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Effect of processing conditions on additive DISC patterning of P3HT films
摘要： There is a critical need to develop a method to pattern semiconducting polymers for device applications on the sub-micrometer scale. Dopant induced solubility control (DISC) patterning is a recently published method for patterning semiconductor polymers that has demonstrated sub-micron resolution. DISC relies on the sequential addition of molecular dopants (here 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ)) to the conjugated polymer. In doped areas, the conjugated polymer is protected from dissolution while in undoped areas, the polymer dissolves into solution. Here we examine factors that affect the resolution of the developed pattern. Two factors are determined to be critical to pattern resolution, the initial crystallinity of the polymer, here poly(3-hexylthiophene) (P3HT), and the quality of the development solvent. We find that dopants diffuse more readily in highly crystalline films than in amorphous films of P3HT and that dopant diffusion reduces the fidelity of the resulting pattern. We also find that the choice of development solvent affects both the fidelity of the pattern and dopant distribution within the patterned polymer domains. Finally, we show that a dopant that diffuses more slowly than F4TCNQ in the P3HT film can be used to pattern the film with higher fidelity. These results together provide a road map for optimizing additive DISC patterning for any polymer/dopant pair.
关键词： crystallinity,semiconducting polymers,development solvent,pattern fidelity,P3HT,DISC patterning,F4TCNQ
更新于2025-11-21 11:08:12
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Morphology Tuning of ZnO/P3HT/P3HT-b-PEO Hybrid Films Deposited via Spray or Spin Coating
摘要： Hybrid films of zinc oxide (ZnO) and poly(3-hexylthiophen-2,5-diyl) (P3HT) show promising characteristics for application in hybrid bulk heterojunction solar cells (HBSCs). However, the incompatibility of ZnO and P3HT may lead to a reduced interface area, thus reducing the probability of exciton separation and consequently lowering solar cells efficiencies. Here, a diblock copolymer P3HT-b-poly(ethylene oxide) (PEO) is introduced to improve the interface between ZnO and P3HT. ZnO is synthesized via a block copolymer assisted sol-gel approach and the used zinc precursor is directly incorporated into the PEO blocks. Thus, the possibility of aggregation is reduced for both, the inorganic and the organic components and a good intermixing is ascertained. Two deposition methods, namely spray and spin coating are compared with respect to the resulting film structure, which is investigated with scanning electron microscopy (SEM) and time-of-flight grazing-incidence small-angle neutron scattering (TOF-GISANS) measurements. Both, the surface and inner morphologies reveal that the spin coated samples possess smaller and less diverse domain sizes than the sprayed films. Due to the advantage of spray coating in large-scale production, the morphology of the sprayed samples is tailored more meticulous by changing the weight fraction of ZnO in the films. The sprayed hybrid films show smaller domains and less aggregation with decreasing amount of ZnO. This reveals that both, the deposition method and composition of the ZnO/P3HT/P3HT-b-PEO hybrid films play an important role for the film morphology and thus for improving the performance of HBSCs in future application.
关键词： spray coating,morphology,spin coating,ZnO/P3HT/P3HT-b-PEO,TOF-GISANS
更新于2025-11-14 15:19:41
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Comparative solvent quality dependent crystallization in solvent vapor annealing of P3HT:PCBM thin films by in-situ GIWAXS
摘要： We present a novel in-depth study correlating multiple solvent properties (boiling point, vapor pressure, and solubilities of P3HT and PCBM) on P3HT and PCBM crystal growth kinetics in blend thin films via in-situ GIWAXS in conjunction with multiple substrate energies. Solvent vapor annealed (SVA) P3HT:PCBM films in a closed chamber, saturated with different solvents (o-dichlorobenzene (DCB), o-xylene, tetrahydrothiophene (THT), toluene, benzene, tetrahydrofuran (THF), and carbon disulfide (CS2)) were studied in real time. We observed that structure growth and dissolution kinetics of the both P3HT and PCBM crystals largely depend on physical properties of solvent and relative solubilities of P3HT and PCBM. The film morphology of the annealed films resulted in PCBM enrichment and occasional crystallization occurred at the solvent vapor saturated air interfaces. We observed strikingly different PCBM crystallization upon annealing of the films when cast from THF resulting in highly ordered PCBM crystals at the film surface. THF has high vapor pressure and relatively low solubilities for both P3HT and PCBM. At the other extreme CS2 produced the lowest crystallinity due to its very high vapor pressure such that the solvent evaporates before significant crystallization can occur. We characterized all the annealed samples using AFM, UV-Vis spectroscopy, and XPS. AFM probed topographic structures with coarsening of both the P3HT and PCBM domains at air surface by solvent annealing. We observe via UV-vis spectroscopy that, in general, intrachain electronic delocalization and interchain electron transitional jump due to π-π stacking increases in the post SVA films. This indicates that the chains are better organized with increased conjugation lengths. SVA has a substantial effect on P3HT monomer to PCBM ratio as determined by XPS at the polymer-air interface. In all cases, relative to the P3HT monomer:PCBM ratio of as-cast films from DCB, the air surfaces became more enriched by PCBM with SVA.
