LUMO Energy Levels Research Articles

The Effect of Organic Semiconductor Electron Affinity on Preventing Parasitic Oxidation Reactions Limiting Performance of n-Type Organic Electrochemical Transistors.

A key challenge in the development of organic mixed ionic-electronic conducting materials (OMIEC) for high performance electrochemical transistors is their stable performance in ambient. When operating in aqueous electrolyte, potential reactions of the electrochemically injected electrons with air and water could hinder their persistence, leading to a reduction in charge transport. Here, the impact of deepening the LUMO energy level of a series of electron-transporting semiconducting polymers is evaluated, and subsequently rendering the most common oxidation processes of electron polarons thermodynamically unfavorable, on organic electrochemical transistors (OECTs) performance. Employing time resolved spectroelectrochemistry with three analogous polymers having varying electron affinities (EA), it is found that an EA below the thermodynamic threshold for oxidation of its electron polarons by oxygen significantly improves electron transport and lifetime in air. A polymer with a sufficiently large EA and subsequent thermodynamically unfavorable oxidation of electron polarons is reported, which is used as the semiconducting layer in an OECT, in its neutral and N-DMBI doped form, resulting in an excellent and air-stable OECT performance. These results show a general design methodology to avoid detrimental parasitic reactions under ambient conditions, and the benefits that arise in electrical performance.

Charge Transfer‐Induced SERS Enhancement of MoS2/Dopants Dependent on their Interaction Difference

Abstract2D transition metal dichalcogenide materials have attracted increasing attention as active surface‐enhanced Raman spectroscopy (SERS) platforms. In this study, the influence of n‐ and p‐type doping of exfoliated MoS2 (exMoS2) hybrids on the SERS performance is investigated, employing Rhodamine 6G (R6G) as a probe molecule. It is demonstrated that n‐doped exMoS2 hybrids (exMoS2 mixed with C60, graphene, and sodium dodecyl sulfate) exhibit enhanced SERS intensities, while p‐doping (exMoS2 mixed with TCNQ) resulted in inhibited SERS enhancement. A key discovery is the linear relationship between Raman enhancement of MoS2/dopant hybrids and the difference in their LUMO energy levels, which dictate the degree and direction of charge transfer. Interestingly, MC60‐4, a C60‐doped hybrid, deviates from the linear relationship, displaying remarkable SERS enhancement owing to its chemical interaction and unique Raman scattering activity. The findings provide critical insights into the SERS enhancement behavior of doped MoS2, facilitating precise tuning of SERS intensities by manipulating the MoS2 doping state.

Theoretical exploration of the photophysical properties of two series of iridium(III) complexes with different main ligand

On the basis of the thiophene-containing and furan-containing complexes, we design four complexes by introducing thiazole, isothiazole, oxazole, isoxazole on main ligands. The electronic structure, absorption and emission spectra, charge injection/transport properties, absorption and phosphorescence properties have been investigated by density functional theory (DFT) and time-dependent density functional theory (TDDFT). Introducing S atom to substitute O atom could enhance HOMO energy level, blueshift emission wavelength, decrease ΔES1- T1 value. The introduction of N atom on furan ring and thiophene ring could decrease HOMO and LUMO energy levels and energy gaps, blueshift emission wavelength, decrease ΔES1- T1 value, enhance electron transport ability. Introducing thiazole could decrease hole injection ability and ΔES1- T1, and then may have higher ΦPL. Isoxazole and isothiazole groups could facilitate the electron transition from HOMO to LUMO and enhance hole injection ability. Thiazole and isothiazole groups could increase absorption peak strength and hole transport ability.

