Search NASA⌕ Search

SEARCH · Search NASA

Results for “asymmetric”

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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Tuning the Mechanical and Electric Properties of Conjugated Polymer Semiconductors: Side–Chain Design Based on Asymmetric Benzodithiophene Building Blocks

Understanding molecular design rules for stretchable polymer semiconductors is important for enabling next generation stretchable electronic circuits. To simultaneously improve both electrical properties and mechanical stretchability, a design strategy is reported in introducing conjugated rigid fused-rings with bulky side groups in semiconducting polymers. In this work, the understanding of this design concept is improved by systematically investigating the effect of different types of bulky side groups asymmetrically substituted on conjugated polymer semiconductor backbones. Specifically, four types of side groups are investigated, including naphthalene (NaPh), biphenyl (PhPh), thienylphenyl (ThPh), and alkylphenyl (C4Ph), asymmetrically substituted on benzodithiophene units, namely asy-BDT. With the four types of side groups installed on BDT-containing conjugated polymers in an asymmetrical fashion, it is observed that they reduced the polymer chain aggregation and film crystallinity, hence improving the film stretchability. Furthermore, the fully conjugated polymer back-bone allows maintenance of good charge carrier mobilities. Specifically, polymer PDPP-C4Ph (with C4Ph side groups) shows the highest mobility in the fully stretchable transistor and maintained its mobility even after being subjected to hundreds of stretching-releasing cycles at 25% strain. Altogether, the results provide anunderstanding of the use of asymmetrically substituted fused-ring conjugated polymer structures to tune mechanical and charge transport properties.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Unidirectional Sidechain Engineering to Construct Dual‐Asymmetric Acceptors for 19.23 % Efficiency Organic Solar Cells with Low Energy Loss and Efficient Charge Transfer

Abstract Achieving both high open‐circuit voltage ( V oc ) and short‐circuit current density ( J sc ) to boost power‐conversion efficiency (PCE) is a major challenge for organic solar cells (OSCs), wherein high energy loss ( E loss ) and inefficient charge transfer usually take place. Here, three new Y‐series acceptors of mono‐asymmetric asy‐YC11 and dual‐asymmetric bi‐asy‐YC9 and bi‐asy‐YC12 are developed. They share the same asymmetric D 1 AD 2 (D 1 =thieno[3,2‐ b ]thiophene and D 2 =selenopheno[3,2‐ b ]thiophene) fused‐core but have different unidirectional sidechain on D 1 side, allowing fine‐tuned molecular properties, such as intermolecular interaction, packing pattern, and crystallinity. Among the binary blends, the PM6 : bi‐asy‐YC12 one has better morphology with appropriate phase separation and higher order packing than the PM6 : asy‐YC9 and PM6 : bi‐asy‐YC11 ones. Therefore, the PM6 : bi‐asy‐YC12‐based OSCs offer a higher PCE of 17.16 % with both high V oc and J sc , due to the reduced E loss and efficient charge transfer properties. Inspired by the high V oc and strong NIR‐absorption, bi‐asy‐YC12 is introduced into efficient binary PM6 : L8‐BO to construct ternary OSCs. Thanks to the broadened absorption, optimized morphology, and furtherly minimized E loss , the PM6 : L8‐BO : bi‐asy‐YC12‐based OSCs achieve a champion PCE of 19.23 %, which is one of the highest efficiencies among these annealing‐free devices. Our developed unidirectional sidechain engineering for constructing bi‐asymmetric Y‐series acceptors provides an approach to boost PCE of OSCs.

