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1.
Felix Deschler Antonietta De Sio Elizabeth von Hauff Peter Kutka Tobias Sauermann Hans‐J. Egelhaaf Jens Hauch Enrico Da Como 《Advanced functional materials》2012,22(7):1461-1469
A study of how light‐induced degradation influences the fundamental photophysical processes in the active layer of poly(3‐hexylthiophene)/[6,6]‐phenyl C61‐butyric acid methyl ester (P3HT/PCBM) solar cells is presented. Non‐encapsulated samples are systematically aged by exposure to AM 1.5 illumination in the presence of dry air for different periods of time. The extent of degradation is quantified by the relative loss in the absorption maximum of the P3HT, which is varied in the range 0% to 20%. For degraded samples an increasing loss in the number of excitons within the P3HT domains is observed with longer ageing periods. This loss occurs rapidly, within the first 15 ps after photoexcitation. A more pronounced decrease in the population of polarons than excitons is observed, which also occurs on a timescale of a few picoseconds. These observations, complemented by a quantitative analysis of the polaron and exciton population dynamics, unravel two primary loss mechanisms for the performances of aged P3HT/PCBM solar cells. One is an initial ultrafast decrease in the polaron generation, apparently not related to the exciton diffusion to the polymer/fullerene interface; the second, less significant, is a loss in the exciton population within the photoexcited P3HT domains. The steady‐state photoinduced absorption spectra of degraded samples exhibits the appearance of a signal ascribed to triplet excitons, which is absent for non‐degraded samples. This latter observation is interpreted considering the formation of degraded sites where intersystem crossing and triplet exciton formation is more effective. The photovoltaic characteristics of same blends are also studied and discussed by comparing the decrease in the overall power conversion efficiency of solar cells. 相似文献
2.
Apparent recombination orders exceeding the value of two expected for bimolecular recombination have been reported for organic solar cells in various publications. Two prominent explanations are bimolecular losses with a carrier concentration dependent prefactor due to a trapping limited mobility and protection of trapped charge carriers from recombination by a donor–acceptor phase separation until re‐emission from these deep states. In order to clarify which mechanism is dominant temperature‐ and illumination‐dependent charge extraction measurements are performed under open circuit and short circuit conditions at poly(3‐hexylthiophene‐2,5‐diyl):[6,6]‐phenyl‐C61 butyric acid methyl ester (P3HT:PC61BM) and PTB7:PC71BM (poly[[4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl][3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thiophenediyl]]) solar cells in combination with current–voltage characteristics. It is shown that the charge carrier density n dependence of the mobility μ and the recombination prefactor are different for P3HT:PC61BM at temperatures below 300 K and PTB7:PC71BM at room temperature. Therefore, in addition to μ(n), a detrapping limited recombination in systems with at least partial donor–acceptor phase separation is required to explain the high recombination orders. 相似文献
3.
Xin Li Huizhen Ke Sunsun Li Mengyuan Gao Saimeng Li Jinfeng Yu Haijuan Xie Kangkang Zhou Kai Zhang Long Ye 《Advanced functional materials》2024,34(29):2400702
Intrinsically stretchable organic photovoltaic cells (OPVs) have garnered significant attention as crucial devices for powering next-generation wearable electronics. Despite the rapid power conversion efficiency gains in champion OPVs, their brittle stretchability has failed to meet the demands of the Internet of Things era, severely hindering further development and practical applications. In this regard, a new dual-donor polymer blending strategy is demonstrated for constructing intrinsically stretchable OPVs by designing a novel high-molecular–weight conjugated polymer PM6-HD. This PM6 derivative featuring long alkyl chains can reach a sufficiently high molecular weight and thus exhibits a high fracture strain exceeding 90%, which is ≈12 times higher than the benchmark PM6. Synergistic optimization of mechanical properties and photovoltaic performance in polymer:small molecule and all-polymer systems constructed from the physical blends of PM6 and PM6-HD is achieved. Crucially, the resulting intrinsically stretchable OPV demonstrates excellent stretchability and stability, with a record PCE80% strain of 50.3% and the efficiency retention of above 80% even after 1000 cycles of cyclic stretching at high strains. This work contributes to the advancement of intrinsically stretchable OPV technology and opens up new possibilities for its integration into wearable electronic devices. 相似文献
4.
