Molecular Design Concept Research Articles

Reviving Multivalent‐Metal Anodes in Simple Salt Electrolytes via Component Modifier Design

AbstractUsing combinatory electrolyte blends represents an imperative avenue to achieve good magnesium (Mg)‐metal anode compatibility and commercial feasibility in fields of promising rechargeable Mg batteries. However, fundamental challenges of how to manipulate component modifier reactivity on molecule level still remain to be solved. Here, molecular structure design concepts towards seeking bromophenyl complex‐based component modifiers has been proposed according to implications of electron‐donating and/or electron‐withdrawing substituents on Br−C bond dissociation reactivity. Exceptional Mg electro‐plating/stripping properties (a stable cycle life of 250 days in Mg//Cu asymmetric cells) have been firstly achieved in a simple salt electrolyte with 1‐(3‐bromophenyl)‐N,N‐dimethylmethanamine (BPDMA) as optimal component modifier. Comprehensive analyses disclose the unique electrochemically‐active Br‐containing ion‐pairs formation, such as [(Mg2+)2(TFSI−)Br−]2+ and [(Mg2+)2(TFSI−)(Br−)(G2)2]2+, which results in the much thinner Br− containing and organic–inorganic mixed interphases on Mg‐metal anodes. Furthermore, conventional MgSO4‐based electrolytes and even calcium (Ca)‐ion electrolytes can also be revived by similar strategy, demonstrating its generality and superiority.

Reviving Multivalent-Metal Anodes in Simple Salt Electrolytes via Component Modifier Design.

Using combinatory electrolyte blends represents an imperative avenue to achieve good magnesium (Mg)-metal anode compatibility and commercial feasibility in fields of promising rechargeable Mg batteries. However, fundamental challenges of how to manipulate component modifier reactivity on molecule level still remain to be solved. Here, molecular structure design concepts towards seeking bromophenyl complex-based component modifiers has been proposed according to implications of electron-donating and/or electron-withdrawing substituents on Br-C bond dissociation reactivity. Exceptional Mg electro-plating/stripping properties (a stable cycle life of 250 days in Mg//Cu asymmetric cells) have been firstly achieved in a simple salt electrolyte with 1-(3-bromophenyl)-N,N-dimethylmethanamine (BPDMA) as optimal component modifier. Comprehensive analyses disclose the unique electrochemically-active Br-containing ion-pairs formation, such as [(Mg2+)2(TFSI-)Br-]2+ and [(Mg2+)2(TFSI-)(Br-)(G2)2]2+, which results in the much thinner Br- containing and organic-inorganic mixed interphases on Mg-metal anodes. Furthermore, conventional MgSO4-based electrolytes and even calcium (Ca)-ion electrolytes can also be revived by similar strategy, demonstrating its generality and superiority.

Design of Thermally Activated Delayed Fluorescence Materials: Transition from Carbonyl to Amide‐Based Acceptor

AbstractBenzophenone skeletons containing a carbonyl unit (O=C) have been widely used as electron acceptors in the thermally activated delayed fluorescence (TADF) materials. Herein, we present a novel molecular design concept for TADF materials by transitioning from a carbonyl to an amide (O=C−N) skeleton as the acceptor. The amide unit, compared to its carbonyl counterpart, offers a more stable electronic configuration. Leveraging this insight, we have developed a series of high‐performance TADF molecules based on benzoyl carbazole and carbazoline acceptors. These molecules exhibit exceptionally small singlet‐triplet energy gaps and pronounced aggregation‐enhanced emission properties, achieving photoluminescence quantum yields in neat films as high as 99 %. Consequently, these materials serve as efficient emitters in non‐doped organic light‐eimtting diodes (OLEDs), reaching a maximum quantum efficiency (EQEmax) of up to 26.0 %, significantly higher than the 17.0 % obtained with benzophenone acceptor‐based TADF molecules. Additionally, they have been used as TADF hosts in narrowband red fluorescent OLEDs, setting a record‐high EQEmax of 22.4 %.

ChatMol: interactive molecular discovery with natural language.