Chemistry↗
DOE OSTI2024

A Difluoro‐Methoxylated Ending‐Group Asymmetric Small Molecule Acceptor Lead Efficient Binary Organic Photovoltaic Blend

Abstract Developing a new end group for synthesizing asymmetric small molecule acceptors (SMAs) is crucial for achieving high‐performance organic photovoltaics (OPVs). Herein, an asymmetric small molecule acceptor, BTP‐BO‐4FO, featuring a new difluoro‐methoxylated end‐group is reported. Compared to its symmetric counterpart L8‐BO, BTP‐BO‐4FO exhibits an upshifted energy level, larger dipole moment, and more sequential crystallinity. By adopting two representative and widely available solvent additives (1‐chloronaphthalene (CN) and 1,8‐diiodooctane (DIO)), the device based on PM6:BTP‐BO‐4FO (CN) photovoltaic blend demonstrates a power conversion efficiency (PCE) of 18.62% with an excellent open‐circuit voltage (V OC ) of 0.933 V, which surpasses the optimal result of L8‐BO. The PCE of 18.62% realizes the best efficiencies for binary OPVs based on SMAs with asymmetric end groups. A series of investigations reveal that optimized PM6:BTP‐BO‐4FO film demonstrates similar molecular packing motif and fibrillar phase distribution as PM6:L8‐BO (DIO) does, resulting in comparable recombination dynamics, thus, similar fill factor. Besides, it is found PM6:BTP‐BO‐4FO possesses more efficient charge generation, which yields betterV OC –J SC balance. This study provides a new ending group that enables a cutting‐edge efficiency in asymmetric SMA‐based OPVs, enriching the material library and shed light on further design ideas.

Chemistry↗
DOE OSTI2025

Highly tail-asymmetric lipids interdigitate and cause bidirectional ordering

Phospholipids form structurally and compositionally diverse membranes. A less studied type of compositional diversity involves phospholipid tail variety. Some phospholipids contain two acyl tails which differ in length. These tail-asymmetric lipids are shown to contribute to temperature sensitivity, oxygen adaptability, and membrane fluidity. Membranes of a highly virulent intracellular bacterium, Francisella tularensis, contain highly tail-asymmetric 1-lignoceroyl-2-decanoyl-sn-glycero-3-phosphatidylethanolamine (XJPE) lipids which were previously shown to inhibit inflammatory responses in host cells. XJPE tails have unusually high asymmetry, and how they contribute to membrane properties on a molecular level is unknown. Here, we use small angle X-ray scattering and molecular dynamics simulations to investigate how varying XJPE ratios alters properties of simple membranes. Our results demonstrate that at high concentration they promote liquid-to-gel transition in otherwise liquid membranes, while at low concentration they are tolerated well, minimally altering membrane properties. In liquid membranes, XJPE lipids dynamically adopt two main conformations; with the long tail extended into the opposing leaflet or bent-back residing in its own leaflet. When added to both leaflets XJPE primarily adopts an extended confirmation, while asymmetric addition results in more bent-back orientations. The former increases tail ordering and the latter decreases it. XJPE tails adopt different conformations that induce composition- and leaflet-dependent bidirectional effect on membrane fluidity and this suggests that Francisella tularensis could use tail asymmetry to facilitate vesicle fusion and destabilize host cells. The effect of tail-asymmetric lipids on complex membranes should be further investigated to reveal the regulatory roles of high tail asymmetry.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Photoenzymatic Asymmetric Hydroamination for Chiral Alkyl Amine Synthesis

Chiral alkyl amines are common structural motifs in pharmaceuticals, natural products, synthetic intermediates, and bioactive molecules. An attractive method to prepare these molecules is the asymmetric radical hydroamination; however, this approach has not been explored with dialkyl amine-derive nitrogen-centered radicals since designing a catalytic system to generate the aminium radical cation, to suppress deleterious side reactions such as α-deprotonation and H atom abstraction, and to facilitate enantioselective hydrogen atom transfer is a formidable task. Herein, we describe the application of photoenzymatic catalysis to generate and harness the aminium radical cation for asymmetric intermolecular hydroamination. In this reaction, the flavin-dependent ene-reductase photocatalytically generates the aminium radical cation from the corresponding hydroxylamine and catalyzes the asymmetric intermolecular hydroamination to furnish the enantioenriched tertiary amine, whereby enantioinduction occurs through enzyme-mediated hydrogen atom transfer. Furthermore, this work highlights the use of photoenzymatic catalysis to generate and control highly reactive radical intermediates for asymmetric synthesis, addressing a long-standing challenge in chemical synthesis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Asymmetric ether solvents for high-rate lithium metal batteries

