The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Jean Roncali - One of the best experts on this subject based on the ideXlab platform.
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beyond efficiency scalability of molecular Donor Materials for organic photovoltaics
Journal of Materials Chemistry C, 2016Co-Authors: Jean RoncaliAbstract:The preparation of various molecules taken as representative examples of some of the main classes of molecular Donors for organic solar cells has been analyzed in order to assess the complexity and possible scaling-up of their synthesis. Several parameters are taken into account to evaluate the synthetic complexity index (SC), namely, the number of synthetic steps, the reciprocal yield of each step, the number of operations (in particular column chromatographies) required for the purification and the safety characteristics of the used chemicals. As could be intuitively understood, large complex molecular structures that have led to the highest conversion efficiencies reported so far require more complex lengthy syntheses than smaller systems. These data underline the necessity to define working molecular structures that represent an acceptable trade-off between conversion efficiency, scalability and cost in order to design active photovoltaic molecular Materials for possible large-scale production.
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Solution-processable thienoisoindigo-based molecular Donors for organic solar cells with high open-circuit voltage
Dyes and Pigments, 2015Co-Authors: Oleh Vybornyi, Jean Roncali, Philippe Blanchard, Yue Jiang, François Baert, Dora Demeter, Clément CabanetosAbstract:Two acetylene-bridged Donor–Acceptor–Donor (D-A-D) type small pi-conjugated molecules involving triphenylamine or N-phenylcarbazole as Donor blocks (D) and thienoisoindigo as the acceptor unit (A) were synthesized and characterized by UV–Vis absorption and cyclic voltammetry. These Donor Materials were mixed with [6,6]-phenyl-C61-butyric acid methyl ester to prepare bulk heterojunction solar cells by simple solution processing. Due to their low-lying highest occupied molecular orbital energy levels, high open-circuit voltages up to 0.99 V were measured. The triphenylamine end-capped derivative led to the best power conversion efficiency of ca 2.20%, which ranks among the highest reported value for thienoisoindigo-based Materials.
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structural modulation of internal charge transfer in small molecular Donors for organic solar cells
ChemInform, 2012Co-Authors: Antoine Leliege, Charleshenri Le Regent, Magali Allain, Philippe Blanchard, Jean RoncaliAbstract:The covalent bridging of the cyanovinyl thiophene acceptor group by a phenyl ring allows the modulation of internal charge transfer and LUMO energy level of Donor Materials based on small Donor-acceptor molecules.
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BODIPY derivatives as Donor Materials for bulk heterojunction solar cells
Chemical Communications, 2009Co-Authors: Theodulf Rousseau, Antonio Cravino, Thomas Bura, Gilles Ulrich, Raymond Ziessel, Jean RoncaliAbstract:BODIPY derivatives have been used as Donor in solution-processed bulk heterojunction solar cells using PCBM as acceptor. A power conversion efficiency of 1.34% has been obtained under simulated solar irradiation.
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triphenylamine thienylenevinylene hybrid systems with internal charge transfer as Donor Materials for heterojunction solar cells
Journal of the American Chemical Society, 2006Co-Authors: Sophie Roquet, Antonio Cravino, Philippe Leriche, Olivier Aleveque, Pierre Frere, Jean RoncaliAbstract:Star-shaped molecules based on a triphenylamine core derivatized with various combinations of thienylenevinylene conjugated branches and electron-withdrawing indanedione or dicyanovinyl groups have been synthesized. UV−vis absorption and fluorescence emission data show that the introduction of the electron-acceptor groups induces an intramolecular charge transfer that results in a shift of the absorption onset toward longer wavelengths and a quenching of photoluminescence. Cyclic voltammetry shows that all compounds present a reversible first oxidation process whose potential increases with the number of electron-withdrawing groups in the structure. Prototype bulk and bilayer heterojunction solar cells have been realized using fullerene C60 derivatives as acceptor material. The results obtained with both kinds of devices show that the introduction of electron-acceptor groups in the Donor structure induces an extension of the photoresponse in the visible spectral region, an increase of the maximum external...
Wai-yeung Wong - One of the best experts on this subject based on the ideXlab platform.