Organic Photovoltaics: Photovoltaic Function and Exciton/Charge Transfer Dynamics in a Highly Efficient Semiconducting Copolymer (Adv. Funct. Mater. 1/2014)
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Jodi M. Szarko Brian S. Rolczynski Sylvia J. Lou Tao Xu Joseph Strzalka Tobin J. Marks Luping Yu Lin X. Chen 《Advanced functional materials》2014,24(1):2-2
5.
Pavel A. Troshin Diana K. Susarova Yury L. Moskvin Ilya E. Kuznetsov Sergei A. Ponomarenko Ekaterina N. Myshkovskaya Ksenya A. Zakharcheva Alexander A. Balakai Sergei D. Babenko Vladimir F. Razumov 《Advanced functional materials》2010,20(24):4351-4357
The problem of batch‐to‐batch variation of electronic properties and purity of conjugated polymers used as electron donor and photon harvesting materials in organic solar cells is addressed. A simple method is developed for rapid analysis of electronic quality of polymer‐based materials. It is shown that appearance of impurities capable of charge trapping changes electrophysical properties of conjugated polymers. In particular, a clear correlation between the effective relaxation time τeff and relative photovoltaic performance (η/ηmax) is revealed for samples of poly(3‐hexylthiophene) intentionally polluted with a palladium catalyst. This dependence is also valid for all other investigated samples of conjugated polymers. Therefore, fast impedance measurements at three different frequencies allow one to draw conclusions about the purity of the analyzed polymer sample and even estimate its photovoltaic performance. The developed method might find extensive applications as a simple tool for product quality control in the laboratory and industrial‐scale production of conjugated polymers for electronic applications. 相似文献
6.
Martijn Lenes Mauro Morana Christoph J. Brabec Paul W. M. Blom 《Advanced functional materials》2009,19(7):1106-1111
The charge transport and photogeneration in solar cells based on the low bandgap‐conjugated polymer, poly[2,6‐(4,4‐bis‐(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b; 3,4‐b′]dithiophene)‐alt‐4,7‐(2,1,3‐benzothiadiazole)] (PCPDTBT) and fullerenes is studied. The efficiency of the solar cells is limited by a relatively low fill factor, which contradicts the observed good and balanced charge transport in these blends. Intensity dependent measurements display a recombination limited photocurrent, characterized by a square root dependence on effective applied voltage, a linear dependence on light intensity and a constant saturation voltage. Numerical simulations show that the origin of the recombination limited photocurrent stems from the short lifetime of the bound electron‐hole pairs at the donor/acceptor interface. 相似文献
7.
Jodi M. Szarko Brian S. Rolczynski Sylvia J. Lou Tao Xu Joseph Strzalka Tobin J. Marks Luping Yu Lin X. Chen 《Advanced functional materials》2014,24(1):10-26
Exciton dissociation is a key step for the light energy conversion to electricity in organic photovoltaic (OPV) devices. Here, excitonic dissociation pathways in the high‐performance, low bandgap “in‐chain donor–acceptor” polymer PTB7 by transient optical absorption (TA) spectroscopy in solutions, neat films, and bulk heterojunction (BHJ) PTB7:PC71BM (phenyl‐C71‐butyric acid methyl ester) films are investigated. The dynamics and energetics of the exciton and intra‐/intermolecular charge separated states are characterized. A distinct, dynamic, spectral red‐shift of the polymer cation is observed in the BHJ films in TA spectra following electron transfer from the polymer to PC71BM, which can be attributed to the time evolution of the hole–electron spatial separation after exciton splitting. Effects of film morphology are also investigated and compared to those of conjugated homopolymers. The enhanced charge separation along the PTB7 alternating donor–acceptor backbone is understood by intramolecular charge separation through polarized, delocalized excitons that lower the exciton binding energy. Consequently, ultrafast charge separation and transport along these polymer backbones reduce carrier recombination in these largely amorphous films. This charge separation mechanism explains why higher degrees of PCBM intercalation within BHJ matrices enhances exciton splitting and charge transport, and thus increase OPV performance. This study proposes new guidelines for OPV materials development. 相似文献
8.