关键词： P3HT,GIWAXS,Morphology
更新于2025-09-23 15:23:52
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Photocathodic hydrogen evolution from catalysed nanoparticle films prepared from stable aqueous dispersions of P3HT and PCBM
摘要： Photo-assisted hydrogen evolution is achieved on photocathodes comprising of nanoparticles of poly(3-hexylthiophene) (npP3HT) and nanoparticles of phenyl-C61-butyric acid methyl ester (npPCBM) onto which ultra-low loadings of Pt nanoparticles are deposited. The nanoparticles, npP3HT and npPCBM, are prepared individually via miniemulsion using surfactants of opposite head group polarity. Aqueous dispersions of npP3HT:npPCBM, devoid of organic solvent, are cast conformally onto ITO-coated glass to yield water-insoluble bulk-heterojunction films. Pt is deposited photoelectrochemically onto ITO/npP3HT:npPCBM photocathodes and found to nucleate preferentially on PCBM nanoparticles. ITO/npP3HT:npPCBM/Pt photocathodes produce 65 μA/cm2 photocurrent under 100 mW/cm2 of visible light at 0.0 VSHE and liberate H2 gas. The photocurrents observed for electrodes prepared using npP3HT:npPCBM are twice as large, and the onset potential is ～0.4 V more positive than analogous photocathodes cast from nanoparticles each comprising an intimate blend of P3HT and PCBM. These are encouraging results for large scale synthesis of organic photoelectrochemical devices, given the simplicity of the photoelectrode, i.e., prepared from aqueous solutions and devoid of vacuum-deposited films such as charge transport layers and protective films.
关键词： Polymer nanoparticle,Photoelectrochemistry,P3HT: PCBM bulk-heterojunction,Solar hydrogen generation,Organic semiconductor,Mini-Emulsion
更新于2025-09-23 15:23:52
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Tuning charge transfer at the electron donor/acceptor assembly through vibration-induced aggregation of P3HT chains in solution
摘要： In this report, we developed a test platform to probe charge transfer at a model electron donor/acceptor system in which charge transfer rate is investigated through electrical contact resistance in a metal oxide/organic semiconductor/metal oxide structure using transmission line method (TLM). Aluminum (Al)-doped zinc oxide (AZO) films were adopted as source and drain electrodes. Molecular ordering of the organic semiconductor was systematically varied through vibration-induced aggregation (VIA) treatment of poly(3-hexylthiophene) (P3HT) polymer chains in solution to probe the effect of molecular ordering of P3HT (donor) in contact with AZO (acceptor) on interfacial charge transfer at the electron donor (P3HT)/acceptor (AZO) interface crucial in determining device performance of optoelectronic devices. Enhanced charge transfer at the donor/acceptor interface containing P3HT film treated with VIA process was demonstrated by reduction of the contact resistance via TLM. More efficient charge transfer at the AZO/sonicated-P3HT/AZO compared with AZO/pristine-P3HT/AZO results from enhanced charge carrier mobility of P3HT near the interface, blocking back-transfer of injected holes from P3HT to the AZO electrode, as demonstrated by theoretical prediction. Effect of VIA treatment on charge transfer at the electron donor/acceptor interface is confirmed through comparing the AZO/P3HT contact resistance depending on the degree of VIA for P3HT polymer chains by varying sonication time. Our work presented here demonstrates that improvement in structural arrangement of polymer chains leads to efficient charge transfer at interface.
关键词： Sonication,Charge transfer,p3ht
更新于2025-09-23 15:23:52
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Enhancing Viologen's Electrochromism by Incorporating Thiophene: A Step Toward All‐Organic Flexible Device
摘要： An all-organic electrochromic device seems to be a possibility with ethyl viologen (EV) and poly-3-hexylthiophene (P3HT), both being organic materials, showing complementary electrochromic pair for color switching. The EV-P3HT layer, sandwiched between ITO-coated glass substrates shows switching between maroon and blue with an applied bias of 1.4 V. Mechanism of the color switching has been examined using UV-Vis and Raman spectroscopies. The fabricated device shows optical modulation of 80%, switching time of 1 s while maintaining cycle life for a period of more than 600 s. The paradigm reported here inches toward realizing a flexible all-organic electrochromic device.
