| 1. |
- Peng, Zuosheng, et al.
(författare)
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One-step coating inverted polymer solar cells using a conjugated polymer as an electron extraction additive
- 2015
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Ingår i: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 3:41, s. 20500-20507
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Tidskriftsartikel (refereegranskat)abstract
- We report a facile technique of blending a conjugated polymer thieno[3,4-b]thiophene/benzodithiophene (PTB7):[6,6]-phenyl-C71-butyric acid methyl ester (PCBM[70]) active materials with a conjugated interfacial modification polymer poly[(9,9-bis(3-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) to simplify the coating process and improve the bulk heterojunction (BHJ) polymer solar cell (PSC) performance. The reason for and result of PFN self-organization via a spontaneous vertical delamination onto the ITO surface were investigated by charge transfer state, optical modelling based on transfer matrix formalism, surface energy measurement, scanning Kelvin probe force microscopy and impedance spectroscopy analysis in conjunction with atomic force microscopy and scanning electron microscopy. The relaxed charge transfer state demonstrates that PFN doping has a negligible impact on the donor: acceptor heterojunction interface. The optical simulation of device structures indicates that doping PFN into a BHJ has nearly no influence on the photon absorption profile of the active layer. Very encouraging device performance was achieved in the one-step coating PFN: BHJ PSC with ITO as the cathode, which is comparable to that of the two-step coating PSC. Moreover, for ITO-free inverted PSCs with PEDOT:PSS as the incident light top-electrode, decent device performance can also be obtained, demonstrating the remarkable universality through this facile strategy.
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| 2. |
- Gao, Feng, et al.
(författare)
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The Effect of Processing Additives on Energetic Disorder in Highly Efficient Organic Photovoltaics : A Case Study on PBDTTT-C-T:PC71BM
- 2015
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Ingår i: Advanced Materials. - : Wiley-VCH Verlag. - 0935-9648 .- 1521-4095. ; 27:26, s. 3868-3873
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Tidskriftsartikel (refereegranskat)abstract
- Energetic disorder, an important parameter affecting the performance of organic photovoltaics, is significantly decreased upon the addition of processing additives in a highly efficient benzodithiophene-based copolymer blend (PBDTTT-C-T:PC71BM). Wide-angle and small-angle X-ray scattering measurements suggest that the origin of this reduced energetic disorder is due to increased aggregation and a larger average fullerene domain size together with purer phases.
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| 3. |
- Peng, Zuosheng, et al.
(författare)
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A dual ternary system for highly efficient ITO-free inverted polymer solar cells
- 2015
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 3:36, s. 18365-18371
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Tidskriftsartikel (refereegranskat)abstract
- In this study, it has been found that a very fine nanostructure can be realized by mixing 1-chloronaphthalene (CN) - a high-boiling solvent into a binary chlorobenzene (CB) : 1,8-diiodooctane (DIO) solvent mixture to form a ternary solvent system. An improvement in energy level alignment is also obtained by doping ICBA into a binary PTB7 : PCBM[70] blend, whereby the ternary solute system provides a new pathway for charge transfer from PTB7 to the PCBM[ 70] : ICBA alloy. This is confirmed by imaging the surface morphology of the active layer using AFM and TEM, monitoring the transient film formation process and measuring the charge transfer states with Fourier transform photocurrent spectroscopy. An encouraging PCE of 7.65% is achieved from the dual ternary system, which is the highest value ever reported for an ITO-free inverted polymer solar cell with a PEDOT:PSS layer as the top semitransparent electrode - a system which is compatible with low-cost large-area roll-to-roll manufacturing.
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| 4. |
- Tao, Qiang, 1987, et al.
(författare)
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D-A(1)-D-A(2) Copolymers with Extended Donor Segments for Efficient Polymer Solar Cells
- 2015
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 1520-5835 .- 0024-9297. ; 48:4, s. 1009-1016
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Tidskriftsartikel (refereegranskat)abstract
- Typically a donor-acceptor (D-A) design strategy is used for engineering the bandgap of polymers for solar cells. However, in this work, a series of alternating D-A(1-)D-A(2) copolymers PnTQTI(F) were synthesized and characterized with oligothiophenes (nT, n = 1, 2, 3) as the donor and two electron-deficient moieties, quinoxaline and isoindigo, as the acceptors in the repeating unit. We have studied the influence of the donor segments with different numbers of thiophene units and the effect of the addition of fluorine to the quinoxaline unit of the D-A(1)-D-A(2) polymers. The photophysical, electrochemical, and photovoltaic properties of the polymers were examined via a range of techniques and related to theoretical simulations. On increasing the length of the donor thiophene units, broader absorption spectra were observed in addition to a sequential increase in HOMO levels, while the LUMO levels displayed very small variations. The addition of fluorine to the quinoxaline unit not only decreased the HOMO levels of the resulting polymers but also enhanced the absorption coefficients. A superior photovoltaic performance was observed for the P3TQTI-F-based device with a power conversion efficiency (PCE) of 7.0%, which is the highest efficiency for alternating D-A(1)-D-A(2) polymers reported to date. The structureproperty correlations of the PnTQTI(F) polymers demonstrate that varying of the length of the donor segments is a valuable method for designing high-performance D-A(1)-D-A(2) copolymers and highlight the promising nature of D-A(1)-D-A(2) copolymers for efficient bulk-heterojunction solar cells.
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