (b) PBDTBPS-FTAZ:ITIC and TEM images of (c) PBDTNS-FTAZ:ITIC and (d) PBDTBPS-FTAZ:ITIC.
Figure 7. AFM images of (a) PBDTNS-FTAZ:ITIC (b) PBDTBPS-FTAZ:ITIC and TEM images of (c) PBDTNS-FTAZ:ITIC and (d) PBDTBPS-FTAZ:ITIC.
Polymers 12 01673 g007
Table
Table 1. Device parameters of PBDTNS-FTAZ and PBDTBPS-FTAZ with different polymer:ITIC (D:A) ratios.
Table 1. Device parameters of PBDTNS-FTAZ and PBDTBPS-FTAZ with different polymer:ITIC (D:A) ratios.
PolymerD/A Ratios (w:w)Voc (V)Jsc (mA/cm2)FF (%)PCEmax (%)
PBDTNS-FTAZ1:10.88
(0.88 ± 0.01)		15.29
(14.83 ± 0.38)		60.39
(57.12 ± 2.36)		8.17
(7.85 ± 0.24)
1:1.50.87
(0.87 ± 0.01)		18.06
(17.74 ± 0.43)		61.21
(58.19 ± 2.27)		9.64
(9.23 ± 0.36)
1:20.85
(0.85 ± 0.01)		16.70
(16.18 ± 0.54)		45.68
(42.37 ± 3.61)		6.49
(6.12 ± 0.47)
PBDTBPS-FTAZ1:10.87
(0.87 ± 0.01)		14.52
(14.02 ± 0.39)		56.17
(53.89 ± 3.45)		7.08
(6.75 ± 0.31)
1:1.50.86
(0.86 ± 0.01)		16.24
(15.84 ± 0.41)		55.92
(53.86 ± 1.98)		7.79
(7.39 ± 0.56)
1:20.86
(0.86 ± 0.01)		14.82
(14.42 ± 0.58)		55.17
(53.73 ± 1.73)		7.07
(6.46 ± 0.59)
The average values are obtained from 10 devices.

Share and Cite

MDPI and ACS Style

Xie, R.; Song, L.; Zhao, Z. Comparing Benzodithiophene Unit with Alkylthionaphthyl and Alkylthiobiphenyl Side-Chains in Constructing High-Performance Nonfullerene Solar Cells. Polymers 2020, 12, 1673. https://doi.org/10.3390/polym12081673

AMA Style

Xie R, Song L, Zhao Z. Comparing Benzodithiophene Unit with Alkylthionaphthyl and Alkylthiobiphenyl Side-Chains in Constructing High-Performance Nonfullerene Solar Cells. Polymers. 2020; 12(8):1673. https://doi.org/10.3390/polym12081673

Chicago/Turabian Style

Xie, Ruyi, Li Song, and Zhihui Zhao. 2020. "Comparing Benzodithiophene Unit with Alkylthionaphthyl and Alkylthiobiphenyl Side-Chains in Constructing High-Performance Nonfullerene Solar Cells" Polymers 12, no. 8: 1673. https://doi.org/10.3390/polym12081673

APA Style

Xie, R., Song, L., & Zhao, Z. (2020). Comparing Benzodithiophene Unit with Alkylthionaphthyl and Alkylthiobiphenyl Side-Chains in Constructing High-Performance Nonfullerene Solar Cells. Polymers, 12(8), 1673. https://doi.org/10.3390/polym12081673

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop