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1.
ChemSusChem ; 2020 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-32314499

RESUMO

In this work, we introduced the core-twisted tetrachloroperylenediimides (ClPDIs) as new efficient electron-transporting materials (ETMs) to replace the commonly used fullerene acceptor (PC 61 BM) in inverted planar perovskite solar cells (PSCs). The ClPDI shows a low-lying LUMO energy level of -3.95 eV, which is compatible to the conduction band of MAPbI 3-X Cl X (-3.90 eV). In addition, we investigated the role of the alkyl side chain length at the imide position on ClPDI in modulating the molecular solubility, aggregation capacity for charge transport properties, surface hydrophobicity and perovskite solar cell perofrmances. The device based on ClPDI-C4 (ClPDI with n-butyl side chains) as ETM achieved a maximum power conversion efficiency (PCE) of 17.3% under the standard AM 1.5G illumination, which is very competitive to the reference device employing PC 61 BM/C 60 (PCE= 17.2%) as ETM. Moreover, the devices with ClPDIs as ETMs exhibit better device stability than that with PC 61 BM/C 60 . This work highlights the great potential of ClPDI derivatives as the low cost (~2.0 USD per gram) and efficient ETMs to achieve efficient solution-processed inverted PSCs. We believe this class of ClPDI derivatives that will further promote the performance and stability of PSCs after extended investigation.

2.
ACS Appl Mater Interfaces ; 11(38): 35088-35094, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31462035

RESUMO

Hybrid lead halide perovskites continue to attract interest for use in optoelectronic devices such as solar cells and light-emitting diodes. Although challenging, the replacement of toxic lead in these systems is an active field of research. Recently, the use of trivalent metal cations (Bi3+ and Sb3+) that form defect perovskites A3B2X9 has received great attention for the development of solar cells, but their light-emissive properties have not previously been studied. Herein, an all-inorganic antimony-based two-dimensional perovskite, Cs3Sb2I9, was synthesized using the solution process. Vapor-anion-exchange method was employed to change the structural composition from Cs3Sb2I9 to Cs3Sb2Br9 or Cs3Sb2Cl9 by treating CsI/SbI3 spin-coated films with SbBr3 or SbCl3, respectively. This novel method facilitates the fabrication of Cs3Sb2Br9 or Cs3Sb2Cl9 through solution processing without the need of using poorly soluble precursors (e.g., CsCl and CsBr). We go on to demonstrate electroluminescence from a device employing Cs3Sb2I9 emitter sandwiched between ITO/PEDOT:PSS and TPBi/LiF/Al as the hole and electron injection electrodes, respectively. A visible-infrared radiance of 0.012 W·Sr-1·m-2 was measured at 6 V when Cs3Sb2I9 was the active emitter layer. These proof-of-principle devices suggest a viable path toward low-dimensional, lead-free A3B2X9 perovskite optoelectronics.

3.
Chemistry ; 25(24): 6131-6140, 2019 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-30791165

RESUMO

Versatile photoresponsive gels based on tripodal low molecular weight gelators (LMWGs) are reported. A cyclohexane-1,3,5-tricarboxamide (CTA) core provides face-to-face hydrogen bonding and a planar conformation, inducing the self-assembly of supramolecular polymers. The CTA core was substituted with three arylazopyrazole (AAP) arms. AAP is a molecular photoswitch that isomerizes reversibly under alternating UV and green light irradiation. The E isomer of AAP is planar, favoring the self-assembly, whereas the Z isomer has a twisted structure, leading to a disassembly of the supramolecular polymers. By using tailor-made molecular design of the tripodal gelator, light-responsive organogels and hydrogels were obtained. Additionally, in the case of the hydrogels, AAP was coupled to the core through hydrazones, so that the hydrogelator and, hence, the photoresponsive hydrogel could also be assembled and disassembled by using dynamic covalent chemistry.