Novel low‐band gap non‐fullerene acceptors based on IDIC core as potential photovoltaic materials

AbstractThree novel non‐fullerene acceptors (NFAs) (PhBu‐IDT‐BT‐IC, PhBu‐IDT‐BT‐IC4F and PhBu‐IDT‐BT‐IC4Cl) based on 3,8‐dioctyl‐indaceno[1,2‐b:5,6‐b’]dithiophene (IDT) core have been designed and synthesized with and without halogen (F and Cl) substitution. The NFAs showed high thermal stability. The ultraviolet–visible absorption studies in solution and thin film for the three acceptors revealed maximum absorption from 687 to 732 nm and 731 to 847 nm, respectively. The onset of absorption in the thin film was found to be extending up to around 960 nm for PhBu‐IDT‐BT‐IC4Cl. The optical band gap ranged from 1.30 to 1.41 eV, which are very low and useful for photovoltaic application. The introduction of halogen appreciably altered the LUMO energy levels, whereas the HOMO energy levels were nearly intact. These small molecule non‐fullerene acceptors could be used as potential acceptors in bulk heterojunction organic photovoltaic (BHJ‐OPV) applications.

Tunable optoelectronic performances of aminated benzothiadiazole-based D-A-D conjugated electrochromic polymers

Introducing heteroatom groups into benzothiadiazole (BT) unit has proven to be a very effective way to improve the optoelectronic properties of conjugate polymer due to its comprehensive advantages of lowering the HOMO or LUMO energy level, and increasing the interaction force on the polymer backbone. However, at present, little attention was paid to introducing amino groups into the BT unit. Herein, in this work, three D-A-D type aminated monomers (Th–NH2-BT, Th–2NH2-BT, and EDOT-2NH2-BT) with aminated benzothiadiazole as the acceptor unit and thiophene or 3,4-ethylenedioxythiophene (EDOT) as the donor unit were successfully synthesized by Stille coupling reaction, and their corresponding aminated polymers (P(Th–NH2-BT), P(Th–2NH2-BT), and P(EDOT-2NH2-BT)) were facilely achieved by electrochemical polymerization method. The optoelectronic properties of the aminated monomers and their D-A polymers were carefully analyzed, and the electrochemical and electrochromic properties of the resultant aminated polymers were further studied. The finally results show that the absorption and fluorescence spectra of Th–2NH2-BT and EDOT-2NH2-BT are both blue-shifted compared to Th–NH2-BT, and the corresponding optical bandgap are gradually increased (2.41 eV–2.65 eV). EDOT-2NH2-BT has a relatively lower oxidation potential (0.73 V) and P(EDOT-2NH2-BT) also has a wide potential window and better redox stability, which was very beneficial for improving its resultant D-A aminated polymers’ optoelectronic properties. As a result, as-formed P(EDOT-2NH2-BT) shown obvious color change from green in the neutral state to gray in the oxidized state with favorable electrochromic performances, with a high optical contrast (ΔT = 17.17 % at 860 nm) and high coloration efficiency (CE = 223 C−1 cm2 at 860 nm), so it is one of the promising materials that can be used in electrochromic devices.

Synthesis, enantiomeric separation and (chir)optical properties of [7]helicene derivatives for OLED applications. A comprehensive experimental and computational investigation

A two–step photochemical process was employed to synthesize new racemic [7]helicenes with appropriate functional groups, resulting in an overall yield of 61 % to 74 %. These helical species showed good solubility in common solvents and confirmed structurally through various spectroscopic methods. In solution, they exhibited strong absorption (λabs = 250–500 nm) and blue light emission with a fluorescence quantum yield (Φ) ranging from 7 % to 26 %. Experimental analysis of their HOMO and LUMO energy levels highlighted an irreversible electrochemical behavior and a band gap (Eg–el) of 2.60 eV to 2.64 eV. The helicenes were successfully separated by chiral HPLC, yielding P and M–enantiomers in high optical purity (>98.5 % up to >99.5 % ee) that demonstrated substantial optical rotations (e.g., +3700–5000 for the P–enantiomer at λ = 589 nm) and notable electronic circular dichroism (ECD) signals. Density functional theory (DFT) was undertaken to establish connections between diverse structure-properties relationships and precisely replicate the experimental findings. Ultimately, these helical species, with notable performance in emission, electrochemical behavior, and thermal stability, can effectively serve as blue-emitting chiral dopants in OLED devices and as hole-transport units.