Recent electrolyte solvent design based on weakening lithium-ion solvation have shown promise in enhancing cycling performance of Li-metal batteries. However, they often face slow redox kinetics and poor cycling reversibility at high rate. Here we report using asymmetric solvent molecules substantially accelerates Li redox kinetics. Asymmetric ethers (1-ethoxy-2-methoxyethane, 1-methoxy-2-propoxyethane) showed higher exchange current densities and enhanced high-rate Li 0 plating/stripping reversibility compared to symmetric ethers. Adjusting fluorination levels further improved oxidative stability and Li 0 reversibility. The asymmetric 1-(2,2,2-trifluoro)-ethoxy-2-methoxyethane, with 2 M lithium bis(fluorosulfonyl)imide, exhibited high exchange current density, oxidative stability, compact solid–electrolyte interphase (~10 nm). This electrolyte exhibited superior performance among state-of-the-art electrolytes, enabling over 220 cycles in high-rate Li (50 μm)||LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811, 4.9 mAh cm −2 ) cells and for the first time over 600 cycles in anode-free Cu | |Ni95 pouch cells (200 mAh) under electric vertical take-off and landing cycling protocols. Our findings on asymmetric molecular design strategy points to a new pathway towards achieving fast redox kinetics for high-power Li-metal batteries.

batteries↗
DOE OSTI2022

Exploration of the bio-analogous asymmetric C–C coupling mechanism in tandem CO 2 electroreduction

C–C coupling is a critical step of CO 2 fixation in constructing the carbon skeleton of value-added multicarbon products. The Wood–Ljungdahl pathway is an efficient natural process through which microbes transform CO 2 into methyl and carbonyl groups and subsequently couple them together. This asymmetric coupling mechanism remains largely unexplored in inorganic CO 2 electroreduction. Here we experimentally validate the asymmetric coupling pathway through isotope-labelled co-reduction experiments on a Cu surface where 13 CH 3 I and 12 CO are co-fed externally as the methyl and the carbonyl source, respectively. Isotope-labelled multicarbon oxygenates were detected, which confirms an electrocatalytic asymmetric coupling on the Cu surface. We further employed tandem Cu–Ag nanoparticle systems in which *CH x and *CO intermediates can be generated to achieve asymmetric C–C coupling for a practical CO 2 electroreduction. We found that the production of multicarbon oxygenates is correlated with the generation rate of two intermediate indicators, CH 4 and CO. By aligning their rates, the oxygenates generation rate can be maximized.

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

Asymmetric side-chain engineering in semiconducting polymers: a platform for greener processing and post-functionalization of organic electronics

Organic semiconducting polymers are a powerful platform for the design of next-generation technologies due to their excellent optoelectronic properties and solution processability, allowing access to low-cost and scalable manufacturing techniques such as spin-coating, slot-die coating and roll-to-roll printing. However, their extended π-conjugation results in low solubility, requiring the use of toxic halogenated solvents to generate thin films and devices. Furthermore, accessible post-functionalization of semiconductors toward the development of multifunctional devices and sensors remains a challenge due to limited solid-state chemistry for alkyl side chains. In this work, an asymmetric side-chain engineering approach was used to introduce terminal hydroxyl moieties alongside traditional solubilizing branched alkyl chains into an isoindigo-based polymer. The hydroxyl moieties led to significantly improved processability in alcohol-based solvents without sacrificing electronic performance in thin film organic field-effect transistors. Solid state morphologies of the thin films processed from both alcohol-based and traditional halogenated solvents were further characterized using atomic force microscopy and grazing incidence wide angle X-ray scattering. Additionally, Cryo-EM was utilized in order to characterize the role of asymmetric side-chain functionality in solution state aggregation. The versatility of this design was further probed using fluorescein isothiocyanate to directly functionalize the asymmetric polymer in thin film. Furthermore, this facile solid-state post-functionalization further demonstrates asymmetric side-chain engineering to be a viable approach toward the development of sustainably manufactured multifunctional electronics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Asymmetric Rowland circle geometries for spherically bent crystal analyzers in laboratory and synchrotron applications