Natural language is poised to become a key medium for human-machine interactions in the era of large language models. In the field of biochemistry, tasks such as property prediction and molecule mining are critically important yet technically challenging. Bridging molecular expressions in natural language and chemical language can significantly enhance the interpretability and ease of these tasks. Moreover, it can integrate chemical knowledge from various sources, leading to a deeper understanding of molecules. Recognizing these advantages, we introduce the concept of conversational molecular design, a novel task that utilizes natural language to describe and edit target molecules. To better accomplish this task, we develop ChatMol, a knowledgeable and versatile generative pretrained model. This model is enhanced by incorporating experimental property information, molecular spatial knowledge, and the associations between natural and chemical languages. Several typical solutions including large language models (e.g. ChatGPT) are evaluated, proving the challenge of conversational molecular design and the effectiveness of our knowledge enhancement approach. Case observations and analysis offer insights and directions for further exploration of natural-language interaction in molecular discovery. Codes and data are provided in https://github.com/Ellenzzn/ChatMol/tree/main.

Design of Thermally Activated Delayed Fluorescence Materials: Transition from Carbonyl to Amide-Based Acceptor.

Benzophenone skeletons containing a carbonyl unit (O=C) have been widely used as electron acceptors in the thermally activated delayed fluorescence (TADF) materials. Herein, we present a novel molecular design concept for TADF materials by transitioning from a carbonyl to an amide (O=C-N) skeleton as the acceptor. The amide unit, compared to its carbonyl counterpart, offers a more stable electronic configuration. Leveraging this insight, we have developed a series of high-performance TADF molecules based on benzoyl carbazole and carbazoline acceptors. These molecules exhibit exceptionally small singlet-triplet energy gaps and pronounced aggregation-enhanced emission properties, achieving photoluminescence quantum yields in neat films as high as 99 %. Consequently, these materials serve as efficient emitters in non-doped organic light-eimtting diodes (OLEDs), reaching a maximum quantum efficiency (EQEmax) of up to 26.0 %, significantly higher than the 17.0 % obtained with benzophenone acceptor-based TADF molecules. Additionally, they have been used as TADF hosts in narrowband red fluorescent OLEDs, setting a record-high EQEmax of 22.4 %.

The Development of Quinoxaline-Based Electron Acceptors for High Performance Organic Solar Cells.

In the recent advances of organic solar cells (OSCs), quinoxaline (Qx)-based nonfullerene acceptors (QxNFAs) have attracted lots of attention and enabled the recorded power conversion efficiency approaching 20%. As an excellent electron-withdrawing unit, Qx possesses advantages of many modifiable sites, wide absorption range, low reorganization energy, and so on. To develop promising QxNFAs to further enhance the photovoltaic performance of OSCs, it is necessary to systematically summarize the QxNFAs reported so far. In this review, all the focused QxNFAs are classified into five categories as following: SM-Qx, YQx, fused-YQx, giant-YQx, and polymer-Qx according to the molecular skeletons. The molecular design concepts, relationships between the molecular structure and optoelectronic properties, intrinsic mechanisms of device performance are discussed in detail. At the end, the advantages of this kind of materials are summed up, the molecular develop direction is prospected, the challenges faced by QxNFAs are given, and constructive solutions to the existing problems are advised. Overall, this review presents unique viewpoints to conquer the challenge of QxNFAs and thus boost OSCs development further toward commercial applications.

Lattice Symmetry-Guided Charge Transport in 2D Supramolecular Polymers Promotes Triplet Formation.

Singlet-to-triplet intersystem crossing (ISC) in organic molecules is intimately connected with their geometries: by modifying the molecular shape, symmetry selection rules pertaining to spin-orbit coupling can be partially relieved, leading to extra matrix elements for increased ISC. As an analog to this molecular design concept, the study finds that the lattice symmetry of supramolecular polymers also defines their triplet formation efficiencies. A supramolecular polymer self-assembled from weakly interacting molecules is considered. Its 2D oblique unit cell effectively renders it as a coplanar array of 1D molecular columns weakly bound to each other. Using momentum-resolved photoluminescence imaging in combination with Monte Carlo simulations, the study found that photogenerated charge carriers in the supramolecular polymer predominantly recombine as spin-uncorrelated carrier pairs through inter-column charge transfer states. This lattice-defined recombination pathway leads to a substantial triplet formation efficiency (≈60%) in the supramolecular polymer. These findings suggest that lattice symmetry of micro-/macroscopic structures relying on intermolecular interactions can be strategized for controlled triplet formation.