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synthesis characterization photophysical and photovoltaic properties of new Donor acceptor platinum ii acetylide complexes
Journal of Organometallic Chemistry, 2016Co-Authors: Qian Liu, Nianyong Zhu, Waisum Lau, Zhiyuan Xie, Lixiang Wang, Wai-yeung WongAbstract:Abstract Six new solution processable platinum(II) acetylide Donor-acceptor (D-A) triads end-capped by 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTBT) have been synthesized and characterized by photophysical and electrochemical methods. All these Materials possess low bandgaps and strong UV/Vis absorption between 400 and 700 nm. Bulk heterojunction (BHJ) solar cells based on these molecules as Donor Materials were fabricated. The best power conversion efficiency (PCE) of 1.46% with the open-circuit voltage (Voc) of 0.70 V, short-circuit current density (Jsc) of 6.17 mA cm−2 and fill factor (FF) of 0.33 was achieved under illumination of an AM 1.5 solar cell simulator. These results suggest the potential use of solution-processable small molecular platinum(II)-acetylides for efficient generation in organic photovoltaic implementation.
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high performance polymer solar cells based on a 2d conjugated polymer with an alkylthio side chain
Energy and Environmental Science, 2016Co-Authors: Zhicai He, Yongfang Li, Xiao Cheng, Yue Wu, Hongbin Wu, Wai-yeung WongAbstract:Two new two-dimension (2D)-conjugated copolymers (PBDTT-S-TT-CF and PBDTT-O-TT-CF) were designed and synthesized for the application as Donor Materials in polymer solar cells (PSCs) and for further investigation of the effect of alkylthio side chains on the photovoltaic performance of 2D-conjugated polymers. The two copolymers were prepared by the copolymerization of alkylthio- or alkoxy-thienyl-benzodithiophene (BDTT-S or BDTT-O) and thienothiophene with carbonyl and fluorine substituents (TT-CF), and they demonstrated strong and broad absorption spectra in the wavelength region from 450 nm to ca. 800 nm. The HOMO energy level of PBDTT-S-TT-CF was further down-shifted to −5.44 eV by alkylthio substitution on thiophene conjugated side chain of BDT unit and the carbonyl and fluorine substitution on TT unit. The inverted-structured PSCs based on PBDTT-S-TT-CF:PC70BM exhibited a high PCE of 9.58% with a remarkably high Voc of 0.89 V and a high FF of 71.0%. The PCE of the PSCs based on PBDTT-O-TT-CF also reached a high value of 8.68% with a Voc = 0.78 V and a higher Jsc = 16.5 mA cm−2, which is benefited from the broad absorption of PBDTT-O-TT-CF. The results further confirm the unique advantages of the alkylthio side chain in the design of state-of-the-art polymer Donor Materials for high performance PSCs with high Voc.
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effects of alkylthio and alkoxy side chains in polymer Donor Materials for organic solar cells
Macromolecular Rapid Communications, 2016Co-Authors: Chaohua Cui, Wai-yeung WongAbstract:Side chains play a considerable role not only in improving the solubility of polymers for solution-processed device fabrication, but also in affecting the molecular packing, electron affinity and thus the device performance. In particular, electron-donating side chains show unique properties when employed to tune the electronic character of conjugated polymers in many cases. Therefore, rational electron-donating side chain engineering can improve the photovoltaic properties of the resulting polymer Donors to some extent. Here, a survey of some representative examples which use electron-donating alkylthio and alkoxy side chains in conjugated organic polymers for polymer solar cell applications will be presented. It is envisioned that an analysis of the effect of such electron-donating side chains in polymer Donors would contribute to a better understanding of this kind of side chain behavior in solution-processed conjugated organic polymers for polymer solar cells.
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organic Donor Materials based on bis arylene ethynylene s for bulk heterojunction organic solar cells with high v oc values
Chemistry-an Asian Journal, 2015Co-Authors: Wai-yeung Wong, Qian Liu, Zhiyuan Xie, Hongmei Zhan, Fengrong Dai, Li ZhaoAbstract:A series of purely organic small molecules 1-4 based on bis(arylene ethynylene)s with various electron-rich aromatic bridges, such as benzene, cyclopentadithiophene (CDT), and diphenyl(p-tolyl)amine, were synthesized by a Sonogashira coupling reaction. Their optical, electronic, and electrochemical properties were fully characterized. The photovoltaic properties of these molecules as Donor Materials and [6,6]-phenyl-C71 -butyric acid methyl ester as an acceptor material in solution-processed bulk heterojunction devices were studied. Among them, CDT-bridged molecule 2 exhibited the best photovoltaic performance and achieved a power conversion efficiency of 3.28 %. In addition, the photovoltaic efficiencies of these molecules are higher than their corresponding platinum-containing counterparts, probably owing to their stronger light absorption and improved open-circuit voltage.
