Search NASA⌕ Search

SEARCH · Search NASA

Results for “Fullerene Molecules”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Slow spin relaxation in single endohedral fullerene molecules

Well-protected magnetization, tunable quantum states, and long spin-relaxation time are desired for the use of magnetic molecules in spintronics and quantum information technologies. In this work, endohedral fullerene molecules M@C 28 with different transition-metal cores were explored through systematic first-principles calculations and spin dynamics analyses. Many of them have bias-tunable structure, stable magnetization, and sizable magnetic anisotropy energy. Furthermore, some of them may have spin-relaxation time up to several milliseconds for their quantum spin states at high temperature (~10 K) after full consideration of spin-vibration couplings. In conclusion, our results suggest that these M@C 28 provide a rich pool of single-molecule magnets for diverse applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1993

Electric propulsion using C.sub.60 molecules

Fullerene propellants, which are stable carbon cage structures composed of even numbers of carbon atoms in the range of about 32 to 200 atoms, particularly a combination of conveniently obtainable C.sub.60 and C.sub.70, may be carried in solid form in a spacecraft, sublimated to produce the appropriate molecular propellant such as C.sub.60 or C.sub.70, which may then be ionized by DC discharge or RF radiation to efficiently produce specific impulses in the range above 1000 lbf -s/lbm.

Leifer, Stephanie D.↗
DOE OSTI2021

Negative Ion Formation in Complex Heavy Systems

The project’s primary objective is to gain a fundamental theoretical understanding of the near-threshold electron attachment mechanism in low energy electron elastic scattering from complex heavy systems through the calculation of integral and differential cross sections and extract reliable electron affinities (EAs). The complex angular momentum (CAM), also known as Regge-pole methodology wherein is fully embedded the crucial electron-electron correlations and the core polarization interaction, is used for the investigations. Regge trajectories allow us to probe electron attachment at the fundamental level near threshold, thereby uncovering new manifestations, including the mechanism of nanocatalysis, and determine reliable EAs. Low-energy electron elastic scattering total cross sections (TCSs) for the lanthanide and actinide atoms and the fullerene molecules are calculated. From the TCSs ground, metastable and excited states anionic binding energies (BEs) are extracted and compared with the available measured and/or calculated EAs. Significantly, our calculated ground state anionic BEs correspond to the theoretically challenging to calculate EAs and they are used to assess the reliability of existing EAs. Doubly charged negative ions of atoms and molecules are proposed as novel tunable catalysts and demonstrated in the oxidation of water into peroxide. Negatively charged fullerene molecules are used to catalyze water oxidation to peroxide and water synthesis from H 2 and O 2 as well. Violation of time-reversal and particle-hole symmetries in strongly correlated Fermi systems are reviewed with the collaboration involving the International Laboratory of Fermi Condensation.

74 ATOMIC AND MOLECULAR PHYSICS↗
NASA NTRS2005

Making Macroscopic Assemblies of Aligned Carbon Nanotubes

A method of aligning and assembling single-wall carbon nanotubes (SWNTs) to fabricate macroscopic structures has been invented. The method entails suspending SWNTs in a fluid, orienting the SWNTs by use of a magnetic and/or electric field, and then removing the aligned SWNTs from suspension in such a way as to assemble them while maintaining the alignment. SWNTs are essentially tubular extensions of fullerene molecules. It is desirable to assemble aligned SWNTs into macroscopic structures because the common alignment of the SWNTs in such a structure makes it possible to exploit, on a macroscopic scale, the unique mechanical, chemical, and electrical properties that individual oriented SWNTs exhibit at the molecular level. Because of their small size and high electrical conductivity, carbon nanotubes, and especially SWNTs, are useful for making electrical connectors in integrated circuits. Carbon nanotubes can be used as antennas at optical frequencies, and as probes in scanning tunneling microscopes, atomic-force microscopes, and the like. Carbon nanotubes can be used with or instead of carbon black in tires. Carbon nanotubes are useful as supports for catalysts. Ropes of SWNTs are metallic and, as such, are potentially useful in some applications in which electrical conductors are needed - for example, they could be used as additives in formulating electrically conductive paints. Finally, macroscopic assemblies of aligned SWNTs can serve as templates for the growth of more and larger structures of the same type. The great variety of tubular fullerene molecules and of the structures that could be formed by assembling them in various ways precludes a complete description of the present method within the limits of this article. It must suffice to present a typical example of the use of one of many possible variants of the method to form a membrane comprising SWNTs aligned substantially parallel to each other in the membrane plane. The apparatus used in this variant of the method (see figure) includes a reservoir containing SWNTs dispersed in a suspending agent (for example, dimethylformamide) and a reservoir containing a suitable solvent (for example, water mixed with a surfactant). By use of either pressurized gas supplied from upstream or suction from downstream, the suspension of SWNTs and the solvent are forced to mix and flow into a tank. A filter inside the tank contains pores small enough to prevent the passage of most SWNTs, but large enough to allow the passage of molecules of the solvent and suspending agent. The filter is oriented perpendicular to the flow path. A magnetic field parallel to the plane of the filter is applied. The success of the method is based on the tendency of SWNTs to become aligned with their longitudinal axes parallel to an applied magnetic field. The alignment energy of an SWNT increases with the length of the SWNT and the magnetic-field strength. In order to obtain an acceptably small degree of statistical deviation of SWNTs of a given length from alignment with a magnetic field, one must make the field strong enough so that the thermal energy associated with rotation of an SWNT away from alignment is less than the alignment energy.

Smalley, Richard E.↗
NASA NTRS2002

Combustion Synthesis of Fullerenes and Fullerenic Nanostructures In Microgravity

The objectives of the proposed research were to determine the effects of gravity on fullerenes formation in flames and, based on the observed effects, to develop fundamental understanding of fullerenes formation and to identify engineering principles for fullerenes production. The research method consisted of the operation of laminar diffusion flames under normal- and reduced-gravity conditions, and the collection from the flames and subsequent analysis of condensables including any fullerenes present, using coupled high performance liquid chromatography/mass spectrometry and high resolution transmission electron microscopy. The focus included fullerene molecules C60 and C70 and fullerenic nanostructures including tubes, spherules and other shapes. The normal-gravity experiments were performed at MIT and complementary reduced-gravity experiments were to have been contributed by NASA. The independent variables of interest are gravity, fuel type, fuel/oxygen ratio, pressure, gas velocity at burner, diluent type and concentration. Given the large number of variables and the absence of data on either fullerene formation in diffusion flames or gravitational effects on fullerene formation in diffusion or premixed flames, the first part of the work was exploratory while the later part involved detailed study of the most interesting mechanisms. Samples of condensable material from laminar low pressure benzene/argon/oxygen diffusion flames were collected and analyzed by high-performance liquid chromatography to determine the yields of fullerenes, and by high-resolution transmission electron microscopy (HRTEM) to characterize the fullerenic material, i.e., curved-layer nanostructures, on and within the soot particles. The highest concentration of fullerenes was always detected just above the visible stoichiometric surface of a flame. The percentage of fullerenes in the condensable material increases with decreasing pressure. The overall highest amount of fullerenes was found for a surprisingly high dilution fuel with argon. The maximum flame temperature seems to be of minor importance in fullerene formation. The HRTEM analysis of the soot showed an increase of the curvature of the carbon layers, and hence increased fullerenic character. After this maximum, the curvature decreases. In addition to the soot, the samples included fullerenic nanostructures, such as tubes and spheroids including highly-ordered multilayered or onion-like structures. The soot itself shows highly ordered regions that appear to have been cells of ongoing fullerenic nanostructure formation.

Howard, Jack B.↗
NASA NTRS2009

Heavy Ion Formation in Titan's Ionosphere: Magnetospheric Introduction of Free Oxygen and a Source of Titan's Aerosols?

