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Organic tandem solar cells with 18.6% efficiency
摘要： Tandem organic photovoltaic (TOPV) cell is one of the technologies to harvest more solar power by staking two or more OPV devices on top of each other. Recently, the highest power conversion efficiency (PCE) ever achieved was 17.3%. Herein, this paper simulates the response of 676 different TOPV devices that consists front and back OPV cells. For this purpose, this paper uses the best 26 single-cell OPV devices to form the TOPV front and back cells combinations. The results show that there are some new TOPVs that can exceed 17.3% efficiency limit for TOPV. Also, in this work thickness optimization was performed for these new TOPV devices with an objective of efficiency maximization. As a result, using PBDTS-TDZ: ITIC in the front cells and PTB7-Th: O6T-4F:PC71BM in the back cell gives 18.6% efficiency. Likewise, the TOPV of PBDB-T-2F:TfIF-4FIC in the front cell with PTB7-Th:O6T-4F:PC71BM in the back cell gives 18.06% efficiency.
关键词： Organic materials,External quantum efficiency,Tandem organic solar cells,Optimization,Simulation
更新于2025-09-16 10:30:52
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Hybrid plasmonic metasurfaces
摘要： Plasmonic metasurfaces based on ensembles of distributed metallic nanostructures can absorb, scatter, and in other ways shape light at the nanoscale. Forming hybrid plasmonic metasurfaces by combination with other materials opens up for new research directions and novel applications. This perspective highlights some of the recent advancements in this vibrant research field. Particular emphasis is put on hybrid plasmonic metasurfaces comprising organic materials and on concepts related to switchable surfaces, light-to-heat conversion, and hybridized light-matter states based on strong coupling.
关键词： strong coupling,hybrid plasmonic metasurfaces,organic materials,light-to-heat conversion,switchable surfaces
更新于2025-09-16 10:30:52
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Ultrasensitive Organic‐Modulated CsPbBr <sub/>3</sub> Quantum Dot Photodetectors via Fast Interfacial Charge Transfer
摘要： The integration of organic materials with colloidal quantum dots (QDs) has the merits the advantages of the molecular diversity and photoelectric tunability for ultrasensitive photodetector applications. Herein, a uniform CsPbBr3 QD layer is sandwiched between the same poly-(N, N′-bis-4-butylphenyl-N, N′-bisphenyl) benzidine (Poly-TPD) and phenyl-C61-butyric acid methyl ester (PCBM) (1:1) organic blend films. The CsPbBr3 QD layer efficiently absorbs the excitation light, where the generated exciton can sufficiently diffuse to the interface of QD and organic blend layers for efficient charge separation and effective gate modulation. Owing to the desirable heterojunction at the interface, the dark current is substantially suppressed, while the photocurrent is increased in comparison with those of pristine QDs photodetectors. The ultrafast charge transfer time (≈300 ps) from QDs to organic blend layer measured by the time-resolved transient absorption spectroscopy is potentially benefit the enhanced electron–hole pair dissociation. The solution-processed, organic (Poly-TPD:PCBM blend)-modulated CsPbBr3 QDs photodetector are exhibited ultrasensitive photoresponse abilities in terms of in terms of noise equivalent power (NEP = 1 × 10?16 W Hz?0.5), ILight/IDark ratio (2 × 103), and the a specific detectivity (D* = 4.6 × 1013 Jones). The results will be a starting point for ultrasensitive next-generation light detection technologies.
关键词： detectivity,organic materials,solution-processed,photodetectors,perovskite quantum dots
更新于2025-09-12 10:27:22
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Reference Module in Materials Science and Materials Engineering || Excitonic Model versus Band Gap Model in Organic Materials
摘要： The binding energy Eb of an optical excitation is a key parameter for the understanding of the opto-electronic properties of organic solids in general and of conjugated polymers in particular. It controls the dissociation of an electronic excitation of either singlet or triplet character into a pair of free charges as well as the reverse process, i.e., the recombination of an electron–hole (eh) pair yielding an excitation that can decay radiatively or nonradiatively. If Eb is large, photogeneration of charge carriers is an endothermic, inefficient process. It is obvious that in an organic solar cell (OSC) one would like Eb to be as small as possible, while in a light emitting diode (LED) it is the opposite because charge recombination requires a driving force. In this article an outline of the problem of defining the exciton binding in a molecular solid will be presented followed by experimental and theoretical advances and a critical review of relevant conceptual frameworks with particular emphasis on conjugated polymers.