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improvement of open circuit voltage and photovoltaic properties of 2d conjugated polymers by alkylthio substitution
Energy and Environmental Science, 2014Co-Authors: Chaohua Cui, Wai-yeung WongAbstract:Low bandgap and two-dimensional (2D)-conjugated copolymers based on benzo[1,2-b:4,5-b′]dithiophene with conjugated thiophene side chains (BDTT) and thieno[3,4-b]thiophene with electron-withdrawing substituents (TT) are attractive high efficiency polymer Donor Materials in polymer solar cells (PSCs). In this work, we introduced an alkylthio substituent on the thiophene side chain in the polymer and synthesized a new low bandgap 2D-conjugated polymer PBDTT-S-TT. The alkylthio substituent increased the hole mobility of the polymer to 4.08 × 10−3 cm2 V−1 s−1 and down-shifted the HOMO energy level of the polymer by 0.11 eV with absorption of the polymer film red-shifted slightly. The PSCs based on PBDTT-S-TT as a Donor and [6,6]-phenyl-C71-butyric acid methyl ester (PC70BM) as an acceptor without solvent additive treatment demonstrated a high open-circuit voltage (Voc) of 0.84 V, leading to a high power conversion efficiency (PCE) of 8.42%, under the illumination of AM 1.5 G 100 mW cm−2. For comparison, the Voc and PCE of the devices based on the corresponding parent polymer PBDTT-TT with the device optimization of 3% DIO additive treatment are 0.77 V and 7.38%, respectively. The enhanced Voc value of 0.84 V for the PSC based on PBDTT-S-TT should be benefited from the down-shifted HOMO energy level of the polymer. The results indicate that the alkylthio substitution is an effective way to further improve the photovoltaic performance of the 2D-conjugated polymer Donor Materials in PSCs.
Chaohua Cui - One of the best experts on this subject based on the ideXlab platform.
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high performance conjugated polymer Donor Materials for polymer solar cells with narrow bandgap nonfullerene acceptors
Energy and Environmental Science, 2019Co-Authors: Chaohua CuiAbstract:In the past few years, the emergence of nonfullerene (n-type organic semiconductor (n-OS)) acceptors combining with the rational design of conjugated polymer Donor Materials has dominated the rapid development of highly efficient polymer solar cells (PSCs). Relative to the traditional fullerene derivative acceptors, narrow bandgap n-OS acceptors with a fused ring core possess the advantages of strong absorption in the visible-near infrared region and tunable electronic energy levels. On the other hand, the anisotropic conjugated structures of n-OS acceptors make it more challenging to match them with conjugated polymer Donors. Therefore, it is critical to rationally design conjugated polymer Donors with complementary absorption and matching electronic energy levels with nonfullerene acceptors for realizing high performance PSCs. Here we review the recent development of state-of-the-art wide-bandgap conjugated polymer Donor Materials, including D–A copolymers with BDT (benzodithiophene) as the D-unit and BDD (1,3-bis(thiophen-2-yl)-5,7-bis(2-ethylhexyl)benzo[1,2-c:4,5-c′]dithiophene-4,8-dione), FBTA (fluorinated benzotriazole) or quinoxaline as the A-unit, etc., for efficient PSCs based on narrow bandgap n-OS acceptors. Our focus is mainly on the design strategies, chemical structure–property relationships, and photovoltaic performance of the polymer Donors. We hope that this review article could contribute to better understanding of the design strategies of high-performance conjugated polymer Donors for nonfullerene PSCs.
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the effect of alkylthio side chains in oligothiophene based Donor Materials for organic solar cells
Molecular Systems Design & Engineering, 2018Co-Authors: Yan Zou, Hang Yang, Yingying Dong, Chaohua CuiAbstract:With respect to the molecular system of Donor Materials for organic solar cells (OSCs), the π-conjugated backbone is the most important component in determining their OSC-related physicochemical properties. On the other hand, selecting side chains is essential in designing photovoltaic Materials, since side chains (especially alkylthio side chains) have a considerable effect, not only on enabling the solubility of Materials for solution-processed device fabrication, but also on physicochemical properties, molecular packing and thus the OSC device performance. In this work, we introduce alkylthio side-chains in the molecular π-conjugated backbone to develop a new oligothiophene-based Donor material (namely BDT-S-TRS) for OSCs. The theoretical calculations and molecular simulation with density functional theory (DFT) and cyclic voltammetry results reveal that BDTT-S-TRS showed a lower HOMO energy level than its alkyl side-chain counterpart. Especially, BDTTT-S-TRS has a linear backbone with better planarity. The OSC device based on BDT-S-TRS exhibited a power conversion efficiency (PCE) of 8.07%, with a notable fill factor (FF) of 0.705.