Discovery by Cassini's plasma instrument of heavy positive and negative ions within Titan's upper atmosphere and ionosphere has advanced our understanding of ion neutral chemistry within Titan's upper atmosphere, primarily composed of molecular nitrogen, with approx.2.5% methane. The external energy flux transforms Titan's upper atmosphere and ionosphere into a medium rich in complex hydrocarbons, nitriles and haze particles extending from the surface to 1200 km altitudes. The energy sources are solar UV, solar X-rays, Saturn's magnetospheric ions and electrons, solar wind and shocked magnetosheath ions and electrons, galactic cosmic rays (CCR) and the ablation of incident meteoritic dust from Enceladus' E-ring and interplanetary medium. Here it is proposed that the heavy atmospheric ions detected in situ by Cassini for heights >950 km, are the likely seed particles for aerosols detected by the Huygens probe for altitudes <100km. These seed particles may be in the form of polycyclic aromatic hydrocarbons (PAH) containing both carbon and hydrogen atoms CnHx. There could also be hollow shells of carbon atoms, such as C60, called fullerenes which contain no hydrogen. The fullerenes may compose a significant fraction of the seed particles with PAHs contributing the rest. As shown by Cassini, the upper atmosphere is bombarded by magnetospheric plasma composed of protons, H(2+) and water group ions. The latter provide keV oxygen, hydroxyl and water ions to Titan's upper atmosphere and can become trapped within the fullerene molecules and ions. Pickup keV N(2+), N(+) and CH(4+) can also be implanted inside of fullerenes. Attachment of oxygen ions to PAH molecules is uncertain, but following thermalization O(+) can interact with abundant CH4 contributing to the CO and CO2 observed in Titan's atmosphere. If an exogenic keV O(+) ion is implanted into the haze particles, it could become free oxygen within those aerosols that eventually fall onto Titan's surface. The process of freeing oxygen within aerosols could be driven by cosmic ray interactions with aerosols at all heights. This process could drive pre-biotic chemistry within the descending aerosols. Cosmic ray interactions with grains at the surface, including water frost depositing on grains from cryovolcanism, would further add to abundance of trapped free oxygen. Pre-biotic chemistry could arise within surface microcosms of the composite organic-ice grains, in part driven by free oxygen in the presence of organics and any heat sources, thereby raising the astrobiological potential for microscopic equivalents of Darwin's "warm ponds" on Titan.

Sittler, E. C., Jr.↗
NASA NTRS1996

Electron Impact Excitation of C60 Adducts: Flourescence From C60OH and C60H Species

An investigation concerning possible visible and UV photon emissions by gas phase C(sub 60) ( and C(sub 70)) samples under electron impact excitation was caried out in the 180-750 nm spectral region. Radiation resembling OH (A (sup 2)pi {leads to}X (sup 2){summation}) emission bands and H Balmer series was observed. Based on our investigations, it is concluded that none of the observed emission was associated with the fullerene molecule itself but with the C(sub 60)OH and C(sub 60)H adducts (which are present in the fullerene samples). We also conclude that in these adducts, simultaneous ionization and excitation take place under electron impact and the excited ionic species (C(sub 60)+OH* and C(sub 60)+H*) decay by radiation which was observed in our experiments. These surprising results reveal an interesting new character of buckyball adducts.

gas phase emissions buckyball buckyball adducts fu↗
NASA NTRS1994

Effect of the Thermal Stability and Reactivity of Fullerenes on Ion Engine Propellant Applications

Because vapor phase fullerene molecules collide with high temperature surfaces at both the cathode in DC discharges and at the walls of vapor sources, knowledge of the thermal stability and material compatibility of fullerenes is important for ion thruster applications. Here, we present a study of the high temperature behavior of fullerenes. We find that when C 60 and C 7O are maintained at temperatures above 1073 K, or are wxposed to hot metal surfaces, significant degradation occurs. We find an activation energy of 261.5 kJ/mol for this process. At temperatures below 873 K, no breakdown of fullerenes can be detected, even after heating for 6 hours. The effect of these findings on C 60 ion thruster design is discussed. Our present C 60 ion thruster experiment is also described.

fullerenes↗
NASA NTRS1990

The formation and structure of circumstellar and interstellar dust

The intriguing abundance of long linear carbon chain molecules in some dark clouds and in circumstellar shells is still not well understood. Recent laboratory studies which have probed this problem indicate that when carbon vapor nucleates to form particles, linear chains and hollow cage molecules (fullerenes) also form at more-or-less the same time. The results have consequences for the formation, structures and spectroscopic properties of the molecular and dust components ejected from cool carbon-rich stars. A most interesting result of the experimental observations relates to the probability that a third character in addition to the chains and grains, the C(sub 60) molecule probably in the form of the ion C(sub 60)(sup +) in the less shielded regions, is present and perhaps responsible for some of the ubiquitously observed interstellar spectroscopic features such as the Diffuse Interstellar Features, the 2170A UV Absorption or perhaps some of the Unidentified Infrared Bands. Further study of small carbon particles which form in the gas phase has resulted in the discovery that they have quasi-icosahedral spiral shell structures. The role that such species may play in the interstellar medium as well as that played by C(sub 60) (or C sub 60 sup +) should soon be accessible to verification by a combination of laboratory experiment and astronomical spectroscopy.