Disulfide bonded polyimide cathode of rechargeable magnesium batteries: Improved capacity via reversible break/formation of disulfide and sulfur-oxygen bonds

Rechargeable magnesium batteries are a potential selection for large-scale energy storage technologies, but development of cathode materials is the major difficulty at present. Organic polyimides are promising magnesium battery cathodes with the open and amorphous frameworks as well as enhanced charge delocalization. However, only two carbonyls are redox-active out of four for each imide unit, which largely limits the capacity. Herein, a new polyimide containing disulfide bond is fabricated and studied as cathode for rechargeable magnesium batteries. This polyimide shows a high capacity beyond the traditional two-electron principle. A mechanism study demonstrates that carbonyl enolization and disulfide bond break/formation occur in the redox process, leading to formation/break of sulfur-oxygen bond. This sulfur-oxygen bond enhances enolization and electron delocalization, resulting in an improved capacity. Further theoretical computation indicates a charge transfer within this sulfur-oxygen bond. The two-electron reduction state exhibits quite low HOMO and LUMO energy levels, which makes the disulfide bonded polyimide have a higher tendency to accept more electrons and a higher oxidation stability after reduction.

Elucidating roles of fulleropyrrolidine-based materials as extraordinary electron transporters for boosting efficiency of perovskite photovoltaics

To achieve an ideal electron transfer layer (ETL) for perovskite solar cell (PSC), effective compounds were developed based on fullerene C60 functionalized with a pyrrolidine ring (fulleropyrrolidine), to which a cyanoethyl group, a thiophene ring, and four DNA bases were attached. Density functional theory (DFT) calculations were employed to study structural, electronic, optical, and electron mobility features of these materials. To more precisely determine the HOMO and LUMO energy levels of all samples, the NBO calculations were accomplished at PBE0-D3/6-31G(d,p) theoretical level. The LUMO levels of all ETL samples could be aligned with the conduction band of perovskite CsFAMAPbIBr via their coupling within fabricated PSCs, enabling easy electron injection from CsFAMAPbIBr to the Ag electrode. All functionalized fullerene C60–based ETLs exhibited very high electron mobilities in the range of 0.744–1.598 cm2V−1s−1 which were significantly greater than 1.461 × 10−5 cm2V−1s−1 for pure C60 as the reference. High fill factors (FFs), power conversion efficiencies (PCEs), and open circuit voltages (VOC) were measured for PSC devices with C60–based ETLs, varying within the ranges of 0.892–0.897, 22.489–23.984 %, and 1.111–1.179 V, respectively, indicating they could yield excellent photovoltaic parameters.

Theoretical Investigation of Transport Properties of X-doped (X = Cl, P, N) Graphene Quantum Dots Layer Adsorbed with Ammonia Molecule Using Non-Equilibrium Green’s Function

This study investigates the various transport properties, including Density of States (DOS), Transmission Coefficient, Current-Voltage Characteristics (I-V), and HOMO-LUMO energy levels, of X-doped (X = Cl, P, N) graphene quantum dot (GQD) layers with adsorbed ammonia molecules using density functional theory and non-equilibrium Green's function techniques. Our findings revealed the profound influence of different doping and adsorption scenarios on the transport properties of GQD layers. Specifically, chlorine doping leads to notably stronger resonance peaks, resulting in enhanced conductivity of the GQD layer. This effect is less pronounced for P-doped and N-doped GQDs, which exhibit minimal changes in conductance capability. Importantly, we observed a prominent interaction between ammonia molecules and chlorine-doped GQD layers. The HOMO and LUMO energy levels exhibit double degeneracy, significantly impacting edge passivation and the finite dimensions of GQDs, consequently reducing the energy gap. As a result, chlorine-doped GQD layers with adsorbed ammonia molecules exhibit increased energy levels and stronger current characteristics compared to P-GQDs and N-GQDs. HOMO and LUMO are doubly degenerated which has a clear effect on edge passivation as well as the finite size of GQDs and reduces energy gap. Therefore, more energy level and stronger current is available for chlorine doped graphene quantum dots layer with adsorbed ammonia molecule than P-GQDs and N-GQDs. Our theoretical finding highlighted the significant features of edge passivation, doping effect and adsorption of ammonia molecule onto graphene quantum dots layer. Our theoretical analysis highlighted key features encompassing edge passivation, doping effects, and ammonia molecule adsorption on GQD layers. These insights not only develop our fundamental understanding of these systems but also hold promise for novel applications that harness their distinct electronic properties.