Spherically bent crystal analyzers (SBCAs) are the dominant high-resolution hard X-ray optic in the ongoing rebirth of laboratory-based X-ray absorption fine structure (XAFS) and X-ray emission spectroscopy (XES) as well as in synchrotron methods such as high energy resolution fluorescence detection (HERFD) and non-resonant X-ray Raman scattering (XRS). In the overwhelming majority of cases, SBCAs are implemented in a ‘symmetric’ configuration on the Rowland circle, wherein the diffracting crystal plane is nominally coincident with the analyzer surface. We report here comprehensive investigations of ‘asymmetric’ operation of SBCA on the Rowland circle, wherein the diffracting crystal plane is not coincident with the optical surface of the analyzer. First, we have developed a laboratory spectrometer for XAFS and XES that is specialized for asymmetric SBCA operation. Here we find several benefits, including the capacity to use a single SBCA over a very wide energy range via ‘hkl hopping’ and the frequent ability to eliminate Johann error, the most prevalent energy-broadening mechanism when using SBCA symmetrically on the Rowland circle. Second, we expand these ideas to synchrotron facilities with a demonstration study of HERFD and XRS where asymmetric operation also provided advantage. Our results suggest that large-array systems for HERFD augmented with an additional mechanical degree of freedom could streamline user operation and also indicate benefits to XRS in the asymmetric configuration, where larger solid angle, larger sample-to-detector distance, and decreased Johann error can be achieved simultaneously.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Competition between mass-symmetric and asymmetric fission modes in 258 Md produced in the 4 He+ 254 Es reaction

Earlier studies of spontaneous fission of heavy actinides found that the fission-fragment mass distribution suddenly changes from predominantly asymmetric to symmetric, when the mass number of the fissioning nucleus becomes larger than A c = 257. We have measured for the first time fission-fragment mass and totalkinetic-energy (TKE) distributions of the excited compound nucleus 258 Md∗ (Z = 101), populated in the reaction 4 He + 254 Es, using the rare radioactive target isotope 254 Es with a short half-life, T1/2 = 275.7 d. The fission of 258 Md∗ can be interpreted as involving three fission modes: one mass-asymmetric and two mass-symmetric fission modes, the latter two are manifested by different TKE values. In this assumption, symmetric and asymmetric fission modes have nearly similar yields at the excitation energy of 15.0 MeV. The spectrum of 18.0 MeV can be explained as due to the increase of asymmetric fission mode.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Compromising Charge Generation and Recombination with Asymmetric Molecule for High-Performance Binary Organic Photovoltaics with Over 18% Certified Efficiency

Balancing the charge generation and recombination constitutes a major challenge to break the current limit of organic photovoltaics (OPVs). Here, to address this issue, an asymmetric non-fullerene acceptor, namely the AC9, is developed and high-performance OPV with a champion efficiency of 18.43% (18.1% certified) is demonstrated. This represents the record value among binary OPVs. Comprehensive analysis on exciton dissociation, charge collection, carrier transport, and recombination has been carried out, unveiling that the improved device performance of asymmetric AC9-based OPVs is originated from a better compromise between charge generation and non-radiative charge recombination, compared with the corresponding symmetric ones. This work provides a high-performing molecule and paves the way for high-performance OPVs through asymmetric molecular design.

36 MATERIALS SCIENCE↗
DOE OSTI2022

A Flexible, Redox-Active, Aqueous Electrolyte-Based Asymmetric Supercapacitor with High Energy Density Based on Keratin-Derived Renewable Carbon

This work exploits the advantage of asymmetric configuration over symmetric supercapacitor in designing high energy density flexible devices from two active electrode materials–keratin-based renewable-resource hierarchically porous carbon and hydrous ruthenium oxide (RuO 2 ). Here, the asymmetric device exhibits significantly high capacitance. Conventional estimation of energy storage parameters, however, cannot be applied for devices with a Faradaic energy storage contribution via redox charge transfer mechanism. Therefore, this work applies a precise measurement of pseudocapacitance contribution at various scan rates to correct the device data that reveals effective capacitance of 120 F g –1 with the energy density of 37 W h kg –1 at 776 W kg –1 . It also retains excellent rate capability, >74% at high current density 25 A g –1 . The charge storage activity and device stability can be further enhanced by introducing redox-active electrolytes that improve specific capacitance, but the rate capabilities deteriorate at high current densities. Further, the principle of asymmetric electrode design is applied to fabricate a bending-tolerant, flexible device by depositing active electrode material on wire-shaped current collector followed by coupling those separated with polyvinyl alcohol gel containing redox electrolyte; it yields 36.8 mF cm –1 specific capacitance at a 0.2 mA cm –1 current density.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Raising the Asymmetric Catalytic Efficiency of Chiral Covalent Organic Frameworks by Tuning the Pore Environment

