Next Article in Journal
The Dispersion of Pulp-Fiber in High-Density Polyethylene via Different Fabrication Processes
Next Article in Special Issue
Comparative Investigation on the Performance of Modified System Poles and Traditional System Poles Obtained from PDC Data for Diagnosing the Ageing Condition of Transformer Polymer Insulation Materials
Previous Article in Journal
Nucleation Enhancement in Stereodefective Poly(l-lactide) by Free Volume Expansion Resulting from Low-Temperature Pressure CO2 Preconditioning
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Polymers
Volume 10
Issue 2
10.3390/polym10020121
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

Improving Photovoltaic Properties of P3HT:IC60BA through the Incorporation of Small Molecules

by
Binrui Xu
1,†,
Gopalan Sai-Anand
2,3,†,
Anantha-Iyengar Gopalan
4,
Qiquan Qiao
5 and
Shin-Won Kang
1,*
1
School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 80 Daehakro, Bukgu, Daegu 41566, Korea
2
Global Innovative Center for Advanced Nanomaterials, Faculty of Engineering and Built Environment, University of Newcastle, Callaghan, NSW 2298, Australia
3
Future Industries Institute, Division of Information Technology, Engineering and Environment, University of South Australia, Mawson Lakes, SA 5095, Australia
4
Research Institute of Advanced Energy Technology, Kyungpook National University, Daegu 41566, Korea
5
Center for Advanced Photovoltaics, Department of Electrical Engineering and Computer Science, South Dakota State University, Brookings, SD 570007, USA
*
Author to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Polymers 2018, 10(2), 121; https://doi.org/10.3390/polym10020121
Submission received: 8 January 2018 / Revised: 22 January 2018 / Accepted: 24 January 2018 / Published: 26 January 2018
(This article belongs to the Special Issue Polymers for Energy Applications)
Browse Figures
Versions Notes

Abstract

:
We investigated the role of a functional solid additive, 2,3-dihydroxypyridine (DHP), in influencing the optoelectronic, morphological, structural and photovoltaic properties of bulk-heterojunction-based polymer solar cells (BHJ PSCs) fabricated using poly(3-hexylthiophene): indene-C60 bisadduct (P3HT:IC60BA) photoactive medium. A dramatic increase in the power conversion efficiency (~20%) was witnessed for the BHJ PSCs treated with DHP compared to the pristine devices. A plausible explanation describing the alignment of pyridine moieties of DHP with the indene side groups of IC60BA is presented with a view to improving the performance of the BHJ PSCs via improved crystalline order and hydrophobicity changes.

Graphical Abstract

1. Introduction

Bulk-heterojunction polymer solar cells (BHJ PSCs) are considered prospective candidates for renewable energy technology, owing to their functionalities in new devices, and multiple advantages such as ease of fabrication, low cost, light weight, and roll-to-roll compatibility [1,2,3]. Single-junction BHJ PSCs have achieved a power conversion efficiency (PCE) in excess of 11% [4]. In the process of enhancing the PCE and overcoming the problem (a lower open-circuit voltage (Voc) of ~0.6 V) associated with the use of poly(3-hexylthiophene): [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM)blend, Li et al. demonstrated the use of an indene-C60 bisadduct (IC60BA) as the electron acceptor in the BHJ PSCs [5]. The PSCs based on P3HT:IC60BA (Scheme 1) pairs showed a significant Voc of 0.84 V and a higher PCE [6,7,8]. However, further research exploring the potential of IC60BA to achieve high-performance PSCs is continuing [9,10,11]. The manipulation of active layer nanoscale morphology with optimal phase separation and bi-continuous interpenetrated donor/acceptor 3D networks can be achieved through the inclusion of processing additives (e.g., n-octylthiol [12], 1,8-diiodooctane [13], 1-chloronaphthalene [14], N-methyl-2-pyrrolidone [15], 1,8-octanedithiol [16], maleic anhydride [17], etc.) to accentuate the efficiency of BHJ PSCs [18]. The functional roles of the selected additives, such as their boiling point, and the nature of their interaction with the donor or acceptor in the photoactive blend, play key roles in the nanomorphology, crystallinity of the components, mobility, photocurrent, and PCE of the PSC [19,20]. A literature search reveals that the exploration of functional additives to optimize the morphology of the bis-adduct fullerene-based binary systems and optoelectronic properties has only sporadically been reported, and hence is worthy of in-depth investigation [21,22].
In this work, we focus on the optimization of the P3HT:IC60BA blend system by introducing a functional additive, 2,3-dihydroxypyridine (DHP, shown in Scheme 1) to generate a ternary P3HT:IC60BA:DHP blend system [23,24,25] and improve the PV performance of BHJ PSCs in a standard device geometry: glass/ITO/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/P3HT:IC60BA:DHP/zinc oxide nanocrystals (ZnO NCs)/Al (Figure 1A) [26,27,28]. The selection of DHP takes into account its chemical structure (cyclic 6-π electron and presence of an electronegative nitrogen atom in the ring) and multifunctional properties (pKa = 5, pH  =  8.22, a proton acceptor and intermolecular hydrogen bonding, as well as intermolecular hydrogen bond formation due to the presence of two hydroxyl groups) [29]. Therefore, it is reasonable to assume that the pyridine in DHP can form π–π interaction with the thiophene ring in P3HT, and the DHP molecule can form intermolecular hydrogen bond with IC60BA. These interactions could lead to optimal phase separation between P3HT and IC60BA, and modify the morphology of P3HT:IC60BA:DHP. Figure 1B depicts the energy level band gap of the studied materials. After the incorporation of DHP into P3HT:IC60BA system, the PCE of the fabricated BHJ PSCs with the ternary blend system exhibited a significant increase in PCE (~20%) as compared to the parent device. Herein, we present the details of our investigation of role of DHP towards influencing the optical, microstructural, morphological and PV properties of BHJ PSCs [30,31].

2. Experimental Section

2.1. Materials

PEDOT:PSS (Clevios P VP AI. 4083, H.C. Starck, Inc., Newton, MA, USA), P3HT (molecular weight (MW) = 4500, Luminescence Technology Corp., Taiwan, China), IC60BA (MW = 953.40, Luminescence Technology Corp., Taiwan, China), 1,2-dichlorobenzene (DCB) (99%, Sigma-Aldrich, Seoul, Korea), 2,3-dihydroxypyridine (DHP, 99%, Tokyo Chemical Industry Corp., Ltd., Tokyo, Japan).

2.2. Fabrication of the BHJ PSCs

P3HT, IC60BA and DHP were dissolved in DCB in a 1:1:0.5 weight ratio and stirred overnight at 60 °C to prepare a photoactive ink solution. The as-prepared ink was spin-coated on a pre-formed ITO/PEDOT: PSS (30 ± 5 nm) film at 600 rpm for 60 s, to fabricate a desired thickness (~250 nm) [32]. The as-cast films were then solvent-annealed in a sealed glass petri dish kept in a customized box for a few hours, and a protective layer of ZnO NCs was deposited on top to passivate the photoactive layer [8,33,34]. After edge beading with acetone, an aluminum cathode (~150 nm) was thermally evaporated onto the device stack inside a vacuum chamber. The active area of the device was 9 mm2. Finally, the fabricated devices were post-annealed at 150 °C for 10 min to improve the interfacial characteristics [35]. All the film deposition steps were performed in an open-air atmosphere with a relative humidity of 15–25%.

2.3. Measurements and Characterization

A light source integrated with a 300-W Xenon arc lamp (XES-300S1, SAN-EI Electric Corp., Osaka, Japan) with an illumination and a computer-controlled source meter (2400 series, Keithley, Inc., Seoul, Korea) were used to measure the PV performance parameters of BHJ PSCs under standard AM 1.5 G illumination (100 mW·cm−2). UV–Vis absorption spectra were obtained using a UV–Vis spectrophotometer (Shimadzu Corp., Kyoto, Japan). The crystallinity characteristics were studied using a X-ray diffractometer (D/Max-2500, Rigaku Corp., Beijing, China). Atomic force microscopy (AFM) images were probed to understand the modified donor-acceptor morphology using a scanning probe microscope (Model 5500, Agilent Technologies, Inc., Santa Clara, CA, USA) and analyzed with the software Park Systems XEI (Park Systems, Suwon, Korea). Photoluminescence (PL) spectra of the films were recorded using a PL spectrophotometer (Spectra pro 2150i, Acton Research Corp., Acton, MA, USA). A drop shape analyzer (Kruss, Hamburg, Germany) was utilized to measure the contact angles. The thickness of the active layer was measured by Field Emission Scanning Electron Microscopy (Hitachi SU8220, Tokyo, Japan).

3. Results and Discussion

3.1. Optical, Structural and Morphological Properties

The absorption spectra of P3HT:IC60BA and P3HT:IC60BA:DHP thin films are shown in Figure 2A. The characteristic vibronic peaks are observed at 510, 550 and 603 nm, while the absorbance of the P3HT:IC60BA:DHP was significantly enhanced in the same visible region [36,37]. The peak at 510 nm is assigned to the intrachain π–π transitions of P3HT blocks. The two vibronic shoulders at 550 nm and 603 nm can be attributed to the π–π stacking structure of P3HT [38,39]. In general, the optical absorption intensity of a conjugated polymer increases with increasing crystallinity and conjugation chain length [40]. Therefore, the observed increase in absorbance can be attributed to the higher degree of P3HT crystallinity and extended P3HT conjugation length, which is consistent with the X-ray diffraction (XRD) results [41,42]. As shown in Figure 2B, the XRD pattern exhibits a significantly enhanced diffraction peak at 2θ = 5.52°, which corresponds to the (100) reflection peak of P3HT [37]. The inclusion of DHP into P3HT:IC60BA resulted in a clear increase in crystallinity, structural ordering, larger P3HT crystal domain size, and possible re-distribution of the photoactive components (Figure 2B). We believe that the indene side groups in IC60BA align parallel to the pyridine moieties of DHP, allowing the conjugate backbone of P3HT to interact with conjugated fullerene cage. As a consequence, a more ordered and dense packing structure for P3HT can be expected.
The PV performance is related to the nanomorphology of the active layer. To investigate how the inclusion of DHP influences the active layer morphology, AFM images of the ITO/PEDOT:PSS/P3HT:IC60BA and ITO/PEDOT:PSS/P3HT:IC60BA:DHP (Figure 3A–D) and its corresponding thermally annealed counterparts (Figure 3E–H) were probed [43]. The root mean square (RMS) roughness value determined for the ternary P3HT:IC60BA:DHP blended film was 16.1 nm, which is higher than that of the P3HT:IC60BA (5.1 nm) [44]. In fact, 16.1 nm is quite close to the optimal domain size (10~20 nm) of P3HT for the improved exciton dissociation [45]. The increase in surface roughness arises from self-assembled P3HT and IC60BA domains due to possible molecular-level interactions with DHP and solvent annealing [41]. In the presence of the DHP, optimal phase separation was achieved with a 3D interpenetrating network, enabling improved exciton dissociation and charge transport [46,47]. Compared to the film without DHP, the RMS roughness of the modified film increased from 6.8 nm to 17.1 nm after annealing at 150 °C for 10 min. While the surface of the P3HT:IC60BA film is richer in P3HT, the top surface of P3HT:IC60BA:DHP film is dominated by the presence of IC60BA domains. The preferential existence of IC60BA at the surface of P3HT:IC60BA:DHP would enhance the hydrophobicity at the interface.
We investigated the surface characteristics through water contact angle measurements (Figure 4). The P3HT:IC60BA:DHP surface is relatively hydrophobic, giving rise to a contact angle of 90.0°, while the surface of P3HT:IC60BA is less hydrophobic with a contact angle of 82.1°. The literature suggests that the surface tension of P3HT is much lower than that of IC60BA. These two factors are in accordance with the predominance of fullerene (IC60BA) rich phase at the P3HT:IC60BA:DHP surface [48]. The increased contact angle of the P3HT:IC60BA:DHP confirms the improved hydrophobicity and re-distributions of the polymer and fullerene components in the ternary blended film. We attribute that the entropic effects resulted from the differences in the flexibilities of P3HT chains and crystallization behavior lead to the preferential segregation of IC60BA at the top surface of DHP treated active layer.

3.2. Photovoltaic Properties

To validate the efficiency of the ternary P3HT:IC60BA:DHP blend system, current density-voltage (J–V) curves were recorded under AM 1.5 G illumination at 100 mW·cm−2 and the performance of the BHJ PSCs with and without the additive are shown in Figure 5A, Table 1. The pristine device without DHP exhibited a PCE of 4.22%, with an open-circuit voltage (Voc) of 0.83, a short current density (Jsc) of 8.36 mA·cm−2, a fill factor (FF) of 0.63, and a series resistance (Rs) of 160 Ω. By introducing DHP into P3HT:IC60BA, PCE, Jsc and FF were significantly improved and Rs relatively decreased, while Voc nearly maintained the same value compared to the pristine device. The best PCE of 5.06% was achieved at the optimized weight ratio of 0.5 wt % DHP into the P3HT:IC60BA, with Voc, Jsc, FF and Rs values of 0.83 V, 9.39 mA·cm−2, 0.66 and 129 Ω, respectively [49,50]. The observed improvement in the PCE is mainly related to the enhanced Jsc and reduced Rs, which are ascribed to the optimized morphology, enhanced crystallinity of P3HT and improved light absorption of P3HT:IC60BA film with the addition of 0.5 wt % DHP.
In order to investigate charge separation and recombination dynamics of the active layer, steady state PL spectra of the P3HT:IC60BA and P3HT:IC60BA:DHP films (Figure 5B) were acquired by exciting at 600 nm [51,52]. The peak due to P3HT at ~624 nm is significantly quenched for P3HT:IC60BA:DHP as compared to the P3HT:IC60BA, resulting in efficient exciton dissociation between P3HT and IC60BA [53]. Furthermore, the space charge limited current (SCLC) method was used to confirm the improved hole mobility of P3HT:IC60BA and P3HT:IC60BA:DHP-based devices [54,55]. With the fabricated hole-only devices (glass/ITO/PEDOT:PSS/active blend/Au), the hole mobility values of binary P3HT:IC60BA and ternary P3HT:IC60BA:DHP blends were calculated as 2.15 × 10−4 and 8.56 × 10−4 cm2·(Vs)−1, respectively [56]. Therefore, the addition of DHP in P3HT:IC60BA facilitates balanced carrier mobility as compared to P3HT:IC60BA [57].

4. Conclusions

In summary, the BHJ PSCs fabricated with the P3HT:IC60BA active layer containing 0.5 wt % DHP exhibited a remarkable (~20%) increase in the PCE as compared to PSC based on the control devices. This improvement is attributed to the increased crystallinity, as well as the synergistic influence of the improved optical, microstructural, and optoelectronic properties, of the photosensitive layer. This study provides an inspiration and scope for the researchers aiming to improve the overall efficiency of any BHJ PSC system through a judicious selection of components (additives/dopants etc.) having multifunctional capabilities.

Supplementary Materials

The following are available online at https://www.mdpi.com/2073-4360/10/2/121/s1, Figure S1: FE-SEM cross-section image of the completed device with the structure of glass/ITO/PEDOT:PSS/P3HT:ICBA:DHP/ZnO NCs/Al.

Acknowledgments

This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korea Government (MSIP) (No. NRF 2017R1D1A3B03032042), the BK21 Plus project funded by the Ministry of Education, Korea (21A20131600011) and China Scholarship Council (CSC, No. 201708260004).

Author Contributions

Gopalan Sai-Anand and Binrui Xu conceived the idea, designed and performed the experiments. Data interpretations were done by Binrui Xu, Gopalan Sai-Anand, Qiquan Qiao and Anantha-Iyengar Gopalan. Shin-Won Kang guided the project.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. 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] [PubMed]
  2. Venkatesan, S.; Ngo, E.; Khatiwada, D.; Zhang, C.; Qiao, Q. Enhanced lifetime of polymer solar cells by surface passivation of metal oxide buffer layers. ACS Appl. Mater. Interfaces 2015, 7, 16093–16100. [Google Scholar] [CrossRef] [PubMed]
  3. Li, G.; Zhu, R.; Yang, Y. Polymer solar cells. Nat. Photonics 2012, 6, 153–161. [Google Scholar] [CrossRef]
  4. Liu, C.; Yi, C.; Wang, K.; Yang, Y.; Bhatta, R.S.; Tsige, M.; Xiao, S.; Gong, X. Single-junction polymer solar cells with over 10% efficiency by a novel two-dimensional donor-acceptor conjugated copolymer. ACS Appl. Mater. Interfaces 2015, 7, 4928–4935. [Google Scholar] [CrossRef] [PubMed]
  5. He, Y.; Chen, H.-Y.; Hou, J.; Li, Y. Indene-C60 bisadduct: A new acceptor for high-performance polymer solar cells. J. Am. Chem. Soc. 2010, 132, 1377–1382. [Google Scholar] [CrossRef] [PubMed]
  6. Loew, N.; Komatsu, S.; Akita, H.; Funayama, K.; Yuge, T.; Fujiwara, T.; Ihara, M. TiO2 as electron-extraction-layer in reverse type P3HT/ICBA organic solar cells. ECS Trans. 2014, 58, 77–88. [Google Scholar] [CrossRef]
  7. Petrović, A.; Gojanović, J.; Matavulj, P.; Islam, M.; Živanović, S. Temperature dependence of P3HT: ICBA polymer solar cells. In Proceedings of the International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD), Copenhagen, Denmark, 24–28 July 2017; pp. 133–134. [Google Scholar]
  8. Gopalan, S.-A.; Gopalan, A.-I.; Vinu, A.; Lee, K.-P.; Kang, S.-W. A new optical-electrical integrated buffer layer design based on gold nanoparticles tethered thiol containing sulfonated polyaniline towards enhancement of solar cell performance. Sol. Energy Mater. Sol. Cells 2018, 174, 112–123. [Google Scholar] [CrossRef]
  9. Cheng, F.; Fang, G.; Fan, X.; Huang, H.; Zheng, Q.; Qin, P.; Lei, H.; Li, Y. Enhancing the performance of P3HT:ICBA based polymer solar cells using LIF as electron collecting buffer layer and UV–ozone treated MoO3 as hole collecting buffer layer. Sol. Energy Mater. Sol. Cells 2013, 110, 63–68. [Google Scholar] [CrossRef]
  10. Venkatesan, S.; Chen, J.; Ngo, E.C.; Dubey, A.; Khatiwada, D.; Zhang, C.; Qiao, Q. Critical role of domain crystallinity, domain purity and domain interface sharpness for reduced bimolecular recombination in polymer solar cells. Nano Energy 2015, 12, 457–467. [Google Scholar] [CrossRef]
  11. Nemnes, G.A.; Iftimie, S.; Palici, A.; Nicolaev, A.; Mitran, T.L.; Radu, A.; Antohe, S. Optimization of the structural configuration of ICBA/P3HT photovoltaic cells. Appl. Surf. Sci. 2017, 424, 264–268. [Google Scholar] [CrossRef]
  12. Peet, J.; Soci, C.; Coffin, R.C.; Nguyen, T.Q.; Mikhailovsky, A.; Moses, D.; Bazan, G.C. Method for increasing the photoconductive response in conjugated polymer/fullerene composites. Appl. Phys. Lett. 2006, 89, 252105. [Google Scholar] [CrossRef]
  13. Jacobs, I.E.; Wang, F.; Bedolla Valdez, Z.I.; Ayala Oviedo, A.N.; Bilsky, D.J.; Moule, A.J. Photoinduced degradation from trace 1,8-diiodooctane in organic photovoltaics. J. Mater. Chem. C 2018, 6, 219–225. [Google Scholar] [CrossRef]
  14. Guo, C.; Lee, Y.; Lin, Y.-H.; Strzalka, J.; Wang, C.; Hexemer, A.; Jaye, C.; Fischer, D.A.; Verduzco, R.; Wang, Q.; et al. Photovoltaic performance of block copolymer devices is independent of the crystalline texture in the active layer. Macromolecules 2016, 49, 4599–4608. [Google Scholar] [CrossRef]
  15. Yao, Y.; Hou, J.; Xu, Z.; Li, G.; Yang, Y. Effects of solvent mixtures on the nanoscale phase separation in polymer solar cells. Adv. Funct. Mater. 2008, 18, 1783–1789. [Google Scholar] [CrossRef]
  16. Guo, X.; Zhang, M.; Ma, W.; Zhang, S.; Hou, J.; Li, Y. Effect of solvent additive on active layer morphologies and photovoltaic performance of polymer solar cells based on PBDTTT-C-T/PC71BM. RSC Adv. 2016, 6, 51924–51931. [Google Scholar] [CrossRef]
  17. Konkin, A.; Ritter, U.; Scharff, P.; Schrödner, M.; Sensfuss, S.; Aganov, A.; Klochkov, V.; Ecke, G. Improvement of P3HT–ICBA solar cell photovoltaic characteristics due to the incorporation of the maleic anhydride additive: P3HT morphology study of P3HT–ICBA and P3HT–ICBA–MA films by means of X-band LESR. Synth. Met. 2014, 197, 210–216. [Google Scholar] [CrossRef]
  18. Kim, Y.; Lim, E. Development of polymer acceptors for organic photovoltaic cells. Polymers 2014, 6, 382–407. [Google Scholar] [CrossRef]
  19. Gopalan, S.-A.; Seo, M.-H.; Anantha-Iyengar, G.; Han, B.; Lee, S.-W.; Kwon, D.-H.; Lee, S.-H.; Kang, S.-W. Mild wetting poor solvent induced hydrogen bonding interactions for improved performance in bulk heterojunction solar cells. J. Mater. Chem. A 2014, 2, 2174–2186. [Google Scholar] [CrossRef]
  20. Wang, Y.; Shi, Z.; Liu, H.; Wang, F.; Bai, Y.; Bian, X.; Zhang, B.; Hayat, T.; Alsaedi, A.; Tan, Z.A. The effect of donor and nonfullerene acceptor inhomogeneous distribution within the photoactive layer on the performance of polymer solar cells with different device structures. Polymers 2017, 9, 571. [Google Scholar] [CrossRef]
  21. Pham, V.H.T.; Truong, N.T.N.; Trinh, T.K.; Lee, S.H.; Park, C. Controlling the morphology of the active layer by using additives and its effect on bulk hetero-junction solar cell performance. Korean J. Chem. Eng. 2016, 33, 678–682. [Google Scholar] [CrossRef]
  22. Zhu, X.; Lu, K.; Xia, B.; Fang, J.; Zhao, Y.; Zhao, T.; Wei, Z.; Jiang, L. Improving the performances of random copolymer based organic solar cells by adjusting the film features of active layers using mixed solvents. Polymers 2016, 8, 4. [Google Scholar] [CrossRef]
  23. Ameri, T.; Khoram, P.; Min, J.; Brabec, C.J. Organic ternary solar cells: A review. Adv. Mater. 2013, 25, 4245–4266. [Google Scholar] [CrossRef] [PubMed]
  24. Lu, L.; Xu, T.; Chen, W.; Landry, E.S.; Yu, L. Ternary blend polymer solar cells with enhanced power conversion efficiency. Nat. Photonics 2014, 8, 716–722. [Google Scholar] [CrossRef]
  25. Stylianakis, M.M.; Konios, D.; Viskadouros, G.; Vernardou, D.; Katsarakis, N.; Koudoumas, E.; Anastasiadis, S.H.; Stratakis, E.; Kymakis, E. Ternary organic solar cells incorporating zinc phthalocyanine with improved performance exceeding 8.5%. Dyes Pigments 2017, 146, 408–413. [Google Scholar] [CrossRef]