4.
Nanoscale ; 11(6): 2892-2900, 2019 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-30688332

RESUMO

Dissolution of lithium polysulfide (LiPS) into the electrolyte during discharging, causing shuttling of LiPS from the cathode to the lithium (Li) metal, is mainly responsible for the capacity decay and short battery life of lithium-sulfur batteries (LSBs). Herein, we designed a separator comprising polypropylene (PP) coated with MoO3 nanobelts (MNBs), prepared through facile grinding of commercial MoO3 powder. The formation of Li2Sn-MoO3 during discharging inhibited the polysulfide shuttling; during charging, Li passivated LixMoO3 facilitated ionic transfer during the redox reaction by decreasing the charge transfer resistance. This dual-interaction mechanism of LiPS-with both Mo and the formation of LixMoO3-resulted in a substantially high initial discharge capacity at a very high current density of 5C, with 29.4% of the capacity retained after 5000 cycles. The simple fabrication approach and extraordinary cycle life observed when using this MNB-coated separator suggest a scalable solution for future commercialization of LSBs.

5.
ACS Appl Mater Interfaces ; 11(2): 2060-2070, 2019 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-30582792

RESUMO

Despite issues related to dendrite formation, research on Li metal anodes has resurged because of their high energy density. In this study, graphene oxide (GO) layers are decorated onto Li metal anodes through a simple process of drop-casting and spray-coating. The self-assembly of GO is exploited to synthesize coatings having compact, mesoporous, and macroporous morphologies. The abilities of the GO coatings to suppress dendrite formation are compared through Li|Li symmetrical cell charging at a current density of 5 mA cm-2 for 2000 cycles-a particularly abusive test. The macroporous structure possesses the lowest impedance, whereas the compact structure excels in terms of stability. Moreover, GO exhibits a low nucleation overpotential and is transformed into reduced GO with enhanced conductivity during the operation of the cells; both factors synergistically mitigate the issue of dendrite formation. Li-S batteries incorporating the GO-decorated Li anodes exhibit an initial capacity of 850 mA h g-1 and maintain their stability for 800 cycles at a C-rate of 1 C (1675 mA h g-1), suggesting the applicability of GO in future rechargeable batteries.

6.
ACS Appl Mater Interfaces ; 10(48): 41439-41449, 2018 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-30406998

RESUMO

Three azahelicene derivatives with electron-rich bis(4-methoxyphenyl)amino or bis( p-methoxyphenyl)aminophenyl groups at the terminals were deliberately designed, synthesized, and characterized as hole-transporting materials (HTMs) for perovskite solar cells (PSCs). Optical and thermal properties, energy level alignments, film morphologies, hole extraction ability, and hole mobility were studied in detail. PSCs using the newly synthesized molecules as HTMs were fabricated. A maximum power conversion efficiency (PCE) of 17.34% was observed for the bis( p-methoxyphenyl)amino-substituted derivative (SY1) and 16.10% for the bis( p-methoxyphenyl)aminophenyl-substituted derivative (SY2). Longer-chain substituent such as hexyloxy group greatly diminishes the efficiency. In addition, the dopant-free devices fabricated with SY1 as the HTM shows an average PCE of 12.13%, which is significantly higher than that of spiro-OMeTAD (7.61%). The ambient long-term stability test revealed that after 500 h, the devices prepared from SY1 and SY2 retained more than 96% of its initial performance, which is much improved than the reference device with standard spiro-OMeTAD as the HTM under the same conditions. Detailed material cost analysis reveals that the material cost for SY1 is less than 8% of that for spiro-OMeTAD. These results provide a useful direction for designing a new class of HTMs to prepare highly efficient and more durable PSCs.