Kroto, H. W.↗
NASA NTRS1997

Formation of Carbon Nanotube Based Gears: Quantum Chemistry and Molecular Mechanics Study of the Electrophilic Addition of o-Benzyne to Fullerenes, Graphene, and Nanotubes

Considerable progress has been made in recent years in chemical functionalization of fullerene molecules. In some cases, the predominant reaction products are different from those obtained (using the same reactants) from polycyclic aromatic hydrocarbons (PAHs). One such example is the cycloaddition of o-benzyne to C60. It is well established that benzyne adds across one of the rings in naphthalene, anthracene and other PAHs forming the [2+4] cycloaddition product (benzobicyclo[2.2.2.]-octatriene with naphthalene and triptycene with anthracene). However, Hoke et al demonstrated that the only reaction path for o-benzyne with C60 leads to the [2+2] cycloaddition product in which benzyne adds across one of the interpentagonal bonds (forming a cyclobutene ring in the process). Either reaction product results in a loss of aromaticity and distortion of the PAH or fullerene substrate, and in a loss of strain in the benzyne. It is not clear, however, why different products are preferred in these cases. In the current paper, we consider the stability of benzyne-nanotube adducts and the ability of Brenner's potential energy model to describe the structure and stability of these adducts. The Brenner potential has been widely used for describing diamondoid and graphitic carbon. Recently it has also been used for molecular mechanics and molecular dynamics simulations of fullerenes and nanotubes. However, it has not been tested for the case of functionalized fullerenes (especially with highly strained geometries). We use the Brenner potential for our companion nanogear simulations and believe that it should be calibrated to insure that those simulations are physically reasonable. In the present work, Density Functional theory (DFT) calculations are used to determine the preferred geometric structures and energetics for this calibration. The DFT method is a kind of ab initio quantum chemistry method for determining the electronic structure of molecules. For a given basis set expansion, it is comparable in accuracy to the MP2 method (better than Hartree Fock, but less accurate than more extensive electron correlation methods such as MP4 or CCSD). However, for systems with large numbers of basis functions it more efficient than any other methods that include electron correlation effects. In this presentation we show the results of DFT calculations for the reaction of benzyne with naphthalene, C60, and nanotube models. We compare energies for [2+2] and [2+4] cycloaddition products. The preferred products for the naphthalene and C60 reactions have been determined by experiment and, thus, these cases serve as a validation of our quantum chemical approach. We also compare the DFT and Brenner potential results. Finally we can predict the likelihood of reaction between benzyne and nanotubes.

Jaffe, Richard↗
DOE OSTI2020

Tunable Kondo Resonance at a Pristine Two-Dimensional Dirac Semimetal on a Kondo Insulator

The proximity of two different materials leads to an intricate coupling of quasiparticles so that an unprecedented electronic state is often realized at the interface. Here, we demonstrate a resonance-type many-body ground state in graphene, a nonmagnetic two-dimensional Dirac semimetal, when grown on SmB 6 , a Kondo insulator, via thermal decomposition of fullerene molecules. This ground state is typically observed in three-dimensional magnetic materials with correlated electrons. Above the characteristic Kondo temperature of the substrate, the electron band structure of pristine graphene remains almost intact in this work. As temperature decreases, however, the Dirac Fermions of graphene become hybridized with the Sm 4 f states. Remarkable enhancement of the hybridization and Kondo resonance is observed with further cooling and increasing charge-carrier density of graphene, evidencing the Kondo screening of the Sm 4 f local magnetic moment by the conduction electrons of graphene at the interface. These findings manifest the realization of the Kondo effect in graphene by the proximity of SmB 6 that is tuned by the temperature and charge-carrier density of graphene.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2022

Ferroelectrics and photovoltaics in endohedral fullerenes-based van der Waals heterostructures

Using the density functional theory calculations, we studied the ferroelectric, electronic, and optical properties of a series of bias-controllable endohedral fullerene molecules (TM@C28, TM = Ti-Ni). One important finding is that Cr@C28 has a large electric dipole moment and an appropriate bandgap (∼1.2 eV). By sandwiching Cr@C28 molecules between two graphene or transition metal dichalcogenide layers, the heterostructures may combine strong ferroelectricity and excellent optical properties. This paves the way for the development of two-dimensional van der Waals ferroelectric-photovoltaic materials.