Anticancer Therapy with Proteolysis-targeting Chimeras [PROTACs] Targeting Towards the Tumor-microenvironment: Development, Current State and Prospects

Abstract: Targeted protein degradation is a rapidly expanding area that offers hope for novel approaches to combat drug resistance. The creation of heterobifunctional proteolysis-targeting chimeras [PROTACs], a new group of pharmaceutical compounds, has made TPD a useful method for completely getting rid of harmful proteins using regular small-molecule inhibitors. A big plus is that PROTACs can target multi-domain proteins that cannot be broken down. This is the case, particularly for proteins lacking a conserved interaction surface for small-molecule ligands [SMIs] and featuring smooth surfaces. Poor oral bioavailability and pharmacokinetic [PK] and ADMET [absorption, distribution, metabolism, excretion, and toxicity] characteristics are among the long-term issues with traditional PROTACs. Their larger size and more complex structure set them apart from other smallmolecule inhibitors, which is why they are so effective. Clinical studies have been conducted on a plethora of PROTAC compounds in the past 20 years, all with the goal of inducing the degradation of targets relevant to cancer. In this article, we closely examine the major developments and recent advancements in PROTAC technology. We seek to summarize and fully assess PROTAC-based targeted protein degradation studies on "undruggable" targets. Discussing their molecular structure, action mechanism, design concepts, development benefits, and obstacles will help to illustrate the significance of developing highly successful PROTAC-based techniques in treating many illnesses, including cancer treatment resistance.

An ER-targeted, Viscosity-sensitive Hemicyanine Dye for the Diagnosis of Nonalcoholic Fatty Liver and Photodynamic Cancer Therapy by Activating Pyroptosis Pathway.

The concept of molecular design, integrating diagnostic and therapeutic functions, aligns with the general trend of modern medical advancement. Herein, we rationally designed the smart molecule ER-ZS for endoplasmic reticulum (ER)-targeted diagnosis and treatment in cell and animal models by combining hemicyanine dyes with ER-targeted functional groups (p-toluenesulfonamide). Owing to its ability to target the ER with a highly specific response to viscosity, ER-ZS demonstrated substantial fluorescence turn-on only after binding to the ER, independent of other physiological environments. In addition, ER-ZS, being a small molecule, allows for the diagnosis of nonalcoholic fatty liver disease (NAFLD) via liver imaging based on high ER stress. Importantly, ER-ZS is a type I photosensitizer, producing O2 ⋅- and ⋅OH under light irradiation. Thus, after irradiating for a certain period, the photodynamic therapy inflicted severe oxidative damage to the ER of tumor cells in hypoxic (2 % O2 ) conditions and activated the unique pyroptosis pathway, demonstrating excellent antitumor capacity in xenograft tumor models. Hence, the proposed strategy will likely shed new light on integrating molecular optics for NAFLD diagnosis and cancer therapy.

An ER‐targeted, Viscosity‐sensitive Hemicyanine Dye for the Diagnosis of Nonalcoholic Fatty Liver and Photodynamic Cancer Therapy by Activating Pyroptosis Pathway

AbstractThe concept of molecular design, integrating diagnostic and therapeutic functions, aligns with the general trend of modern medical advancement. Herein, we rationally designed the smart molecule ER‐ZS for endoplasmic reticulum (ER)‐targeted diagnosis and treatment in cell and animal models by combining hemicyanine dyes with ER‐targeted functional groups (p‐toluenesulfonamide). Owing to its ability to target the ER with a highly specific response to viscosity, ER‐ZS demonstrated substantial fluorescence turn‐on only after binding to the ER, independent of other physiological environments. In addition, ER‐ZS, being a small molecule, allows for the diagnosis of nonalcoholic fatty liver disease (NAFLD) via liver imaging based on high ER stress. Importantly, ER‐ZS is a type I photosensitizer, producing O2⋅− and ⋅OH under light irradiation. Thus, after irradiating for a certain period, the photodynamic therapy inflicted severe oxidative damage to the ER of tumor cells in hypoxic (2 % O2) conditions and activated the unique pyroptosis pathway, demonstrating excellent antitumor capacity in xenograft tumor models. Hence, the proposed strategy will likely shed new light on integrating molecular optics for NAFLD diagnosis and cancer therapy.

Frontier Molecular Orbital Engineering of Aromatic Donor Fusion: Modularly Constructing Highly Efficient Narrowband Yellow Electroluminescence.