Exploring the electronic structure of tetrathienylethene derivatives for OLED applications: A theoretical study

AbstractThe B3LYP/6‐31G(d,p) method is applied to investigate the structural and electronic properties of tetrathienylethene (TTE) derivatives, specifically for the properties of 14 distinct TTE derivatives. The results indicate that the T1–T14 derivatives exhibit numerous advantages over the parent TTE compound. Notably, substituents predominantly impact the LUMO energy level of the TTE parent compound. Additionally, all modified molecules exhibit lower energy band gaps (Egap) and improved charge transfer capacity relative to TTE. These findings suggest that the T1–T14 derivatives may be promising candidates for use as materials in OLED applications. The values of chemical hardness (η) indicate that all compounds T1–T14 manifest greater softness relative to the parent compound TTE. This correlation aligns with the calculated Egap values, wherein compounds T1–T14 consistently exhibit smaller Egap values compared to the TTE compound. These research findings indicate that compounds T1 and T10 display remarkable and harmonious charge transfer capabilities. This is evident from their corresponding values of λh and λe, which stand at 0.39/0.41 and 0.41/0.41 eV, respectively. Remarkably, compound T1 exhibits the most pronounced absorption peak, occurring at a wavelength of 441 nm. This absorption is accompanied by the highest oscillator strength recorded for the compound, reaching a value of 0.638.

Synthesis of conjugated structural copolymer poly(3-hexylthiophene-random-benzoyl dithieno[3,2-b:2’,3’-d]pyrrole) by electrochemical method

Electrochemical copolymer synthesis of benzoyl dithieno[3,2-b:2’,3’-d]pyrrole and 3-hexylthiophene (3HT) promises to create new polymer with suitable improved HOMO and LUMO with the energy level of acceptor compounds such as Fullerene (C60) or the novel accepted organic compound in the heterojunction in organic solar cell. Electrochemical synthesis of copolymer (3-hexylthiophene-random-benzoylbdithieno[3,2-b:2’,3’-d]pyrrole by linear potential scanning method was studied and applied for synthesis of conjugated copolymer where three electrodes have been used for polymerisation including the working electrode of Indium Tin Oxide (ITO) substrate, the reference electrode of Ag/AgCl in saturated KCl and the counter electrode of platinum wire. The synthesised copolymer was characterised and evaluated through an electrochemical process, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and ultraviolet-visible spectroscopy (UV-Vis) measurements. The synthesised copolymer has a bandgap of 2.09 eV, HOMO and LUMO energy levels of -5.21 and -3.12 eV, respectively. The HOMO-LUMO of the synthesised conjugated copolymer is closed with the HOMO-LUMO of Fullerene; therefore, the conjugated copolymer is a potential material for the fabrication of organic solar cell.

Fluorescent ‘turn-on’ porphyrin CQD nanoprobes for selective sensing of heavy metal ions