Li, Jie (ORCID:0000000237334587)↗
DOE OSTI2025

Ionization of Free and Confined Atoms and Ions (Final Technical Report)

Over the almost 22-year duration of this theoretical research project, a great deal of progress has been made in the understanding of the ionization of free and confined atomic and molecular systems along with a recent particular emphasis upon studies of the ultrafast time-delay phenomenon in the photoemission process. Our methods have emphasized the role of many-body interactions and relativistic effects in the various processes we have studied. The advances that we have made over the course of this project have been in the areas nondipole effects in the photoionization process, inner-shell photoemission from negative atomic ions, excited state photoionization of neutral atoms and positive atomic ions, Cooper minima in quadrupole photoionization, relativistic interaction in the photoionization of atoms and negative atomic ions, photoionization of the fullerene molecule C 60 along with the photoionization of atomic and molecular systems confined in the C 60 molecule, confinement resonances in endohedral atom photoemission, interchannel coupling effects in photoionization, Wigner time delay in free and confined atoms and ions, angular effects in Wigner time delay in atomic photoionization, photoionization of superheavy atoms and the influence of core relaxation on the photoionization of atomic systems, among others. In the course of this project, we have had extensive collaboration with experimentalists where we have explained the physics of numerous measurements and pointed the way to new laboratory investigations with our calculations. We have also collaborated with a number of theorists as well. Thus, owing to these many collaborations with scientists not funded by DOE, we have leveraged the DOE support rather considerably. To illustrate the depth and breadth of the theoretical investigations, listed below are the 138 refereed and invited publications that cite DOE support. These publications detail the many contributions made over the period of this project.

74 ATOMIC AND MOLECULAR PHYSICS↗
NASA NTRS2005

Gears Based on Carbon Nanotubes

Gears based on carbon nanotubes (see figure) have been proposed as components of an emerging generation of molecular- scale machines and sensors. In comparison with previously proposed nanogears based on diamondoid and fullerene molecules, the nanotube-based gears would have simpler structures and are more likely to be realizable by practical fabrication processes. The impetus for the practical development of carbon-nanotube- based gears arises, in part, from rapid recent progress in the fabrication of carbon nanotubes with prescribed diameters, lengths, chiralities, and numbers of concentric shells. The shafts of the proposed gears would be made from multiwalled carbon nanotubes. The gear teeth would be rigid molecules (typically, benzyne molecules), bonded to the nanotube shafts at atomically precise positions. For fabrication, it may be possible to position the molecular teeth by use of scanning tunneling microscopy (STM) or other related techniques. The capability to position individual organic molecules at room temperature by use of an STM tip has already been demonstrated. Routes to the chemical synthesis of carbon-nanotube-based gears are also under investigation. Chemical and physical aspects of the synthesis of molecular scale gears based on carbon nanotubes and related molecules, and dynamical properties of nanotube- based gears, have been investigated by computational simulations using established methods of quantum chemistry and molecular dynamics. Several particularly interesting and useful conclusions have been drawn from the dynamical simulations performed thus far: The forces acting on the gears would be more sensitive to local molecular motions than to gross mechanical motions of the overall gears. Although no breakage of teeth or of chemical bonds is expected at temperatures up to at least 3,000 K, the gears would not work well at temperatures above a critical range from about 600 to about 1,000 K. Gear temperature could probably be controlled by use of coolant gases. For a given application, the gears would work well at temperatures below the critical range, provided that the rotational energy was less than the energy required to tilt the teeth through an angle of 20 . The predominant mechanism of gear failure would be slippage caused by tilting of teeth. Gears would resume functioning if the slipping gears were decelerated sufficiently.

Jaffe, Richard↗
DOE OSTI2025

Charge Transfer and Recombination Pathways through Fullerene Guests in Porphyrin-Based MOFs

Porphyrin-based metal–organic frameworks (MOFs) offer a unique platform for building porous donor–acceptor networks that exhibit long-lived charge separation and transport upon incorporation of electron acceptor guest species. Here, in this work, porphyrin-based MOFs, PCN-222(H 2 ) and PCN-222(Zn), synthesized as nanoparticle suspensions, are successfully infiltrated with fullerene acceptor molecules, C 60 or PC 61 BM, in both polar and nonpolar solvent environments. The location and relative binding strength of these guest species are evaluated through a combination of N 2 physisorption measurements, photoluminescence quenching, and UV–vis absorption titration experiments. Semiempirical tight binding calculations are used to screen potential locations of the fullerene guest within the MOF pores, and hybrid density functional theory (DFT)-computed interaction energies confirm the energetically favorable positions. The fundamental photophysics of these donor–acceptor host–guest combinations are probed using ultrafast transient absorption spectroscopy. Sub-picosecond electron transfer involving initial exciplex population is observed, with slow charge recombination lifetimes on the order of τ ~1 ns for all systems in both dimethylformamide and 1,4-dioxane. Charge recombination occurs through population of fullerene and/or framework porphyrin triplet states depending on the porphyrin metalation status. The photophysics of the fullerene-loaded MOFs are discussed in the context of relevant porphyrin–fullerene donor–acceptor molecules to highlight the unique role of the framework environment in dictating photoinduced electron transfer and decay pathways.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Verifying the structure-property-performance relationship of Y6-based small molecule acceptors by alkoxy-side chain isomerization and conjugated skeleton asymmetry