7.
J Vis Exp ; (134)2018 04 25.
Artigo em Inglês | MEDLINE | ID: mdl-29757268

RESUMO

This manuscript describes how to design and fabricate efficient inverted solar cells, which are based on a two-dimensional conjugated small molecule (SMPV1) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM), by utilizing ZnO nanorods (NRs) grown on a high quality Al-doped ZnO (AZO) seed layer. The inverted SMPV1:PC71BM solar cells with ZnO NRs that grew on both a sputtered and sol-gel processed AZO seed layer are fabricated. Compared with the AZO thin film prepared by the sol-gel method, the sputtered AZO thin film exhibits better crystallization and lower surface roughness, according to X-ray diffraction (XRD) and atomic force microscope (AFM) measurements. The orientation of the ZnO NRs grown on a sputtered AZO seed layer shows better vertical alignment, which is beneficial for the deposition of the subsequent active layer, forming better surface morphologies. Generally, the surface morphology of the active layer mainly dominates the fill factor (FF) of the devices. Consequently, the well-aligned ZnO NRs can be used to improve the carrier collection of the active layer and to increase the FF of the solar cells. Moreover, as an anti-reflection structure, it can also be utilized to enhance the light harvesting of the absorption layer, with the power conversion efficiency (PCE) of solar cells reaching 6.01%, higher than the sol-gel based solar cells with an efficiency of 4.74%.


Assuntos
Nanotubos/química , Óxido de Zinco/química , Fontes de Energia Elétrica
8.
Sci Rep ; 8(1): 8146, 2018 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-29802298

RESUMO

Employing CO2-based polymer in electronic applications should boost the consumption of CO2 feedstocks and provide the potential for non-permanent CO2 storage. In this study, polypropylene carbonate (PPC) is utilized as a dielectric and substrate material for organic thin film transistors (OTFTs) and organic inverter. The PPC dielectric film exhibits a surface energy of 47 mN m-1, a dielectric constant of 3, a leakage current density of less than 10-6 A cm-2, and excellent compatibility with pentacene and PTCDI-C8 organic semiconductors. Bottom-gate top-contact OTFTs are fabricated using PPC as a dielectric; they exhibits good electrical performance at an operating voltage of 60 V, with electron and hole mobilities of 0.14 and 0.026 cm2 V-1 s-1, and on-to-off ratios of 105 and 103, respectively. The fabricated p- and n-type transistors were connected to form a complementary inverter that operated at supply voltages of 20 V with high and low noise margins of 85 and 69%, respectively. The suitability of PPC as a substrate is demonstrated through the preparation of PPC sheets by casting method. The fabricated PPC sheets has a transparency of 92% and acceptable mechanical properties, yet they biodegraded rapidly through enzymatic degradation when using the lipase from Rhizhopus oryzae.

9.
ACS Appl Mater Interfaces ; 10(21): 17973-17984, 2018 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-29737157

RESUMO

Further technological development of perovskite solar cells (PSCs) will require improvements in power conversion efficiency and stability, while maintaining low material costs and simple fabrication. In this Research Article, we describe top-illuminated ITO-free, stable PSCs featuring microcavity structures, wherein metal layers on both sides on the active layers exerted light interference effects in the active layer, potentially increasing the light path length inside the active layer. The optical constants (refractive index and extinction coefficient) of each layer in the PSC devices were measured, while the optical field intensity distribution was simulated using the transfer matrix method. The photocurrent densities of perovskite layers of various thicknesses were also simulated; these results mimic our experimental values exceptionally well. To modify the cavity electrode surface, we deposited a few nanometers of ultrathin MoO3 (2, 4, and 6 nm) in between the Ag and poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) layers provide hydrophobicity to the Ag surface and elevate the work function of Ag to match that of the hole transport layer. We achieved a power conversion efficiency (PCE) of 13.54% without hysteresis in the device containing a 4 nm-thick layer of MoO3. In addition, we fabricated these devices on various cavity electrodes (Al, Ag, Au, Cu); those prepared using Cu and Au anodes displayed improved device stability of up to 72 days. Furthermore, we prepared flexible PSCs having a PCE of 12.81% after incorporating the microcavity structures onto poly(ethylene terephthalate) as the substrate. These flexible solar cells displayed excellent stability against bending deformation, maintaining greater than 94% stability after 1000 bending cycles and greater than 85% after 2500 bending cycles performed with a bending radius of 5 mm.