关键词： Organic Materials,Conjugated Polymers,Band Gap Model,Opto-electronic Properties,Exciton Binding Energy
更新于2025-09-11 14:15:04
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Material Identification of Single-Organic Particles Realized by Observing Their Field-Induced Translations
摘要： A method is proposed that can efficiently identify the material of a single-organic particle; the identification is realized by improving an apparatus formerly used to observe the field-induced translations of particles. Using this new setup, the material of an unidenti?ed organic particle can be determined without consuming the sample. Specifically, the diamagnetic susceptibility χDIA of the particle was obtained from its translating velocity induced in a field-gradient produced by an Nd magnetic circuit, and its material was identi?ed by comparing the experimental χDIA value with a list of published values. In principle, the proposed method of identi?cation based on the χDIA value is effective even for micrometersized particles because the mass measurement of the sample is unnecessary. Hence, the method can be used to thoroughly extract and identify a rare material from a mixture of heterogeneous particles without consuming the sample, before performing a re?ned analysis.
关键词： microgravity condition,Nd–Fe–B magnet,magnetic separation,material separation,organic materials
更新于2025-09-10 09:29:36
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Organic and hybrid resistive switching materials and devices
摘要： The explosive increase in digital communications in the Big Data and internet of Things era spurs the development of universal memory that can run at high speed with high-density and nonvolatile storage capabilities, as well as demonstrating superior mechanical flexibility for wearable applications. Among various candidates for the next-generation information storage technology, resistive switching memories distinguish themselves with low power consumption, excellent downscaling potential, easy 3D stacking, and high CMOS compatibility, fulfilling key requirements for high-performance data storage. Employing organic and hybrid switching media in addition allows light weight and flexible integration of molecules with tunable device performance via molecular design-cum-synthesis strategy. In this review, we present a timely and comprehensive review of the recent advances in organic and hybrid resistive switching materials and devices, with particular attention on their design principles for electronic property tuning and flexible device performance. The current challenges posed with development of organic and hybrid resistive switching materials and flexible memory devices, together with their future perspectives, are also discussed.
关键词： flexible electronics,organic materials,resistive switching memories,nonvolatile storage,hybrid materials
更新于2025-09-09 09:28:46
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Nano Focus: IR vibrational crystallography visualizes molecular orientation on the nanoscale
摘要： The orientation of molecules is of central importance in determining the photophysical properties of organic materials, such as mobility of charge carriers and ions. These orientation-dependent properties of materials further control their functionalities in biological systems and electronic devices, including organic light-emitting diodes and solar cells. Until now, optical crystallography has failed to yield high-resolution images of molecular arrangement, due to the diffraction-limited response, weak photon–material interaction between x-rays and organic materials, or sample damage. A group of researchers from the University of Colorado Boulder and Lawrence Berkeley National Laboratory has developed a new mapping technique called infrared scattering-type scanning near-field optical microscopy (IR s-SNOM), which can identify the molecular arrangement of subdomains smaller than hundreds of nanometers.