Chiral covalent organic frameworks (COFs) hold considerable promise in the realm of heterogeneous asymmetric catalysis. However, fine-tuning the pore environment to enhance both the activity and stereoselectivity of chiral COFs in such applications remains a formidable challenge. In this study, we have successfully designed and synthesized a series of clover-shaped, hydrazone-linked chiral COFs, each with a varying number of accessible chiral pyrrolidine catalytic sites. Remarkably, the catalytic efficiencies of these COFs in the asymmetric aldol reaction between cyclohexanone and 4-nitrobenzaldehyde correlate well with the number of accessible pyrrolidine sites within the frameworks. Further, the COF featuring nearly one pyrrolidine moiety at each nodal point demonstrated excellent reaction yields and enantiomeric excess (ee) values, reaching up to 97 and 83%, respectively. The findings not only underscore the profound impact of a deliberately controlled chiral pore environment on the catalytic efficiencies of COFs but also offer a new perspective for the design and synthesis of advanced chiral COFs for efficient asymmetric catalysis.

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

High-Voltage Sodium–Metal Batteries with Asymmetric Fluoroalkoxylated Organoborate Anion Chemistry

The high reactivity of sodium (Na) metal restricts its compatibility to ether-based electrolytes, while the poor oxidative stability of ethers precludes their coupling to high-voltage cathodes, fundamentally limiting the operating voltage and energy density of sodium–metal batteries (SMBs). We present here a coordination-asymmetry strategy to reconcile this thermodynamic mismatch by generating in situ an asymmetric fluoroalkoxylated organoborate anion, [FB(OCH(CF 3 ) 2 ) 3 ] − (BOF – ), via a Lewis acid–base adduct reaction in ether electrolyte. The asymmetric ligand architecture differentiates oxidative and fluorination pathways: oxidizable B–O moieties mediate controlled interfacial reconstruction, whereas the terminal B–F units supply fluorine for chemical passivation. This self-adaptive chemistry yields nanoscale, conformal, compositionally graded interphases: a boron-oxide/boron-oxycarbide-rich cathode-electrolyte interphase (CEI) that mitigates ether oxidation and a bilayered inorganic–organic solid–electrolyte interphase (SEI) that regulates Na deposition. The nanostructured interphases enable highly reversible Na plating/stripping with an average Coulombic efficiency (CE) of 99.98% and sustain stable 4.3 V operation of anode-free SMBs in oxidation-prone ether electrolytes. Furthermore, this work establishes asymmetric boron coordination as a molecular-level design principle for creating chemically adaptive interphases that overcome the redox asymmetry in energy-dense electrochemical systems.

Anions↗
DOE OSTI2023

Antimony nanobelt asymmetric membranes for sodium ion battery

In this study, composite asymmetric membranes containing antimony (Sb) nanobelts are prepared via a straightforward phase inversion method in combination with post-pyrolysis treatment. Sb nanobelt asymmetric membranes demonstrate improved cyclability and specific capacity as the alloy anode of sodium ion battery compared to Sb nanobelt thin films without asymmetric porous structure. The unique structure can effectively accommodate the large volume expansion of Sb-based alloy anodes, prohibit the loss of fractured active materials, and aid in the formation of stable artificial solid electrolyte interphases as evidenced by an outstanding capacity retention of ~98% in 130 cycles at 60 mA g -1 . A specific capacity of ~600 mAh g -1 is obtained at 15 mA g -1 (1/40C). When the current density is increased to 240 mA g -1 , ~80% capacity can be maintained (~480 mAh g -1 ). The relations among phase inversion conditions, structures, compositions, and resultant electrochemical properties are revealed through comprehensive characterization.