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evaluation of electron Donor Materials for solution processed organic solar cells via a novel figure of merit
Advanced Energy Materials, 2017Co-Authors: Jie Min, Chaohua Cui, Yongsheng Chen, Xiangjian Wan, Bin Kan, Yuriy N Luponosov, Haiwei Chen, S A Ponomarenko, Christoph J BrabecAbstract:Organic photovoltaic (OPV) technology offers many advantages, although no commercial applications have been achieved after more than a decade of intensive research and development. Several challenges have yet to be overcome including high power conversion efficiency (PCE), good processability, low cost, and excellent long-term stability, and so on. In this article, these fundamental challenges are significantly addressed by surveying and analyzing a new merit factor for material applied accessibility containing three parameters: synthetic complexity, device efficiency, and photostability. Thirty-five Donor small molecules are introduced to assess their synthetic accessibility. Furthermore, the PCEs and device photostability of these molecules are carried out, and further measured under one sun illumination within 200 h, respectively. Combining with the characteristics of these three factors, investigated molecules are ranked according to an industrial figure of merit (i-FOM), while some guidelines for the material design and synthesis are given. It is suggested that a PCE of >14% and an i-FOM of >20% via active material engineering are realistic for possible industry future of OPV. Along with the systematic study, it is believed that this i-FOM can be taken into consideration at an early stage of molecular design and provides valuable insight for efficient evaluation of photovoltaic Materials for possible commercial applications.
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manipulating the photovoltaic properties of small molecule Donor Materials by tailoring end capped alkylthio substitution
RSC Advances, 2016Co-Authors: Xiao Cheng, Chaohua CuiAbstract:The engineering of alkylthio side chains is a smart and effective strategy to improve the photovoltaic properties of Donor Materials for organic solar cells (OSCs). In order to further exploit the capability of alkylthio chains in tuning the physicochemical and photovoltaic properties of small-molecule Donor Materials, two small molecules DTS-BTT-S and BDTT-BTT-S with alkylthio end groups were designed and synthesized. The DFT calculation results reveal that introducing alkylthio end groups in DTS-BTT-S and BDTT-BTT-S effectively down-shifted the HOMO energy levels in comparison with their analogous molecules with alkyl end groups. The DTS-BTT-S based OSC device exhibited a higher Voc of 0.840 V, with a PCE of 3.65% without the need of extra-treatments of the active layer. The optimized device based on BDTT-BTT-S showed a higher PCE of 5.21%, with Voc = 0.823 V, Jsc = 10.93 mA cm−2 and FF = 57.2%.
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effects of alkylthio and alkoxy side chains in polymer Donor Materials for organic solar cells
Macromolecular Rapid Communications, 2016Co-Authors: Chaohua Cui, Wai-yeung WongAbstract:Side chains play a considerable role not only in improving the solubility of polymers for solution-processed device fabrication, but also in affecting the molecular packing, electron affinity and thus the device performance. In particular, electron-donating side chains show unique properties when employed to tune the electronic character of conjugated polymers in many cases. Therefore, rational electron-donating side chain engineering can improve the photovoltaic properties of the resulting polymer Donors to some extent. Here, a survey of some representative examples which use electron-donating alkylthio and alkoxy side chains in conjugated organic polymers for polymer solar cell applications will be presented. It is envisioned that an analysis of the effect of such electron-donating side chains in polymer Donors would contribute to a better understanding of this kind of side chain behavior in solution-processed conjugated organic polymers for polymer solar cells.
Peter Bauerle - One of the best experts on this subject based on the ideXlab platform.
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a d a type s n heteropentacenes next generation molecular Donor Materials for efficient vacuum processed organic solar cells
Advanced Materials, 2014Co-Authors: Amaresh Mishra, Dusko Popovic, Astrid Vogt, Hannelore Kast, Tanja D Leitner, Karsten Walzer, Martin Pfeiffer, Elena Menaosteritz, Peter BauerleAbstract:A new class of acceptor-substituted S,N-heteropentacenes is developed for vacuum-processed organic solar cells, providing encouraging power conversion efficiencies of up to 6.5%. Atomic force microscopy (AFM) investigations give a direct correlation between the blend film morphology and the photovoltaic parameters, such as short-circuit current density (JSC ) and fill factor (FF).