  26. Neupane, U.; Bahrami, B.; Biesecker, M.; Baroughi, M.F.; Qiao, Q. Kinetic Monte Carlo modeling on organic solar cells: Domain size, donor-acceptor ratio and thickness. Nano Energy 2017, 35, 128–137. [Google Scholar] [CrossRef]
  27. Mitul, A.F.; Mohammad, L.; Venkatesan, S.; Adhikari, N.; Sigdel, S.; Wang, Q.; Dubey, A.; Khatiwada, D.; Qiao, Q. Low temperature efficient interconnecting layer for tandem polymer solar cells. Nano Energy 2015, 11, 56–63. [Google Scholar] [CrossRef]
  28. Lu, L.; Kelly, M.A.; You, W.; Yu, L. Status and prospects for ternary organic photovoltaics. Nat. Photonics 2015, 9, 491–500. [Google Scholar] [CrossRef]
  29. Xu, B.; Gopalan, S.-A.; Gopalan, A.-I.; Muthuchamy, N.; Lee, K.-P.; Lee, J.-S.; Jiang, Y.; Lee, S.-W.; Kim, S.-W.; Kim, J.-S.; et al. Functional solid additive modified PEDOT:PSS as an anode buffer layer for enhanced photovoltaic performance and stability in polymer solar cells. Sci. Rep. 2017, 7, 45079. [Google Scholar] [CrossRef] [PubMed]
  30. Lu, L.; Chen, W.; Xu, T.; Yu, L. High-performance ternary blend polymer solar cells involving both energy transfer and hole relay processes. Nat. Commun. 2015, 6, 7327. [Google Scholar] [CrossRef] [PubMed]
  31. Minas, M.S.; Dimitrios, K.; Constantinos, P.; George, K.; Emmanuel, S.; Emmanuel, K. Ternary solution-processed organic solar cells incorporating 2D materials. 2D Mater. 2017, 4, 042005. [Google Scholar]
  32. Sai-Anand, G.; Han, B.; Kang, B.-H.; Kim, S.-W.; Lee, S.-W.; Lee, J.-S.; Jeong, H.-M.; Kang, S.-W. Incorporation of gold nanodots into poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) for an efficient anode interfacial layer for improved plasmonic organic photovoltaics. J. Nanosci. Nanotechnol. 2015, 15, 7092–7098. [Google Scholar] [CrossRef] [PubMed]
  33. Li, G.; Yao, Y.; Yang, H.; Shrotriya, V.; Yang, G.; Yang, Y. “Solvent annealing” effect in polymer solar cells based on poly(3-hexylthiophene) and methanofullerenes. Adv. Funct. Mater. 2007, 17, 1636–1644. [Google Scholar] [CrossRef]
  34. He, Z.; Liu, F.; Wang, C.; Chen, J.; He, L.; Nordlund, D.; Wu, H.; Russell, T.P.; Cao, Y. Simultaneous spin-coating and solvent annealing: Manipulating the active layer morphology to a power conversion efficiency of 9.6% in polymer solar cells. Mater. Horiz. 2015, 2, 592–597. [Google Scholar] [CrossRef]
  35. Kumar, P.; Bilen, C.; Feron, K.; Zhou, X.; Belcher, W.J.; Dastoor, P.C. Enhanced regeneration of degraded polymer solar cells by thermal annealing. Appl. Phys. Lett. 2014, 104, 193905. [Google Scholar] [CrossRef]
  36. Parenti, F.; Tassinari, F.; Libertini, E.; Lanzi, M.; Mucci, A. Π-stacking signature in NMR solution spectra of thiophene-based conjugated polymers. ACS Omega 2017, 2, 5775–5784. [Google Scholar] [CrossRef]
  37. Sai-Anand, G.; Gopalan, A.-I.; Lee, K.-P.; Venkatesan, S.; Kang, B.-H.; Lee, S.-W.; Lee, J.-S.; Qiao, Q.; Kwon, D.-H.; Kang, S.-W. A futuristic strategy to influence the solar cell performance using fixed and mobile dopants incorporated sulfonated polyaniline based buffer layer. Sol. Energy Mater. Sol. Cells 2015, 141, 275–290. [Google Scholar] [CrossRef]
  38. Bertinelli, F.; Costa-Bizzarri, P.; Della-Casa, C.; Lanzi, M. Analysis of UV–Vis spectral profiles of solvatochromic poly[3-(10-hydroxydecyl)-2,5-thienylene]. Spectrochim. Acta A 2002, 58, 583–592. [Google Scholar] [CrossRef]
  39. Müllerová, J.; Kaiser, M.; Nádaždy, V.; Šiffalovič, P.; Majková, E. Optical absorption study of P3HT:PCBM blend photo-oxidation for bulk heterojunction solar cells. Sol. Energy 2016, 134, 294–301. [Google Scholar] [CrossRef]
  40. Sai-Anand, G.; Gopalan, A.-I.; Lee, K.-P.; Venkatesan, S.; Qiao, Q.; Kang, B.-H.; Lee, S.-W.; Lee, J.-S.; Kang, S.-W. Electrostatic nanoassembly of contact interfacial layer for enhanced photovoltaic performance in polymer solar cells. Sol. Energy Mater. Sol. Cells 2016, 153, 148–163. [Google Scholar] [CrossRef]