10.
ACS Appl Mater Interfaces ; 10(18): 15996-16004, 2018 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-29658267

RESUMO

Controlling circularly polarized (CP) states of light is critical to the development of functional devices for key and emerging applications such as display technology and quantum communication, and the compact circular polarization-tunable photon source is one critical element to realize the applications in the chip-scale integrated system. The atomic layers of transition metal dichalcogenides (TMDCs) exhibit intrinsic CP emissions and are potential chiroptical materials for ultrathin CP photon sources. In this work, we demonstrated CP photon sources of TMDCs with device thicknesses approximately 50 nm. CP photoluminescence from the atomic layers of tungsten diselenide (WSe2) was precisely controlled with chiral metamolecules (MMs), and the optical chirality of WSe2 was enhanced more than 4 times by integrating with the MMs. Both the enhanced and reversed circular dichroisms had been achieved. Through integrations of the novel gain material and plasmonic structure which are both low-dimensional, a compact device capable of efficiently manipulating emissions of CP photon was realized. These ultrathin devices are suitable for important applications such as the optical information technology and chip-scale biosensing.

11.
ChemSusChem ; 11(2): 415-423, 2018 01 23.
Artigo em Inglês | MEDLINE | ID: mdl-29131542

RESUMO

Here, we introduced benzo[ghi]perylenetriimide (BPTI) derivatives including monomer and twisted dimer (t-BPTI) as an alternative electron-transport layer (ETL) material to replace the commonly used PC61 BM in inverted planar heterojunction perovskite solar cells (PSCs). Moreover, the double ETL was applied in our PSCs with structure of glass/ITO/PEDOT:PSS/perovskite/BPTI/C60 or PDI-C4/BCP/Al. The use of a double ETL structure can effectively eliminate the leakage current. The devices with the t-BPTI/C60 double ETL yield an average power conversion efficiency of 10.73 % and a maximum efficiency of 11.63 %. The device based on the complete non-fullerene electron acceptors of t-BPTI/PDI-C4 as double ETL achieved maximum efficiency of 10.0 %. Moreover, it was found that the utilization of alloy t-BPTI+BPTI as ETL can effectively reduce the hysteresis effect of PSCs. The results suggest that BPTI-based electron-transport materials are potential alternatives for widely used fullerene acceptors in PSCs.


Assuntos
Compostos de Cálcio/química , Fontes de Energia Elétrica , Fulerenos/química , Imidas/química , Óxidos/química , Perileno/análogos & derivados , Energia Solar , Titânio/química , Dimerização , Elétrons , Microscopia de Força Atômica , Estrutura Molecular , Perileno/química , Semicondutores
12.
ACS Appl Mater Interfaces ; 10(3): 2566-2573, 2018 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-29281245

RESUMO

The presence of toxic lead (Pb) remains a major obstruction to the commercial application of perovskite solar cells. Although antimony (Sb)-based perovskite-like structures A3M2X9 can display potentially useful photovoltaic behavior, solution-processed Sb-based perovskite-like structures usually favor the dimer phase, which has poor photovoltaic properties. In this study, we prepared a layered polymorph of Cs3Sb2I9 through solution-processing and studied its photovoltaic properties. The exciton binding energy and exciton lifetime of the layer-form Cs3Sb2I9 were approximately 100 meV and 6 ns, respectively. The photovoltaic properties of the layered polymorph were superior to those of the dimer polymorph. A solar cell incorporating the layer-form Cs3Sb2I9 exhibited an open-circuit voltage of 0.72 V and a power conversion efficiency of 1.5%-the highest reported for an all-inorganic Sb-based perovskite.