25 ENERGY STORAGE↗
DOE OSTI2024

Increased spatial coherence length from an asymmetric crystal reflection at grazing exit

Coherent X-ray imaging is an active field at synchrotron sources. The images rely on the available coherent flux over a limited field of view. At many synchrotron beamlines a double-crystal monochromator (DCM) is employed in a standard nondispersive arrangement. For coherent diffraction imaging it is advantageous to increase the available field of view by increasing the spatial coherence length (SCL) of a beam exiting such a DCM. Here, Talbot interferometry data together with ray-tracing simulations for a (+ − − +) four-reflection experimental arrangement are presented, wherein the first two reflections are in the DCM and the final fourth reflection is asymmetric at grazing exit. Analyses of the interferometry data combined with the simulations show that compared with the beam exiting the DCM a gain of 76% in the SCL was achieved, albeit with a factor of 20 reduction in flux density, which may not be a severe penalty at a synchrotron beamline. Previous efforts reported in the literature to increase the SCL that employed asymmetric crystal diffraction at grazing incidence are also discussed. A much reduced SCL is found presently in simulations wherein the same asymmetric crystal is set for grazing incidence instead of grazing exit. In addition, the present study is compared and contrasted with two other means of increasing the SCL. These are (i) focusing the beam onto an aperture to act as a secondary source, and (ii) allowing the beam to propagate in vacuum an additional distance along the beamline.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Over 15% Efficiency Polymer Solar Cells Enabled by Conformation Tuning of Newly Designed Asymmetric Small‐Molecule Acceptors

Abstract The prosperous period of polymer solar cells (PSCs) has witnessed great progress in molecule design methods to promote power conversion efficiency (PCE). Designing asymmetric structures has been proved effective in tuning energy level and morphology, which has drawn strong attention from the PSC community. Two hepta‐ring and octa‐ring asymmetric small molecular acceptors (SMAs) (IDTP‐4F and IDTTP‐4F) with S‐shape and C‐shape confirmations are developed to study the relationship between conformation shapes and PSC efficiencies. The similarity of absorption and energy levels between two SMAs makes the conformation a single variable. Additionally, three wide‐bandgap polymer donors (PM6, S1, and PM7) are chosen to prove the universality of the relationship between conformation and photovoltaic performance. Consequently, the champion PCE afforded by PM7: IDTP‐4F is as high as 15.2% while that of PM7: IDTTP‐4F is 13.8%. Moreover, the S‐shape IDTP‐4F performs obviously better than their IDTTP‐4F counterparts in PSCs regardless of the polymer donors, which confirms that S‐shape conformation performs better than the C‐shape one. This work provides an insight into how conformations of asymmetric SMAs affect PCEs, specific functions of utilizing different polymer donors to finely tune the active‐layer morphology and another possibility to reach an excellent PCE over 15%.

Guo, Qing↗
DOE OSTI2020

Asymmetric Alkoxy and Alkyl Substitution on Nonfullerene Acceptors Enabling High‐Performance Organic Solar Cells

Abstract In this paper, a strategy of asymmetric alkyl and alkoxy substitution is applied to state‐of‐the‐art Y‐series nonfullerene acceptors (NFAs), and it achieves great performance in organic solar cell (OSC) devices. Since alkoxy groups can have a significant influence on the material properties of NFAs, alkoxy substitution is applied to the Y6 molecule in a symmetric manner. The resulting molecule (named Y6‐2O), despite showing improved open‐circuit voltage ( V oc ), yields extremely poor performance due to low solubility and excessive aggregation properties, a change that is due to the conformational locking effect of alkoxy groups. In contrast, asymmetric alkyl and alkoxy substitution on Y6, yields a molecule named Y6‐1O that can maintain the positive effect of V oc improvement and obtain reasonably good solubility. The resulting molecule Y6‐1O enables highly efficient nonfullerene OSCs with 17.6% efficiency and the asymmetric side‐chain strategy has the potential to be applied to other NFA‐material systems to further improve their performance.

Chen, Yuzhong↗