Yongxi Li Kai Yao Hin‐Lap Yip Fei‐Zhi Ding Yun‐Xiang Xu Xiaosong Li Yu Chen Alex K.‐Y. Jen 《Advanced functional materials》2014,24(23):3631-3638
A multi‐ring, ladder‐type low band‐gap polymer (PIDTCPDT‐DFBT) is developed to show enhanced light harvesting, charge transport, and photovoltaic performance. It possesses excellent planarity and enhanced effective conjugation length compared to the previously reported fused‐ring polymers. In order to understand the effect of extended fused‐ring on the electronic and optical properties of this polymer, a partially fused polymer PIDTT‐T‐DFBT is also synthesized for comparison. The fully rigidified polymer provides lower reorganizational energy, resulting in one order higher hole mobility than the reference polymer. The device made from PIDTCPDT‐DFBT also shows a quite promising power conversion efficiency of 6.46%. Its short‐circuit current (14.59 mA cm?2) is also among the highest reported for ladder‐type polymers. These results show that extending conjugation length in fused‐ring ladder polymers is an effective way to reduce band‐gap and improve charge transport for efficient photovoltaic devices. 相似文献
9.
Chen Kong Byeongseop Song Emily A. Mueller Jinsang Kim Anne J. McNeil 《Advanced functional materials》2019,29(26)
Recent advances have led to conjugated polymer‐based photovoltaic devices with efficiencies rivaling amorphous silicon. Nevertheless, these devices become less efficient over time due to changes in active layer morphology, thereby hindering their commercialization. Copolymer additives are a promising approach toward stabilizing blend morphologies; however, little is known about the impact of copolymer sequence, composition, and concentration. Herein, the impact of these parameters is determined by synthesizing random, block, and gradient copolymers with a poly(3‐hexylthiophene) (P3HT) backbone and side‐chain fullerenes (phenyl‐C61‐butyric acid methyl ester (PC61BM)). These copolymers are evaluated as compatibilizers in photovoltaic devices with P3HT:PC61BM as the active layer. The random copolymer with 20 mol% fullerene side chains and at 8 wt% concentration in the blend gives the most stable morphologies. Devices containing the random copolymer also exhibit higher and more stable power conversion efficiencies than the control device. Combined, these studies point to the random copolymer as a promising new scaffold for stabilizing bulk heterojunction photovoltaics. 相似文献
10.
Andrew J. Pearson Tao Wang Alan D. F. Dunbar Hunan Yi Darren C. Watters David M. Coles Paul A. Staniec Ahmed Iraqi Richard A. L. Jones David G. Lidzey 《Advanced functional materials》2014,24(5):659-667
The evolution of film structure is reported during solution casting of PCDTBT:PC70BM 1:4 wt%, a polymer:fullerene blend system that finds application in an organic photovoltaic device. Using the complimentary techniques of grazing‐incidence wide‐angle X‐ray scattering and spectroscopic ellipsometry, a number of distinct processes that occur during film formation are identified. This includes the growth of fullerene molecules into nanoscale aggregates, the onset of which coincides with the solubility limit of the material in the casting solvent being reached. An apparent delay in Bragg scatter from the PCDTBT‐rich phase of the film suggests that, for the film composition studied here, the aggregation of PC70BM precedes weak self‐organisation of the conjugated polymer. This behaviour is compared with the drying dynamics of a number of different polymer:fullerene blends that each contain a high weight fraction of fullerene molecules, and a range of comparable solid concentrations are identified beyond which the precipitation of fullerene aggregates from solution occurs. These observations provide an insight into the development of structure in relatively amorphous polymer:fullerene blends for organic photovoltaic applications and potentially assists the future optimisation of this category of materials. 相似文献
11.
Suchol Savagatrup Aditya S. Makaram Daniel J. Burke Darren J. Lipomi 《Advanced functional materials》2014,24(8):1169-1181
Despite the importance of mechanical compliance in most applications of semiconducting polymers, the effects of structural parameters of these materials on their mechanical properties are typically not emphasized. This paper examines the effect of length of the pendant group on the tensile modulus and brittleness for a series of regioregular poly(3‐alkylthiophenes) (P3ATs) and their blends with a soluble fullerene derivative, PCBM. The tensile modulus decreases with increasing length of the alkyl side‐chain, from 1.87 GPa for butyl side chains to 0.16 GPa for dodecyl chains. The moduli of P3AT:PCBM blends films are greater than those of the pure polymers by factors of 2–4. A theoretical model produces a trend in the effect of alkyl side chain on tensile modulus that follows closely to the experimental measurements. Tensile modulus correlates with brittleness, as the strain at which cracks appear is 6% for P3BT and >60% for P3OT. Adhesion of the P3AT film to a polydimethylsiloxane (PDMS) substrate is believed to play a role in an apparent increase in brittleness from P3OT to P3DDT. The additive 1,8‐Diiodooctane (DIO) reduces the modulus of P3HT:PCBM blend by a factor of 3. These results could enable mechanically robust, flexible, and stretchable electronics. 相似文献
12.