  41. Kadem, B.; Hassan, A. The effect of fullerene derivatives ratio on P3HT-based organic solar cells. Energy Procedia 2015, 74, 439–445. [Google Scholar] [CrossRef]
  42. Gao, D.; Djukic, B.; Shi, W.; Bridges, C.R.; Kozycz, L.M.; Seferos, D.S. Evolution of the electron mobility in polymer solar cells with different fullerene acceptors. ACS Appl. Mater. Interfaces 2013, 5, 8038–8043. [Google Scholar] [CrossRef] [PubMed]
  43. Xie, Y.; Bao, Y.; Du, J.; Jiang, C.; Qiao, Q. Understanding of morphology evolution in local aggregates and neighboring regions for organic photovoltaics. Phys. Chem. Chem. Phys. 2012, 14, 10168–10177. [Google Scholar] [CrossRef] [PubMed]
  44. Liao, H.-C.; Chen, P.-H.; Chang, R.; Su, W.-F. Morphological control agent in ternary blend bulk heterojunction solar cells. Polymers 2014, 6, 2784–2802. [Google Scholar] [CrossRef]
  45. Kim, B.; Ma, B.; Donuru, V.R.; Liu, H.; Frechet, J.M.J. Bodipy-backboned polymers as electron donor in bulk heterojunction solar cells. Chem. Commun. 2010, 46, 4148–4150. [Google Scholar] [CrossRef] [PubMed]
  46. Leclerc, N.; Chávez, P.; Ibraikulov, O.; Heiser, T.; Lévêque, P. Impact of backbone fluorination on π-conjugated polymers in organic photovoltaic devices: A review. Polymers 2016, 8, 11. [Google Scholar] [CrossRef]
  47. Cao, T.; Chen, N.; Liu, G.; Wan, Y.; Perea, J.D.; Xia, Y.; Wang, Z.; Song, B.; Li, N.; Li, X.; et al. Towards a full understanding of regioisomer effects of indene-C60 bisadduct acceptors in bulk heterojunction polymer solar cells. J. Mater. Chem. A 2017, 5, 10206–10219. [Google Scholar] [CrossRef]
  48. Cho, H.-H.; Cho, C.-H.; Kang, H.; Yu, H.; Oh, J.H.; Kim, B.J. Molecular structure-device performance relationship in polymer solar cells based on indene-C60 bis-adduct derivatives. Korean J. Chem. Eng. 2015, 32, 261–267. [Google Scholar] [CrossRef]
  49. Zeng, H.; Zhu, X.; Liang, Y.; Guo, X. Interfacial layer engineering for performance enhancement in polymer solar cells. Polymers 2015, 7, 333–372. [Google Scholar] [CrossRef]
  50. Yang, S.; Sun, X.; Zhang, Y.; Li, G.; Zhao, X.; Li, X.; Fu, G. Enhancing the efficiency of polymer solar cells by modifying buffer layer with N,N-dimethylacetamide. Int. J. Photoenergy 2014, 2014. [Google Scholar] [CrossRef]
  51. Kumar, M.; Dubey, A.; Reza, K.M.; Adhikari, N.; Qiao, Q.; Bommisetty, V. Origin of photogenerated carrier recombination at the metal-active layer interface in polymer solar cells. Phys. Chem. Chem. Phys. 2015, 17, 27690–27697. [Google Scholar] [CrossRef] [PubMed]
  52. Solanki, A.; Wu, B.; Salim, T.; Lam, Y.M.; Sum, T.C. Correlation between blend morphology and recombination dynamics in additive-added P3HT:PCBM solar cells. Phys. Chem. Chem. Phys. 2015, 17, 26111–26120. [Google Scholar] [CrossRef] [PubMed]
  53. Huang, J.-H.; Hsiao, Y.-S.; Richard, E.; Chen, C.-C.; Chen, P.; Li, G.; Chu, C.-W.; Yang, Y. The investigation of donor-acceptor compatibility in bulk-heterojunction polymer systems. Appl. Phys. Lett. 2013, 103, 043304. [Google Scholar] [CrossRef]
  54. Hsiow, C.-Y.; Wang, H.-Y.; Lin, Y.-H.; Raja, R.; Rwei, S.-P.; Chiu, W.-Y.; Dai, C.-A.; Wang, L. Synthesis and characterization of two-dimensional conjugated polymers incorporating electron-deficient moieties for application in organic photovoltaics. Polymers 2016, 8, 382. [Google Scholar] [CrossRef]
  55. Van der Kaap, N.J.; Koster, L.J.A. Charge carrier thermalization in organic diodes. Sci. Rep. 2016, 6, 19794. [Google Scholar] [CrossRef] [PubMed]
  56. Han, B.; Gopalan, S.-A.; Lee, K.-D.; Kang, B.-H.; Lee, S.-W.; Lee, J.-S.; Kwon, D.-H.; Lee, S.-H.; Kang, S.-W. Preheated solvent exposure on P3HT:PCBM thin film: A facile strategy to enhance performance in bulk heterojunction photovoltaic cells. Curr. Appl. Phys. 2014, 14, 1443–1450. [Google Scholar] [CrossRef]