In this work, a one-step pyrolysis technique is employed to synthesize porphyrin based carbon quantum dots (Porp-CQDs). The as-synthesized Porp-CQDs permit fluorescence “on/off” strategies to detect heavy metal ions. The structural formation of the Porp-CQDs with optical properties is confirmed through characterization techniques like UV–visible, fluorescence spectroscopy, HR-TEM, AFM, X-ray diffraction, and FT-IR studies. Porp-CQDs have an average particle size of 2.4 nm and a spherical shape with a semi-crystalline appearance. The excitation wavelength appears at 434 nm corresponding to the π-π* electronic transition of the soret band between the HOMO and LUMO energy levels with emission at 670 nm. The CV curves of the modified Porp-CQDs/GCE at a scan rate of 10 mV s−1 and Porp-CQDs/GCE exhibits good oxidation and reduction peaks at 1.43 V and − 0.36 V, respectively. The metal ion sensing mechanism is driven through the structure of the porphyrin core which makes it easy to form transition complexes with various metal ions in the central cage of the system. Porphyrins tagged on CQDs have been used as active sensing components in this work. The Porp-CQDs effectively sensed the Zn2+ metal ions with a limit detection of 75 μM in bore well water analysis.

Synthesis and Photovoltaic Performance of β-Amino-Substituted Porphyrin Derivatives.

New β-amino-substituted porphyrin derivatives bearing carboxy groups were synthesized and their performance as sensitizers in dye-sensitized solar cells (DSSC) was evaluated. The new compounds were obtained in good yields (63-74%) through nucleophilic aromatic substitution reactions with 3-sulfanyl- and 4-sulfanylbenzoic acids. Although the electrochemical studies indicated suitable HOMO and LUMO energy levels for use in DSSC, the devices fabricated with these compounds revealed a low power conversion efficiency (PCE) that is primarily due to the low open-circuit voltage (Voc) and short-circuit current density (Jsc) values.

Biosynthesis of Pt doped Zn bimetallic nanoparticles by using Polygonum glabrum extract for colorimetric, fluorimetric (Ni2+, Hg2+ and Fe2+) ions sensing and photocatalytic degradation of organic dye with electrochemical techniques

In the present study we aimed to explore the biosynthesis and characterization of monometallic platinum nanoparticles (PtNPs), zinc oxide nanoparticles (ZnONPs) are compared to the Pt doped ZnONPs (Pt-ZnONPs) and its sensing, electrochemical, photocatalytic properties. The bimetallic Pt-ZnONPs was synthesized by using Polygonum glabrum leaves extract; it acts as reducing agent and stabilizing agent. The analysis of colorimetric and fluorimertic sensing methods to determine the highly detection of Ni2+, Hg2+ and Fe2+ ions. The optical properties were characterized by UV-visible, FT-IR, XRD, XPS, SEM-EDX and TEM-SAED analysis. The synthesized monometallic PtNPs and ZnONPs are well dispersed spherical and hexagonal particles with sizes ranging from 8 nm to 25 nm. Electrochemical analysis were carried out the synthesized monometallic and bimetallic Pt-ZnONPs oxidation with reduction potentials by using cyclic voltammetry with UV-visible absorption spectroscopy based on band gap energy to calculation of LUMO and HOMO energy levels. The photocatalytic activities with band gap energy 96% for MeB indicated that only Pt doped ZnONPs for bimetallic Pt-ZnONPs nanocatalyst as compared to monometallic PtNPs and ZnONPs for single metal nanocatalyst actions. The highly sensitivity of Ni2+, Hg2+ and Fe2+ ions are combined with synthesized NPs extended to the oxidation-reduction potential for Pt2+ by Zn2+ ions may find sensitivity for trace different metal ions of pollution level with environmental sensing and photocatalytic applications.

Acceptor molecules with Carbon–Carbon singly bonded central and terminal units for efficient P3HT-based organic solar cells