Jiajun Peng Xiaoqing Chen Yani Chen Oskar J. Sandberg Ronald
sterbacka Ziqi Liang 《Advanced Electronic Materials》2016,2(3)
We have utilized the metal–insulator–semiconductor charge extraction by linearly increasing voltage (MIS‐CELIV) technique to clarify the hole‐ and electron‐transport properties in benchmark poly(3‐hexylthiophene) (P3HT) and its blend with phenyl‐C61‐butyric acid methyl ester (PCBM) by using a thick lithium fluoride (LiF) as the charge‐blocking layer. Both dark and light MIS‐CELIV are employed to comparatively investigate the differences in the recombination process and charge mobilities in neat P3HT and P3HT:PCBM blends. Our studies quantitatively show that balanced hole and electron transport can be achieved in the P3HT:PCBM blend under light illumination, leading to a high efficiency in the photovoltaic cell. Furthermore, light MIS‐CELIV can be employed as a novel method to directly evaluate the capability of photoelectric conversion of organic photovoltaic materials. 相似文献
13.
14.
Nabankur Deb Bohao Li Maximilian Skoda Sarah Rogers Yan Sun Xiong Gong Alamgir Karim Bobby G. Sumpter David G. Bucknall 《Advanced functional materials》2016,26(12):1908-1920
Nanoscale bulk heterojunction (BHJ) systems, consisting of fullerenes dispersed in conjugated polymers have been actively studied in order to produce high performance organic photovoltaics. How the BHJ morphology affects device efficiency, is currently ill‐understood. Neutron reflection together with grazing incidence X‐ray and neutron scattering and X‐ray photoelectron spectroscopy are utilized to gain understanding of the BHJ morphology in functional devices. For nine model systems, based on mixtures of three poly(3‐alkyl thiophenes, P3AT) (A = butyl, hexyl, octyl) blended with three different fullerene derivatives, the BHJ morphology through the film thickness is determined. It is shown that fullerene enrichment occurs at both the electrode interfaces after annealing. The degree of fullerene enrichment is found to strongly correlate with the short circuit current (JSC ) and to a lesser degree with the fill factor. Based on these findings, it is demonstrated that by deliberately adding a fullerene layer at the electron transport layer interface, JSC can be increased by up to 20%, resulting in an overall increase in power conversion efficiency of 5%. 相似文献
15.
Highly thermal stable organic bulk heterojunction (OBHJ) photovoltaic cells are demonstrated with crosslinkable open‐cage fullerenes ( COF ) as additives in the active layer. Partial incorporation of COF , ≈10–15 wt% with weight ratio of P3HT: PC61BM = 1:0.9, builds up three‐dimensional local borders upon heating treatment at 150 °C for 10 min. This process induces crosslinking chemical reaction through activating the styryl moiety in COF and reduces phase aggregation rates of fullerenes materials. Supported by statistics of devices degradation data analysis and optical microscopy study, the devices with COF show longer lifetime with keeping their efficiency (t = 144 h) under accelerated heating test at 150 °C, while PCE of normal devices without COF drop dramatically. These results demonstrate that the thermally crosslinkable COF is an excellent additive for highly thermal stable and durable OPVs applications. 相似文献
16.
Nicola Beaumont Sang Wan Cho Paul Sullivan David Newby Kevin E. Smith Tim. S. Jones 《Advanced functional materials》2012,22(3):561-566
High‐efficiency fullerene‐free single‐heterojunction (SHJ) organic photovoltaic (OPV) cells consisting of tetracene (Tc) as a typical donor material and boron subphthalocyanine chloride (SubPc) as an acceptor material are reported. Cells containing SubPc as a direct replacement for C60 exhibit an ~60% improvement in open circuit voltage (Voc) achieving a maximum Voc of 1.24 V, which is amongst the highest values acheived to date for SHJ devices. This resulted in an overall improvement of ~60% in power conversion efficiency from 1.8%, for Tc/C60 cells, to 2.9% for Tc/SubPc. The OPV device results are complemented by soft X–ray photoelectron spectroscopy (PES) measurements of the interfacial energetics of both systems. The results demonstrate that SubPc shows considerable promise as an electron acceptor material for future cell designs. 相似文献
17.