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dicyanovinylene substituted selenophene thiophene co oligomers for small molecule organic solar cells
Chemistry of Materials, 2011Co-Authors: Stefan Haid, Amaresh Mishra, Martin Pfeiffer, Christian Uhrich, Peter BauerleAbstract:We report on the design, synthesis, and characterization of a series of terminal dicyanovinylene-substituted quinquechalcogenophenes as light-harvesting small-molecule Donor Materials for organic solar cells. The spectroscopic, electrochemical, and thermal properties of these pentamers were investigated. The replacement of thiophene unit(s) by selenophene(s) results in a bathochromic shift of the longest wavelength absorption band with concomitant increase of the molar extinction coefficient. Cyclic voltammetry measurements revealed fully reversible oxidation and irreversible reduction processes. The highest occupied and lowest unoccupied molecular orbital (HOMO/LUMO) energy levels were determined from electrochemical measurements and lie in the range of −5.6 and −3.8 eV. Vacuum-deposited bulk-heterojunction solar cells fabricated with the novel chalcogenophenes as Donor and C60 as acceptor displayed high open-circuit voltages of up to 1 V, short-circuit currents close to 8 mA·cm–2, and power conversion e...
Christoph J Brabec - One of the best experts on this subject based on the ideXlab platform.
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evaluation of electron Donor Materials for solution processed organic solar cells via a novel figure of merit
Advanced Energy Materials, 2017Co-Authors: Jie Min, Chaohua Cui, Yongsheng Chen, Xiangjian Wan, Bin Kan, Yuriy N Luponosov, Haiwei Chen, S A Ponomarenko, Christoph J BrabecAbstract:Organic photovoltaic (OPV) technology offers many advantages, although no commercial applications have been achieved after more than a decade of intensive research and development. Several challenges have yet to be overcome including high power conversion efficiency (PCE), good processability, low cost, and excellent long-term stability, and so on. In this article, these fundamental challenges are significantly addressed by surveying and analyzing a new merit factor for material applied accessibility containing three parameters: synthetic complexity, device efficiency, and photostability. Thirty-five Donor small molecules are introduced to assess their synthetic accessibility. Furthermore, the PCEs and device photostability of these molecules are carried out, and further measured under one sun illumination within 200 h, respectively. Combining with the characteristics of these three factors, investigated molecules are ranked according to an industrial figure of merit (i-FOM), while some guidelines for the material design and synthesis are given. It is suggested that a PCE of >14% and an i-FOM of >20% via active material engineering are realistic for possible industry future of OPV. Along with the systematic study, it is believed that this i-FOM can be taken into consideration at an early stage of molecular design and provides valuable insight for efficient evaluation of photovoltaic Materials for possible commercial applications.
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towards 15 energy conversion efficiency a systematic study of the solution processed organic tandem solar cells based on commercially available Materials
Energy and Environmental Science, 2013Co-Authors: Derya Baran, Karen Forberich, Florian Machui, Tayebeh Ameri, Mathieu Turbiez, Miguel Carrascoorozco, Martin Drees, Antonio Facchetti, Frederik C Krebs, Christoph J BrabecAbstract:Owing to the lack of scalable high performance Donor Materials, studies on mass-produced organic photovoltaic (OPV) devices lag far behind that on lab-scale devices. In this work, we choose 6 already commercially available conjugated polymers and systematically investigate their potential in organic tandem solar cells. All the devices are processed under environmental conditions using doctor-blading, which is highly compatible with mass-production coating technologies. Power conversion efficiencies (PCE) of 6–7% are obtained for OPV devices based on different active layers. Optical simulations based on experimental data are performed for all realized tandem solar cells. An efficiency potential of ∼10% is estimated for these compounds in combination with phenyl-C61-butyric acid methyl ester (PCBM) as an acceptor. In addition, we assume a hypothetical, optimized acceptor to understand the limitation of Donors. It is suggested that a PCE of >14% is realistic for tandem solar cells based on these commercially available Donor Materials. Along with the demonstration of novel intermediate layers we believe that this systematic study provides valuable insight for those attempting to realize the high efficiency potential of tandem architectures.