The development of high-performance multiple resonance thermally activated delayed fluorescence (MR-TADF) materials with narrowband yellow emission is highly critical for various applications in industries, such as the automotive, aerospace, and microelectronic industries. However, the modular construction approaches to expeditiously access narrowband yellow-emitting materials is relatively rare. Here, a unique molecular design concept based on frontier molecular orbital engineering (FMOE) of aromatic donor fusion is proposed to strategically address this issue. Donor fusion is a modular approach with a "leveraging effect"; through direct polycyclization of donor attached to the MR parent core, it is facile to achieve red-shifted emission by a large margin. As a result, two representative model molecules, namely BN-Cz and BN-Cb, have been constructed successfully. The BN-Cz- and BN-Cb-based sensitized organic light-emitting diodes (OLEDs) exhibit bright yellow emission with peaks of 560 and 556 nm, full-width at half-maxima (fwhm's) of 49 and 45 nm, Commission Internationale de L'Eclairage coordinates of (0.44, 0.55) and (0.43, 0.56), and maximum external quantum efficiencies (EQEs) of 32.9% and 29.7%, respectively. The excellent optoelectronic performances render BN-Cz and BN-Cb one of the most outstanding yellow-emitting MR-TADF materials.

Achieving pure room temperature phosphorescence (RTP) in phenoselenazine-based organic emitters through synergism among heavy atom effect, enhanced n → π* transitions and magnified electron coupling by the A-D-A molecular configuration.

The weak spin-orbit coupling (SOC) in metal-free organic molecules poses a challenge in achieving phosphorescence emission. To attain pure phosphorescence in RTP organic emitters, a promising molecular design concept has been proposed. This involves incorporating n → π* transitions and leveraging the heavy atomic effect within the spin-orbit charge transfer-induced intersystem crossing (SOCT-ISC) mechanism of bipolar molecules. Following this design concept, two bipolar metal-free organic molecules (PhSeB and PhSeDB) with donor-acceptor (D-A) and acceptor-donor-acceptor (A-D-A) configurations have been synthesized. When the molecular configuration changes from D-A to A-D-A, PhSeDB exhibits stronger electron coupling and n → π* transitions, which can further enhance the spin-orbit coupling (SOC) together with the heave atom effect from the selenium atom. By the advanced synergism among enhanced n → π* transitions, heavy atom effect and magnified electron coupling to efficiently promote phosphorescence emission, PhSeDB can achieve pure RTP emission in both the solution and doped solid film. Thanks to the higher spin-orbit coupling matrix elements (SOCMEs) for T1 ↔ S0, PhSeDB attains the highest phosphorescence quantum yield (ca. 0.78) among all the RTP organic emitters reported. Consequently, the purely organic phosphorescent light-emitting diodes (POPLEDs) based on PhSeDB achieve the highest external quantum efficiencies of 18.2% and luminance of 3000 cd m-2. These encouraging results underscore the significant potential of this innovative molecular design concept for highly efficient POPLEDs.

Development of Dual-Functional Polyamide Imidazole Binder for Silicon Anode Lithium-Ion Battery

Silicon (Si) is one of the most promising anode materials in lithium-ion batteries (LIBs). However, Si undergoes a huge volume change during charging/discharging and induces intractable problems such as delamination, cracking of electrode, and unstable solid electrolyte interphase. Polymer binder is one of powerful strategies to prevent the problem. In this study, the novel polyamide imidazole (PAID) binder is synthesized and forms imide and imidazole intermediate phase (i-PAID) at electrode fabrication temperature. The i-PAID binder have strong interaction with Si particle and carbon black by ambidextrous binding effect. Introduction of amine and carboxylic acid in i-PAID binder enhances adhesion force of the Si particles. In addition, the extended polymer backbone of i-PAID improves not only inter-molecular interaction with carbon black by π-π stacking interaction but also sustains robust conduction pathway in Si anode. The Si anode with i-PAID binder confirmed outstanding mechanical durability of Si during charging/discharging through in-situ electrochemical dilatometer and ex-situ SEM observation. It exhibited higher reversible capacity and stable cycle performance for 200 cycles at 0.2C than the Si anode with commercial polyimide binder, respectively. Thus, the ambidextrous polymer binder would propose new molecular design concept for Si anode in LIBs.

Nerve Visualization using Phenoxazine-Based Near-Infrared Fluorophores to Guide Prostatectomy.