关键词： solid state devices,P3HT,ethyl viologen,electrochromic
更新于2025-09-23 15:22:29
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Setup to Study the in Situ Evolution of Both Photoluminescence and Absorption during the Processing of Organic or Hybrid Semiconductors
摘要： In situ measurement techniques, applied during the solution processing of novel semiconductors such as organic semiconductors or hybrid perovskites, have become more and more important to understand their film formation. In that context, it is crucial to determine how the optical properties, namely photoluminescence (PL) and absorption, evolve during processing. However, until now PL and absorption have mostly been investigated independently, significantly reducing the potential insights into film formation dynamics. To tackle this issue we present the development of a detection system that allows simultaneous measurement of full absorption and PL spectra during solution processing of the investigated film. We also present a spin-coater system attachable to the detection system, where the temperature of the substrate on which the film is processed can be changed. We performed test measurements by spin coating the well-known conjugated polymer P3HT demonstrating the potential of this technique. By considering absorption and corresponding PL, we extract the PL quantum yield (PLQY) during processing, which decreases with substrate temperature. Furthermore, we identify a significant red shift of the PL just prior to the onset of the aggregation process, indicating the importance of chain planarization prior to solid film formation.
关键词： photoluminescence,in situ measurement,organic semiconductors,hybrid perovskites,spin-coating,film formation,absorption,P3HT
更新于2025-09-23 15:21:21
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Influence of P3HT preaggregation process on performance of the P3HT:C60-PCBM solar cells
摘要： The bulk heterojunction based created by poly(3-hexyltiophene-2,5-diyl) (P3HT phenyl-C61-butyric acid methyl ester (C60-PCBM) it is well-known system used in organic solar cells. As the performance of such solar cells are very sensitive to the processing conditions of the active layers, we have focused attention to preaggregation process of P3HT in the aged solutions, which can be one of the reasons behind the different values of the reported efficiencies for this solar cell system. In this work, we present a systematic study of the influence of aging time of solutions mixture of P3HT:C60-PCBM in different solvents on the performance of the photovoltaic cells. The highest efficiency values were obtained from devices based on active layer dissolved in 1,2-dichlorobenzene. These values were stable even after 120 h of aging solutions, which means that the solution ageing process does not affect the final device properties. While, in chloroform and toluene solvents, efficiency of solar cells decreases within aging process. Our processing approach allows to better understanding the relationship between morphology of P3HT:C60-PCBM layer and device performances.
关键词： photovoltaics cells,Bulk-heterojunction,P3HT:C60-PCBM solar cells
更新于2025-09-23 15:21:01
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Highly Efficient Inorganic-Organic Heterojunction Solar Cells Based on Polymer and CdX (X=Se, Te) Quantum Dots: An Insight from a Theoretical Study
摘要： By using the density functional method, we explore the potentiality of recently synthesized CdX (X=Se, Te)QD/P3HT composites in solar energy conversion devices. Our study reveals that inorganic/organic hybrid CdXQD/P3HT nanocomposites with larger size of CdX QDs exhibit type-II band alignment, suggesting efficient charge separation upon photoexcitation. But for smaller size of QDs, the composites show type-I band alignment which are devoid of charge separation and thus are not suitable for solar cell applications. To remove this obstacle, we focus on chemical modification to polymer P3HT. The substitution of hydrogen at the beta position of each thiophene ring of polymer by electron withdrawing group (CN) results type-II band alignment and yield spatial charge separation even for smaller size of QDs. Finally, we calculated the powerconversion efficiency (PCE) of CdXQD and CN functionalized P3HT nanocomposites. The maximum calculated PCE value of 10.82% is achieved, which makes them immensely competitive with other reported heterojunction solar cells.
关键词： CdX (X=Se, Te)QD/P3HT composites,powerconversion efficiency,solar energy conversion,charge separation,type-II band alignment
更新于2025-09-23 15:21:01
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Hybrid P3HT: PCBM/GaN nanowire/Si cascade heterojunction for photovoltaic application
摘要： Poly (3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) are commonly used for the fabrication of organic photovoltaics (OPV). Efficiency limitations of OPVs could be circumvented by incorporation of inorganic nanostructures into organic blends. Again, integration of organic solar cells with well-developed silicon photovoltaic technology is ultimately desirable. In the present work, GaN nanowires with diameters of 25–50 nm and two lengths (200 and 500 nm) have been grown using molecular beam epitaxy technique. Solar-grade monocrystalline silicon wafers were used as substrates for nanowire synthesis. GaN nanostructures were incorporated into P3HT:PCBM photoactive layer in order to facilitate charge transfer between P3HT:PCBM and Si. Samples with and without nanowires were compared. Addition of nanowires led to the improvement in photovoltaic performance. Open circuit voltage has risen by 72% and short circuit current density by 200%. Series resistance has decreased 50 times, and power conversion efficiency has risen 20.7 times. Additional maxima are found in photocurrent spectrum corresponding to carriers being generated near GaN absorption edge. Moreover, external quantum efficiency peaks near GaN absorption edge, indicating transfer channel via the formation of current P3HT/GaN/Si cascade heterojunction. Mechanism explaining source of abovementioned improvement is proposed.
关键词： Molecular beam epitaxy,Energy conversion,P3HT,Solar cells,PCBM,GaN nanowires
更新于2025-09-23 15:21:01