13.
ACS Nano ; 11(12): 12436-12445, 2017 12 26.
Artigo em Inglês | MEDLINE | ID: mdl-29207236

RESUMO

In this paper we describe a modified (AEG/CH) coated separator for Li-S batteries in which the shuttling phenomenon of the lithium polysulfides is restrained through two types of interactions: activated expanded graphite (AEG) flakes interacted physically with the lithium polysulfides, while chitosan (CH), used to bind the AEG flakes on the separator, interacted chemically through its abundance of amino and hydroxyl functional groups. Moreover, the AEG flakes facilitated ionic and electronic transfer during the redox reaction. Live H-cell discharging experiments revealed that the modified separator was effective at curbing polysulfide shuttling; moreover, X-ray photoelectron spectroscopy analysis of the cycled separator confirmed the presence of lithium polysulfides in the AEG/CH matrix. Using this dual functional interaction approach, the lifetime of the pure sulfur-based cathode was extended to 3000 cycles at 1C-rate (1C = 1670 mA/g), decreasing the decay rate to 0.021% per cycle, a value that is among the best reported to date. A flexible battery based on this modified separator exhibited stable performance and could turn on multiple light-emitting diodes. Such modified membranes with good mechanical strength, high electronic conductivity, and anti-self-discharging shield appear to be a scalable solution for future high-energy battery systems.

14.
Chem Commun (Camb) ; 53(92): 12450-12453, 2017 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-29099528

RESUMO

A hierarchical supramolecular hydrogel was self-assembled from a Fmoc-RGDS tetrapeptide and showed photo-controlled release directed by host-guest interaction. Multiple payloads, including vesicles, were successively released from a single peptide hydrogel.


Assuntos
Ciclodextrinas/química , Hidrogéis/química , Oligopeptídeos/química , Compostos Azo/química , Compostos Azo/efeitos da radiação , Ciclodextrinas/efeitos da radiação , Liberação Controlada de Fármacos , Fluoresceína-5-Isotiocianato/química , Corantes Fluorescentes/química , Hidrogéis/efeitos da radiação , Interações Hidrofóbicas e Hidrofílicas , Isomerismo , Oligopeptídeos/efeitos da radiação , Viscosidade
15.
ACS Appl Mater Interfaces ; 9(38): 32635-32642, 2017 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-28816434

RESUMO

Inorganic-organic hybrid perovskite solar cells (PSCs) are promising devices for providing future clean energy because of their low cost, ease of fabrication, and high efficiencies, similar to those of silicon solar cells. These materials have been investigated for their potential use in bifacial PSCs, which can absorb light from both sides of the electrodes. Here, we fabricated bifacial PSCs featuring transparent BCP/Ag/MoO3 rear electrodes, which we formed through low-temperature processing using thermal evaporation methods. We employed a comprehensive optical distribution program to calculate the distributions of the optical field intensities with constant thicknesses of the absorbing layer in the top electrode configuration. The best PSC having a transparent BCP/Ag/MoO3 electrode achieved PCEs of 13.49% and 9.61% when illuminated from the sides of the indium tin oxide and BCP/Ag/MoO3 electrodes, respectively. We observed significant power enhancement when operating this PSC using mirror reflectors and bifacial light illumination from both sides of the electrodes.

16.
Sci Rep ; 6: 34319, 2016 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-27698464

RESUMO

In this study, hybrid perovskite solar cells are fabricated using poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and poly(3-hexylthiophene-2,5-diyl) (P3HT) as dopant-free hole-transporting materials (HTMs), and two solution processes (one- and two-step methods, respectively) for preparing methylammonium lead iodide perovskite. By optimizing the concentrations and solvents of MEH-PPV solutions, a power conversion efficiency of 9.65% with hysteresis-less performance is achieved, while the device with 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'spirobifluorene (Spiro-OMeTAD) doped with lithium salts and tert-butylpyridine (TBP) exhibits an efficiency of 13.38%. This result shows that non-doped MEH-PPV is a suitable, low-cost HTM for efficient polymer-based perovskite solar cells. The effect of different morphologies of methylammonium lead iodide perovskite on conversion efficiency is also investigated by incident photon-to-electron conversion efficiency (IPCE) curves and electrochemical impedance spectroscopy (EIS).