Yen‐Ju Cheng Chao‐Hsiang Hsieh Pei‐Jung Li Chain‐Shu Hsu 《Advanced functional materials》2011,21(9):1723-1732
The successful design and synthesis of two styryl‐functionalized fullerene derivatives, [6,6]‐phenyl‐C61‐butyric acid styryl dendron ester (PCBSD) and [6,6]‐phenyl‐C61‐butyric acid styryl ester (PCBS) is presented. The polymerizable PCBS or PCBSD materials are incorporated into a poly(3‐hexylthiophene) (P3HT):[6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) blend to form an active layer of ternary blend. The blending systems are first thermally annealed at 110 C for 10 min to induce optimal morphology, followed by heating at 150 C for 10 min to trigger the in situ polymerization of styrene groups. Through chemical crosslinking of PCBSD, the initial morphology of the blend (P3HT:PCBM:PCBSD = 6:5:1 in weight) can be effectively fixed and stably preserved. The device based on this blend shows extremely stable device characteristics, delivering an average power conversion efficiency (PCE) of 3.7% during long‐term thermal treatment. By molecular engineering to reduce the insulating portion, PCBS with higher C60 content (71 wt%) possesses better electron‐transport properties than PCBSD (58 wt%). Encouragingly, at a low doping concentration of PCBS in the blend (P3HT:PCBM:PCBS = 6:5:1 in weight), linear‐polymerized PCBS can stabilize the morphology against thermal heating. This device exhibits more balanced charge mobility to achieve an average PCE of 3.8% over 25 h heating at 150 °C. 相似文献
18.
Naga Rajesh Tummala Shafigh Mehraeen Yao‐Tsung Fu Chad Risko Jean‐Luc Brédas 《Advanced functional materials》2013,23(46):5800-5813
The ability to detail how molecules pack in the bulk and at the various materials interfaces in the active layer of an organic solar cell is important to further understanding overall device performance. Here, [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM), a preferred electron‐acceptor material in organic solar cells, is studied through molecular dynamics (MD) simulations; the goal is to examine the effects of temperature and trace solvents on the packing and morphological features of bulk PCBM. Solubility (miscibility) parameters, melting and order‐disorder transitions, surface energies, and orientational distributions as a function of different starting configurations are discussed. On the basis of the derived morphologies, electronic structure calculations and a kinetic Monte Carlo approach are combined to evaluate the parameters impacting electron mobility in crystalline and amorphous PCBM structures. 相似文献
19.
Ajay Ram Srimath Kandada Simone Guarnera Francesco Tassone Guglielmo Lanzani Annamaria Petrozza 《Advanced functional materials》2014,24(20):3094-3099
The correlation between molecular scale morphology and charge generation across hybrid photovoltaic interfaces made of metal oxides (ZnO and TiO2) and a prototypical electron donor polymer, P3HT, is investigated. Device characterization and UV‐NIR transient absorption spectroscopy are used to demonstrate that the local disorder of the polymer chains on the surface of the metal–oxide film provides better electron injection efficiencies than the crystalline phases, though the latter are essential for energy and charge transport. An unambiguous spectroscopic tool is also demonstrated to probe the occupation of the conduction band of ZnO following the electron injection from the polymer through the ultrafast tracking of the Burstein‐Moss effect. 相似文献
20.
Michael P. Tsang Guido W. Sonnemann Dario M. Bassani 《Progress in Photovoltaics: Research and Applications》2016,24(5):645-655
A life cycle assessment case study involving organic photovoltaic technology using phenyl‐C61‐butyric acid methyl ester and poly(3‐hexylthiophene) is presented. Although solar technology converts freely available solar radiation into more useful forms of energy, potential environmental impacts can occur during the life cycle of the product. A cradle‐to‐gate life cycle assessment is completed, comparing organic solar cells with traditional silicon‐based cells across 18 multiple criteria. The functional unit is defined as the production of 1 watt‐peak of electricity produced. The inventory is based on prospective organic solar cell technology and two traditional silicon technologies. The results demonstrate that from a life cycle perspective, organic solar cells can outperform conventional silicon solar cells with impacts reduced by 93%. The energy payback time for the default organic photovoltaic cell was 0.21 years (75 days) compared with multicrystalline silicon and amorphous silicon's 2.7 and 2.2 years, respectively. The minimum required lifetime of the organic cells, so that their impacts were no worse than amorphous silicon's over 25 years, was measured between 1.2 and 8.9 years. Results of the sensitivity analysis demonstrate that consideration of manufacturing routes (e.g., fullerene or solar cell production) can be targeted using life cycle assessment for further improvements in the environmental, human health, and ecotoxicity profile of organic solar cells. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献