Herein, we synthesized two small molecules named as 4TBTCN and 6TBTCN with strongly electron-rich 4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydrothieno[3′,2′:4,5]cyclopenta[1,2-b]thieno[2″,3′′:3′,4′]cyclopenta[1′,2′:4,5]thieno[2,3-d]thiophene or 6,6,12,12-tetrakis(4-hexylphenyl)-6,12-dihydrothieno[2″,3′′:4′,5′]thieno[3′,2′:4,5]cyclopenta[1,2-b]thieno[2‴,3‴:4″,5′′]thieno[2″,3′′:3′,4′]cyclopenta[1′,2′:4,5]thieno[2,3-d]thiophene as central unit and weak electron-withdrawing benzo[c] [1,2,5] thiadiazole-4-carbonitrile as termini, which were connected by C–C single bond. Both molecules exhibited medium optical bandgap and high-lying frontier molecular orbital energy levels, which were matched with those of the representative low-cost polymer donor P3HT. Moreover, 4TBTCN and 6TBTCN showed high stability under continuous illumination and base condition, owing to a lack of exocyclic vinyl group between the central unit and end group. Compared to P3HT:6TBTCN, P3HT:4TBTCN blend system displayed lower miscibility and thus more distinct phase separation, leading to more efficient charge transport and collection. Although the LUMO energy level of 4TBTCN was 0.15 eV deeper than that of 6TBTCN, the energy loss for P3HT:4TBTCN based device was similar to that of P3HT:6TBTCN based device. As a result, P3HT:4TBTCN based device displayed a similar open-circuit voltage but higher fill factor and short-circuit current density, yielding a superior power conversion efficiency, in comparison to P3HT:6TBTCN based device. This work provides a new strategy for design of efficient and stable acceptor molecules.

Constructing Efficient ASM Organic Solar Cells Based on DRCN5T

All-small-molecule (ASM) donor-acceptor materials have the advantages of good molecular reproducibility and relatively simple synthesis operations. In this paper, the small molecule donor material DRCN5T was synthesized and its related properties were investigated. The HOMO result of DRCN5T was determined to be -5.27 eV. The LUMO energy level was -3.62 eV. In terms of UV-visible absorption, the DRCN5T thin film exhibited a redshift due to π-π stacking as compared to CF solution. Finally, DRCN5T:IDIC-based ASM devices were prepared. After the solvent vapor annealing treatment, the device performances were significantly enhanced, with an open-circuit voltage (VOC) of 0.95 V, a short-circuit current density (JSC) of 12.66 mA cm-2 and a fill factor (FF) of 61.40%, and the power conversion efficiency (PCE) was 7.40%.

Synthesis, photophysical, electrochemical, theoretical and self-assembly investigation of tetraphenylethene tethered arylimidazoles

To understand the comparative structure–property relationships, we have designed and synthesized 4,5-diphenyl-2-(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole, coded as JR-1 and 4,4′-(2-(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole-4,5-diyl)bis(N,Ndimethylalanine)coded as JR-2. Here, we conducted various analyses, including, structural, photophysical, thermal, electrochemical, and computational studies, to gain a deeper understanding of introduction electron releasing N,N-dimethyleamine groups on later one. The molecules exhibit high thermal stability (200 − 300 °C) low band gap (2.75 – 3.26 eV) and comparable HOMO (−4.81 to − 5.35 eV) and LUMO (−2.06 to − 2.09 eV) energy levels with those of calculated and reported ambipolar materials. The UV–vis absorption was observed in the range of 300–400 nm for JR-1 and 300 − 440 nm for JR-2. These compounds exhibit distinct mechanochromism, solvatochromism, aggregation-induced emission, and aggregation-caused quenching and selective sensing. Interestingly, JR-1 exhibits mechanochromism without solvatochromism, while JR-2 is solvatochromic without mechanochromism. Due to incorporation of N,N-Dimethylphenylamine donating groups on imidazole leads to solvatochromicity and aggregation-caused quenching. Moreover, their optical properties differ significantly in dilute solutions compared to its solid state due to distinct molecular arrangements. Consequently, morphological studies reveal the formation of 3D rod and spear-shaped s supramolecular self-assembly structures in different solvent mixtures. This research work offers a fundamental strategy for the design of fluorophores for optoelectronic applications.