Fluorescence-guided surgery (FGS) is poised to revolutionize surgical medicine through near-infrared (NIR) fluorophores for tissue- and disease-specific contrast. Clinical open and laparoscopic FGS vision systems operate nearly exclusively at NIR wavelengths. However, tissue-specific NIR contrast agents compatible with clinically available imaging systems are lacking, leaving nerve tissue identification during prostatectomy a persistent challenge. Here, it is shown that combining drug-like molecular design concepts and fluorophore chemistry enabled the production of a library of NIR phenoxazine-based fluorophores for intraoperative nerve-specific imaging. The lead candidate readily delineated prostatic nerves in the canine and iliac plexus in the swine using the clinical da Vinci Surgical System that has been popularized for minimally invasive prostatectomy procedures. These results demonstrate the feasibility of molecular engineering of NIR nerve-binding fluorophores for ready integration into the existing surgical workflow, paving the path for clinical translation to reduce morbidity from nerve injury for prostate cancer patients.

Dynamic Thermostable Cellulosic Triboelectric Materials from Multilevel-Non-Covalent Interactions.

Triboelectric materials present great potential for harvesting huge amounts of dispersed energy, and converting them directly into useful electricity, a process that generates power more sustainably. Triboelectric nanogenerators (TENGs) have emerged as a technology to power electronics and sensors, and it is expected to solve the problem of energy harvesting and self-powered sensing from extreme environments. In this paper, a high-temperature-resistant triboelectric material is designed based on multilevel non-covalent bonding interactions, which achieves an ultra-high surface charge density of 192 µC m-2 at high temperatures. TENGs based on the triboelectric material exhibit more than an order of magnitude higher power output (2750mW m-2 at 200°C) than the existing devices at high temperatures. These remarkable properties are achieved based on enthalpy-driven molecular assembly in highly unbonded states. Thus, the material maintains bond strength and ultra-high surface charge density in entropy-dominated high-temperature environments. This molecular design concept points out a promising direction for the preparation of polymers with excellent triboelectric properties.

Molecular Design Concept for Enhancement Charge Carrier Mobility in OFETs: A Review.

In the last two decades, organic field-effect transistors (OFETs) have garnered increasing attention from the scientific and industrial communities. The performance of OFETs can be evaluated based on three factors: the charge transport mobility (μ), threshold voltage (Vth), and current on/off ratio (Ion/off). To enhance μ, numerous studies have concentrated on optimizing charge transport within the semiconductor layer. These efforts include: (i) extending π-conjugation, enhancing molecular planarity, and optimizing donor-acceptor structures to improve charge transport within individual molecules; and (ii) promoting strong aggregation, achieving well-ordered structures, and reducing molecular distances to enhance charge transport between molecules. In order to obtain a high charge transport mobility, the charge injection from the electrodes into the semiconductor layer is also important. Since a suitable frontier molecular orbitals' level could align with the work function of the electrodes, in turn forming an Ohmic contact at the interface. OFETs are classified into p-type (hole transport), n-type (electron transport), and ambipolar-type (both hole and electron transport) based on their charge transport characteristics. As of now, the majority of reported conjugated materials are of the p-type semiconductor category, with research on n-type or ambipolar conjugated materials lagging significantly behind. This review introduces the molecular design concept for enhancing charge carrier mobility, addressing both within the semiconductor layer and charge injection aspects. Additionally, the process of designing or converting the semiconductor type is summarized. Lastly, this review discusses potential trends in evolution and challenges and provides an outlook; the ultimate objective is to outline a theoretical framework for designing high-performance organic semiconductors that can advance the development of OFET applications.

Tunable Conformal Electrodeposition of Ultra-Thin Polymeric Films for Electrolyte Interphases

Functional coatings and interphases influence the stability and performance parameters of electrodes in various applications. Polymer thin films offer a wide range of molecular structures and compositions for tunable functionalities that can be custom designed to the needs of an application. In solid-state energy storage devices in particular, electrolyte-type polymeric interfaces between battery components and materials with disparate functions, such as the active electrode material and solid electrolyte could overcome some of these incompatibility detriments and the increase in contact resistance over long-term operation. In high-performance micro scale power sources, 3D thin-film all-solid-state batteries show great potential as they take advantage of both short ion diffusion distances for high-rate capability with low heat generation, as well as the third dimension for high material loading and energy density. Therefore, conformal deposition methods for ultra-thin polymeric electrolyte interphases on the interior surface of electrodes with mesoscale 3D architectures and complex porosity are in demand. Here, we report a molecular design concept of dual-functional molecules that contain electrochemically active end groups for self-limiting electropolymerization, and a core molecular motif that determines the thin film functionality. The electrodeposition of this monomer represents a non-line-of-sight coating method for polymer thin films with independently tailorable functionalities and tunable properties on conductive substrates with arbitrary shape. We exemplify this method using monomers with poly(ethylene glycol) (PEG) as the core motif for lithium-ion transport and phenol as electrochemically active end groups. We studied the electrodeposition of the monomers, poly(ethylene glycol) diphenol (PEGDP), and demonstrate their self-limiting film formation mechanism (Figure 1a) which originates from the insulating nature of resulting poly(PEGDP) film that confines the charge transfer reaction. We present an exhaustive exploration of their material-processing-structure-property relationships that reveals the multi-scale control over the ultrathin-film properties. For example, the uniform film thickness is tunable from 10 to 100s of nanometer through electrodeposition conditions and molecular design, while their molecular permeability and electronic resistance can be tailored from pervious to fully blocking. We show that the electrodeposited functional interphases fully coat complex 3D electrode architectures (Figure 1b top: uncoated carbon electrode, bottom: film coated carbon electrode) with retention of their functionality in a battery. This work demonstrates that rational molecular design enables the conformal electrodeposition of ultrathin functional coatings with solid polymer electrolyte properties on 3D structured electrodes that will enable designer interphases in various solid-state battery architectures and chemistries. Figure 1