17.
Opt Express ; 24(16): 17910-5, 2016 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-27505758

RESUMO

The ITO-free inverted SMPV1:PC71BM solar cells with an Al doped ZnO (AZO) transparent electrodes are fabricated. The AZO thin film prepared by pulsed laser deposition (PLD) technique exhibits high transmission (>85%) and low sheet resistance (~30 Ω/sq) and the power conversion efficiency (PCE) of devices based on AZO electrode can reach around 4%. To further enhance the light harvesting of the absorption layer of solar cells, ZnO nanorods interlayer is grown on the AZO layer before the deposition the active layer. The absorption spectrums of devices under various conditions are also simulated by RCWA method to identify the optical saturation length of the ZnO nanorods. The PCE of ITO-free inverted small molecule solar cell improved with ZnO nanorods can reach 6.6%.

18.
ACS Nano ; 10(1): 1454-61, 2016 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-26716765

RESUMO

Atomically thin two-dimensional transition-metal dichalcogenides (TMDCs) have attracted much attention recently due to their unique electronic and optical properties for future optoelectronic devices. The chemical vapor deposition (CVD) method is able to generate TMDCs layers with a scalable size and a controllable thickness. However, the TMDC monolayers grown by CVD may incorporate structural defects, and it is fundamentally important to understand the relation between photoluminescence and structural defects. In this report, point defects (Se vacancies) and oxidized Se defects in CVD-grown MoSe2 monolayers are identified by transmission electron microscopy and X-ray photoelectron spectroscopy. These defects can significantly trap free charge carriers and localize excitons, leading to the smearing of free band-to-band exciton emission. Here, we report that the simple hydrohalic acid treatment (such as HBr) is able to efficiently suppress the trap-state emission and promote the neutral exciton and trion emission in defective MoSe2 monolayers through the p-doping process, where the overall photoluminescence intensity at room temperature can be enhanced by a factor of 30. We show that HBr treatment is able to activate distinctive trion and free exciton emissions even from highly defective MoSe2 layers. Our results suggest that the HBr treatment not only reduces the n-doping in MoSe2 but also reduces the structural defects. The results provide further insights of the control and tailoring the exciton emission from CVD-grown monolayer TMDCs.

19.
Adv Mater ; 27(44): 7229-35, 2015 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-26444686

RESUMO

Zr-based porphyrin metal-organic framework (MOF-525) nanocrystals with a crystal size of about 140 nm are synthesized and incorporated into perovskite solar cells. The morphology and crystallinity of the perovskite thin film are enhanced since the micropores of MOF-525 allow the crystallization of perovskite to occur inside; this observation results in a higher cell efficiency of the obtained MOF/perovskite solar cell.


Assuntos
Compostos de Cálcio/química , Fontes de Energia Elétrica , Nanopartículas/química , Compostos Organometálicos/química , Óxidos/química , Energia Solar , Titânio/química
20.
ACS Appl Mater Interfaces ; 7(40): 22542-50, 2015 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-26389528

RESUMO

In this study, we combined two small-molecule donors-a diketopyrrolopyrrole-based small molecule (SMD) and a benzodithiophene-based molecule (BDT6T)-with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) to form ternary blend solar cells. The power conversion efficiency of the binary SMD:PC61BM bulk heterojunction solar cell improved from 4.57 to 6.28% after adding an appropriate amount BDT6T as a guest. We attribute this 37% improvement in device performance to the complementary absorption behavior of BDT6T and SMD, as evidenced by the increase in the short circuit current. After addition of BDT6T to form the ternary blend, the crystallinity and morphology of the active layer were enhanced. For example, the features observed in the ternary active layers were finer than those in the binary blends. This means that BDT6T as a third component in the ternary blend has effective role on both the absorption and the morphology. In addition, adding BDT6T to form the ternary blend also led to an increase in the open-circuit voltage. Our findings suggest that the preparation of such simple all-small-molecule ternary blends can be an effective means of improving the efficiency of photovoltaic devices.

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