关键词： IR vibrational crystallography,IR s-SNOM,organic materials,molecular orientation,nanoscale
更新于2025-09-09 09:28:46
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Efficient and Long-lived Room Temperature Organic Phosphorescence: Theoretical Descriptors for Molecular Designs
摘要： Room-temperature phosphorescence (RTP) with long afterglow from pure organic materials has attracted great attentions for their potential applications in biological imaging, digital encryption and optoelectronic device and so on. Organic materials have been long considered to be non-phosphorescence owing to the weak molecular spin-orbit coupling and highly sensitive to temperature. However, recently, some purely organic compounds can demonstrate highly efficient RTP with long afterglow upon aggregation while others fail. Namely, it remains a challenge to expound the underline mechanisms. In this study, we present the molecular descriptors to character the phosphorescence efficiency and lifetime. For prototypical RTP system consists of carbonyl group and π-conjugated segments, the excited states can be regarded as admixture of n→π* (with portion α) and π→π* (portion β). Starting from phosphorescent process and El-Sayed rule, we deduced that (i) the intersystem crossing (ISC) rate of S1→Tn is mostly governed by the modification of the product of α and β, and (ii) the ISC rate of T1→S0 is determined by the β value of T1. Thus, the descriptors (γ=α×β, β) can be employed to describe the RTP character of organic molecules. From hybrid quantum mechanics and molecular mechanics (QM/MM) calculations, we illustrated the relationships amongst the descriptors (γ, β), phosphorescent efficiency and lifetime, as well as spin-orbit coupling constants. We stressed that the large γ and β values are favorable to the strong and long-lived RTP in organic materials. Experiments have reported confirmations of these molecular design rules.
关键词： Organic materials,Molecular descriptors,Room-temperature phosphorescence,QM/MM calculations,Spin-orbit coupling
更新于2025-09-04 15:30:14
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Discrete Dimers of Redox-Active and Fluorescent Perylene Diimide-Based Rigid Isosceles Triangles in the Solid State
摘要： The development of rigid covalent chiroptical organic materials, with multiple, readily available redox states, which exhibit high photoluminescence is of particular importance in relation to both organic electronics and photonics. The chemically stable, thermally robust and redox-active perylene diimide (PDI) fluorophores have received ever-increasing attention owing to their excellent fluorescence quantum yields in solution. Planar PDI derivatives, however, generally suffer from aggregation-caused emission quenching in the solid state. Herein, we report on the design and synthesis of two chiral isosceles triangles wherein one PDI fluorophore and two pyromellitic diimide (PMDI) or naphthalene diimide (NDI) units are arranged in a rigid cyclic triangular geometry. The optical, electronic and magnetic properties of the rigid isosceles triangles are fully characterized by a combination of optical spectroscopies, X-ray diffraction, cyclic voltammetry, and computational modeling techniques. Single-crystal X-ray diffraction analysis shows that both isosceles triangles form discrete, nearly cofacial PDI-PDI π-dimers in the solid state. While the triangles exhibit fluorescence quantum yields of almost unity in solution, the dimers in the solid state exhibit very weak — yet at least an order of magnitude higher — excimer fluorescence yield in comparison with the almost completely quenched fluorescence of a reference PDI. The triangle containing both NDI and PDI subunits shows superior intramolecular energy transfer from the lowest excited singlet state of the NDI to that of the PDI subunit. Cyclic voltammetry suggests that both isosceles triangles exhibit multiple, easily accessible and reversible redox states. Applications beckon in arenas related to molecular optoelectronic devices.
关键词： intramolecular energy transfer,isosceles triangles,rigid covalent chiroptical organic materials,naphthalene diimide,excimer fluorescence,redox-active,π-dimers,photoluminescence,perylene diimide,pyromellitic diimide,cyclic voltammetry
更新于2025-09-04 15:30:14
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Scalable Synthesis of Naphthothiophene and Benzodithiophene Scaffolds as π-Conjugated Synthons for Organic Materials
摘要： The synthesis on a gram-scale and the full characterization of naphtho[1,2-b]thiophene and benzo[1,2-b:6,5-b']dithiophene 4-carboxylate esters bearing 2-octyldodecyl side chains, and their stannylated and brominated derivatives, suitable for their insertion into π-conjugated polymers is described. The fully soluble and processable synthons are obtained through a cascade sequence of reactions, namely direct arylation and cross aldol condensation, which create an effective pathway for the annulation and π-extension of suitable, commercially available reagents. The newly reported synthesis are compared, whenever possible, using ‘green chemistry metrics’ with literature synthesis, showing dramatic improvements.
关键词： cross aldol condensation,annulation,heterocycles,organic materials,direct arylation
更新于2025-09-04 15:30:14