Bridging the gap to practicality: A green methanesulfonic acid system enhanced with synergistic additives for efficient and high-quality lead electro-refining

Green methanesulfonic acid (MSA) system offers a promising alternative to the traditional fluosilicic acid (H2SiF6) method for lead electro-refining. However, the MSA system has yet to produce efficient electro-refining process, high-quality cathodic lead and stable anodic dissolved layer concurrently, which is crucial for its practical application. Herein, we propose an MSA-based system — enhanced with Lugalvan NES (NES) and calcium lignosulfonate (CL) — for efficient and high-quality lead electro-refining. In both proof-of-concept and separate high-flux flow operations, we achieve a low energy consumption of 73.06 kWhe/t Pb and a high Faradaic efficiency of 99.11 %. Dense deposits with ultra-low grain sizes under 20 nm and high purities of over 99.99 %, and uniform dissolved layers with moderately adhesive anode mud are obtained. Theoretical simulations reveal the HOMO and LUMO energy levels of the additives and their adsorption energy on the Pb interface. Electrochemical analysis indicates a cathodic three-dimensional nucleation process and an anodic mechanism of uniform dissolution. A modular micro-kinetics model is developed to elucidate energy performance. These advances represent a significant step forward for lead electro-refining, achieving efficient operation and high-quality output while reducing energy use and surpassing the efficacy of the traditional method.

Synthesis of new [6]helicene derivatives for OLED applications. Experimental photophysical and chiroptical properties and theoretical investigation

Six-membered helicenes with specific functionalities were synthesized in good overall yields (40 %-73 %) through a concise photochemical method, allowing for their comprehensive characterization. The racemic mixtures were effectively resolved into their P- and M-enantiomers with high optical purity (97.56 %-100 % ee) by using chiral HPLC. This separation showcased remarkable optical activity, revealing substantial optical rotations (e.g., +2500–3000 for the (P)-enantiomer at λ = 589 nm) and notable electronic circular dichroism (ECD) signals. The organic helical species showed a strong absorption in the UV region and exhibited a red shifted emission, resulting in a quantum yield of 0.12–0.21. Moreover, they demonstrated irreversible one-electron oxidation and reduction processes, and their HOMO and LUMO energy levels were estimated via electrochemical methods. Utilizing DFT and TD–DFT computational approaches, we accurately predicted the electronic absorption and ECD spectra, as well as the frontier molecular orbitals (FMOs), aligning closely with experimental observations. Furthermore, in-depth analyses of absorption and ECD spectra, molecular electrostatic potential (MEP), and reduced density gradient (RDG) through quantum chemical calculations offered insights into the fundamental characteristics of these materials. The collective properties strongly indicate the potential application of these helicenes in electroluminescent and OLED devices, underscoring their promise as candidates in optoelectronic applications.

Broadband all-polymer photodetectors with ultrahigh detectivity above 1014 Jones enabled by fine-tuned molecular stacking via facile random terpolymerization

All-polymer photodetectors (all-PPDs) show great potential in the next generation of electronic devices. In order to achieve stable high-performance all-PPDs, the balance between the ordered molecular stacking of a single polymer and the miscibility of donor/acceptor is a key issue. N2200 is a typical acceptor polymer with excessive self-aggregation, and regulating the molecular stacking rationally of N2200 is still challenging. Herein, we demonstrate a facile approach of terpolymerization to solve the dilemma by introducing the small amount of ITIC unit as a “crystal defect” into over self-assembled N2200 to synthesize a new terpolymer NTI. Compared with N2200, NTI shows higher light absorption coefficient and higher LUMO energy level. Notably, the crystallinity of NTI and the miscibility of J71/NTI are remarkably balanced, leading to better film morphology and more balanced carrier mobility of the active layer. Therefore, the J71:NTI device features an ultrahighspecific detectivity (D*) of 1.2 × 1014 Jones, a fast response speed of 1.31/2.50 μs, and a large linear dynamic range of 105 dB under −0.1 V bias. To our knowledge, it is the highestD* for all-PPDs reported. Furthermore, J71:NTI device shows better spectral response stability over 30 days and was successfully applied as the human real-time blood oxygen signal monitor. This work demonstrates a facile approach to balance the ordered molecular stacking and the miscibility enabling stable high-performance all-PPDs.