  57. Liu, C.; Li, Z.; Zhang, Z.; Zhang, X.; Shen, L.; Guo, W.; Zhang, L.; Long, Y.; Ruan, S. Improving the charge carrier transport of organic solar cells by incorporating a deep energy level molecule. Phys. Chem. Chem. Phys. 2017, 19, 245–250. [Google Scholar] [CrossRef] [PubMed]
Polymers 10 00121 sch001 550
Scheme 1. Chemical structures of P3HT, IC60BA and DHP.
Scheme 1. Chemical structures of P3HT, IC60BA and DHP.
Polymers 10 00121 sch001
Polymers 10 00121 g001 550
Figure 1. (A) Device schematic and (B) energy level band diagram.
Figure 1. (A) Device schematic and (B) energy level band diagram.
Polymers 10 00121 g001
Polymers 10 00121 g002 550
Figure 2. (A) Absorption spectra of (a) P3HT:IC60BA and (b) P3HT:IC60BA:DHP thin films, and (B) XRD patterns of (a) P3HT:IC60BA and (b) P3HT:IC60BA:DHP films.
Figure 2. (A) Absorption spectra of (a) P3HT:IC60BA and (b) P3HT:IC60BA:DHP thin films, and (B) XRD patterns of (a) P3HT:IC60BA and (b) P3HT:IC60BA:DHP films.
Polymers 10 00121 g002
Polymers 10 00121 g003a 550Polymers 10 00121 g003b 550
Figure 3. (A,B) AFM images of the P3HT:IC60BA and P3HT:IC60BA:DHP films without thermal annealing, (C,D) AFM images of the P3HT:IC60BA and P3HT:IC60BA:DPH films annealed at 150 °C for 10 min, (E,F) 3D AFM images of the P3HT:IC60BA and P3HT:IC60BA:DHP films without thermal annealing, and (G,H) 3D AFM images of P3HT:IC60BA and P3HT:IC60BA:DPH films annealed at 150 °C for 10 min.
Figure 3. (A,B) AFM images of the P3HT:IC60BA and P3HT:IC60BA:DHP films without thermal annealing, (C,D) AFM images of the P3HT:IC60BA and P3HT:IC60BA:DPH films annealed at 150 °C for 10 min, (E,F) 3D AFM images of the P3HT:IC60BA and P3HT:IC60BA:DHP films without thermal annealing, and (G,H) 3D AFM images of P3HT:IC60BA and P3HT:IC60BA:DPH films annealed at 150 °C for 10 min.
Polymers 10 00121 g003aPolymers 10 00121 g003b
Polymers 10 00121 g004 550
Figure 4. Water droplet contact angles of (A) P3HT:IC60BA and (B) P3HT:IC60BA:DHP.
Figure 4. Water droplet contact angles of (A) P3HT:IC60BA and (B) P3HT:IC60BA:DHP.
Polymers 10 00121 g004
Polymers 10 00121 g005 550
Figure 5. (A) J–V characteristics of the BHJ PSCs fabricated with (a) P3HT:IC60BA and (b) P3HT:IC60BA:DHP-based BHJ PSC, and (B) PL spectra of (a) P3HT:IC60BA and (b) P3HT:IC60BA:DHP thin films.
Figure 5. (A) J–V characteristics of the BHJ PSCs fabricated with (a) P3HT:IC60BA and (b) P3HT:IC60BA:DHP-based BHJ PSC, and (B) PL spectra of (a) P3HT:IC60BA and (b) P3HT:IC60BA:DHP thin films.
Polymers 10 00121 g005
Table
Table 1. Summary of the photovoltaic performance parameters of the BHJ PSCs fabricated with P3HT:IC60BA and P3HT:IC60BA:DHP. The average PCE values were obtained from eight independent devices.
Table 1. Summary of the photovoltaic performance parameters of the BHJ PSCs fabricated with P3HT:IC60BA and P3HT:IC60BA:DHP. The average PCE values were obtained from eight independent devices.
BHJ PSCVoc (V)Jsc (mA/cm2)Rs (Ω)FFPCEE (%)
P3HT:IC60BA0.83 ± 0.0138.36 ± 0.32160 ± 23.980.63 ± 0.0204.22 ± 0.13
P3HT:IC60BA:DHP0.83 ± 0.039.39 ± 0.09129 ± 4.040.66 ± 0.0065.06 ± 0.05

Share and Cite

MDPI and ACS Style

Xu, B.; Sai-Anand, G.; Gopalan, A.-I.; Qiao, Q.; Kang, S.-W. Improving Photovoltaic Properties of P3HT:IC60BA through the Incorporation of Small Molecules. Polymers 2018, 10, 121. https://doi.org/10.3390/polym10020121

AMA Style

Xu B, Sai-Anand G, Gopalan A-I, Qiao Q, Kang S-W. Improving Photovoltaic Properties of P3HT:IC60BA through the Incorporation of Small Molecules. Polymers. 2018; 10(2):121. https://doi.org/10.3390/polym10020121

Chicago/Turabian Style

Xu, Binrui, Gopalan Sai-Anand, Anantha-Iyengar Gopalan, Qiquan Qiao, and Shin-Won Kang. 2018. "Improving Photovoltaic Properties of P3HT:IC60BA through the Incorporation of Small Molecules" Polymers 10, no. 2: 121. https://doi.org/10.3390/polym10020121

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