Non-fullerene small molecule acceptors (NF-SMAs) such as Y6 derivatives were the current working horse for the top performing polymer solar cells (PSCs). For this reason, numerous chemical modifications have been explored for establishing structure–property-performance relationship for Y6-based NF-SMAs. In this work, we explored the isomerization on asymmetrical Y6 derivatives by varying the position of alkoxy side chain on the thiophene linkage between the core and one of the end groups of Y6. The isomers with differences in conformational restriction raised by noncovalent interactions as well as steric hindrance revealed distinctive behavior in crystallization and polymorphism, which led to a significant contrast in PSC performances. Here the X-TO1 molecule with alkoxy side chain facing the end group (outward) displayed preferred molecular configuration and polymorph, delivering power conversion efficiency (PCE) of 15.63%, while its isomer X-TO2 showed coexisted polymorphs significantly increased the charge recombination in the PSC devices led to a low PCE around 3%. This structure–property-performance relationship not only highlighted the elegancy of isomerization in tuning the photovoltaic performances but also identified polymorphism as one of the causes for impairing photovoltaic performances of PSCs.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Electronic coarse-graining of long conjugated molecules: Case study of non-fullerene acceptors

By considering only one electronic state per molecule, charge transport models of molecular solids neglect intramolecular charge transfer. This approximation excludes materials with quasi-degenerate spatially separated frontier orbitals, such as non-fullerene acceptors (NFAs) and symmetric thermally activated delayed fluorescence emitters. By analyzing the electronic structure of room-temperature molecular conformers of a prototypical NFA, ITIC-4F, we conclude that the electron is localized on one of the two acceptor blocks with the mean intramolecular transfer integral of 120 meV, which is comparable with intermolecular couplings. Therefore, the minimal basis for acceptor–donor–acceptor (A–D–A) molecules consists of two molecular orbitals localized on the acceptor blocks. This basis is robust even with respect to geometry distortions in an amorphous solid, in contrast to the basis of two lowest unoccupied canonical molecular orbitals withstanding only thermal fluctuations in a crystal. The charge carrier mobility can be underestimated by a factor of two when using single site approximation for A–D–A molecules in their typical crystalline packings.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Synergistic Alignment of Low Aspect‐Ratio π‐Conjugated Molecules Enables Exceptional UV–vis–NIR Polarization Detection

Abstract Polarization detection enhances signal contrast and is widely utilized in diverse advanced applications. An ongoing challenge is the development of high‐performance polarization‐sensitive photodetectors based on optically anisotropic organic semiconductors, particularly in the near‐infrared (NIR) region. While uniaxially aligned π‐conjugated polymers with high aspect ratios exhibit strong linear dichroism and have shown promise, their limited NIR performance and heavy reliance on polymer material now represent critical limitations. Here, a breakthrough is reported in achieving giant linear dichroism and exceptional polarization detection with low aspect‐ratios (AR) non‐fullerene small‐molecule (NFSM) acceptors, extending polarization sensitivity from the UV–vis to the NIR range. An impressive dichroic ratio of 27.1 at 605 nm and 12.0 at 780 nm is demonstrated. The maximum polarization photocurrent ratio is 11.2 at 780 nm under parallel versus perpendicular polarized light. This unprecedented performance originates from synergistic molecular alignment, wherein NFSMs significantly enhance the uniaxial orientation of both the polymer matrix and the NFSMs themselves during self‐assembly and thermal annealing. Besides, such a linear‐polarization‐sensitive photodetectors (LPS‐PDs) are showcased in generating degree‐of‐linear‐polarization imaging. The work establishes NFSMs as a viable material system for next‐generation of organic LPS‐PDs and provides fundamental insights into structural origins of polarization sensitivity in low AR organic semiconductors.

Xue, Yingying↗