Collective bending motion of a two-dimensionally correlated bowl-stacked columnar liquid crystalline assembly under a shear force.

Stacked teacups inspired the idea that columnar assemblies of stacked bowl-shaped molecules may exhibit a unique dynamic behavior, unlike usual assemblies of planar disc- and rod-shaped molecules. On the basis of the molecular design concept for creating higher-order discotic liquid crystals, found in our group, we synthesized a sumanene derivative with octyloxycarbonyl side chains. This molecule forms an ordered hexagonal columnar mesophase, but unexpectedly, the columnar assembly is very soft, similar to sugar syrup. It displays, upon application of a shear force on solid substrates, a flexible bending motion with continuous angle variations of bowl-stacked columns while preserving the two-dimensional hexagonal order. In general, alignment control of higher-order liquid crystals is difficult to achieve due to their high viscosity. The present system that brings together higher structural order and mechanical softness will spark interest in bowl-shaped molecules as a component for developing higher-order liquid crystals with unique mechanical and stimuli-responsive properties.

Towards high-performance anthraquinone-derived cathode material for lithium-ion batteries through rational molecular design

Organic electrode materials are considered to be one of promising alternatives for next-generation lithium-ion batteries, yet they often suffer from problem of severe dissolution in electrolytes, which inhibits their practicability. Herein, a rational molecular design strategy through constructing redox-active molecules with non-fused ring but planar structure was proposed. To validate our ideas, 1,4-bis(9,10-anthraquinonyl)pyrazine (BAQP) was synthesized by connecting two AQ units to 2,5-positions of pyrazine via C-C bond. Density functional theory calculation reveals that BAQP is a planar structure because of reduction of hydrogen atoms adjacent to bonding sites. Comparative experiments show that solubility of BAQP is significantly reduced. Electrochemical tests demonstrate BAQP electrode for lithium-ion batteries displays prominently enhanced cycle performance (90.7% retention after 100 cycles at 0.2 C) and rate capability (capacity at 5 C is 79.8% of capacity at 0.2 C), which is much better than that of its control molecule, 1,4-bis(9,10-anthraquinonyl)benzene (BAQB, corresponding retentions are 40.2% and 53.5%, respectively). Importantly, the BAQP electrode also shows an excellent long cycle life of 1000 cycle with high retention of 70.0%, which is among the best long-term cycle performance in the literature about AQ-derived small molecule electrode materials. These results manifest that the molecular design concept of fabricating non-fused ring but planar structure is effective to develop high-performance organic electrode materials.

Harnessing the Structure-Performance Relationships in Designing Non-Fused Ring Acceptors for Organic Solar Cells.

The prerequisite for commercially viable organic solar cells (OSC) is to reduce the efficiency-stability-cost gap. Therefore, the cost of organic materials should be reduced by minimizing the synthetic steps, yet maintaining the molecular planarity and efficiencies achieved by the fused ring acceptors (FRA). In this respect, developing non-fused ring acceptors (NFRA) with suitable functionalization to favor conformational planarity and effective molecular packing is beneficial and cost-effective. Presently, the power conversion efficiency (PCE) for NFRAs is around 16 %, yet lower than the 19 % achieved for FRAs. Despite their potential, a thorough understanding of the effective structural design of NFRAs is necessary for developing efficient OSCs. This article pays special attention to the molecular design concept for NFRAs developed in the last years and analyzed the approach toward materials design and efficiency improvement, an important step toward technological application.