Distribution Of Frontier Molecular Orbitals Research Articles

Tetraborated Intrinsically Axial Chiral Multi‐resonance Thermally Activated Delayed Fluorescence Materials

Chiral multi‐resonance thermally activated delayed fluorescence (CP‐MR‐TADF) materials hold promise for circularly polarized organic light‐emitting diode (CP‐OLED) and 3D display. Herein, we present two pairs of tetraborated intrinsically axial CP‐MR‐TADF materials, R/S‐BDBF‐BOH and R/S‐BDBT‐BOH, with conjugation‐extended bidibenzo[b,d]furan and bidibenzo[b,d]thiophene as chiral sources, which effectively participate in the distribution of frontier molecular orbitals. Due to the heavy‐atom effect, sulfur atoms are introduced to accelerate the reverse intersystem crossing process and increase efficiency of molecules. R/S‐BDBF‐BOH and R/S‐BDBT‐BOH manifest ultra‐pure blue emission peaking at 458/459 nm with full width at half maximum of 27 nm (0.16 eV), photoluminescence quantum yields of 90%/91% and dissymmetry factors (|gPL|) of 6.8 × 10‐4/8.5 × 10‐4, respectively. Correspondingly, the CP‐OLEDs exhibit good performances with external quantum efficiency of 30.1% and |gEL| factors of 1.2 × 10‐3.

Tetraborated Intrinsically Axial Chiral Multi-resonance Thermally Activated Delayed Fluorescence Materials.

Chiral multi-resonance thermally activated delayed fluorescence (CP-MR-TADF) materials hold promise for circularly polarized organic light-emitting diode (CP-OLED) and 3D display. Herein, we present two pairs of tetraborated intrinsically axial CP-MR-TADF materials, R/S-BDBF-BOH and R/S-BDBT-BOH, with conjugation-extended bidibenzo[b,d]furan and bidibenzo[b,d]thiophene as chiral sources, which effectively participate in the distribution of frontier molecular orbitals. Due to the heavy-atom effect, sulfur atoms are introduced to accelerate the reverse intersystem crossing process and increase efficiency of molecules. R/S-BDBF-BOH and R/S-BDBT-BOH manifest ultra-pure blue emission peaking at 458/459 nm with full width at half maximum of 27 nm (0.16 eV), photoluminescence quantum yields of 90%/91% and dissymmetry factors (|gPL|) of 6.8 × 10-4/8.5 × 10-4, respectively. Correspondingly, the CP-OLEDs exhibit good performances with external quantum efficiency of 30.1% and |gEL| factors of 1.2 × 10-3.

Effective donor and acceptor modifications of carbazole-benzonitrile thermally activated delayed fluorescence molecules enabling high-performance OLEDs

Carbazole-benzonitrile derivatives (CzBNs) have great potential to enable thermally activated delayed fluorescence (TADF) molecules with both high efficiency and good stability simultaneously. However, the device performances of most CzBN-based organic light-emitting diodes (OLEDs) still lag behind other types of TADF molecules. In this work, we proposed a design strategy to construct efficient CzBN-TADF molecules through acceptor and donor modifications. The cyano-modified acceptor enables the extension of the lowest unoccupied molecular orbital while mostly preserving the overlapped area with the highest occupied molecular orbital. The optimized distributions of frontier molecular orbitals contribute to tiny singlet-triplet energy gaps while maintaining a high radiative decay rate. The incorporation of tert-butyl units in the donor groups further enhances the TADF property of resulted tPCNBN molecule due to suppressed non-radiative decay and reduced exciton self-quenching. Accordingly, OLEDs based on tPCNBN present the best device performances, such as a maximum external quantum efficiency of 33.1 % at 400 cd m−2, which is still as high as 26.3 % at a high luminance of 4000 cd m−2, demonstrating relatively low efficiency roll-off. These results confirm the effectiveness of the proposed design strategy in developing efficient and stable CzBN-TADF materials and devices.

Peripheral anchoring groups strategy enables frontier molecular orbital delocalization and fast radiative decay of narrowband ultraviolet emitters for suppressing efficiency roll-off

Ultraviolet organic light-emitting devices with neat film as emissive layer commonly suffer from low brightness, poor color purity, and severe efficiency roll-off owing to the intrinsic molecular properties. Herein we present a peripheral anchoring functional group approach to decorating “space-crowded donor−acceptor−donor” type carbazole-pyridine derivatives, for developing stable and bipolar ultraviolet fluorophores featuring narrowband emission. The introduction of anchoring group not only increases the delocalization of frontier molecular orbital distributions, enhancing the bipolar transport ability, but also confers the moderate rigidity and torsion of molecular conformation that shortens fluorescence lifetimes in aggregation state. Consequently, the non-doped devices with phenylcarbazole and naphthalene modified emit stable ultraviolet emission with the peaks of 395 and 388 nm and the full width at half maximums of 39 and 43 nm. Moreover, the maximum external quantum efficiencies (EQEs) of ∼4.0% and a mitigated efficiency roll-off at the high brightness of 3000 cd m−2 (EQE3000: ∼3.8%) are achieved, which provides an opportunity for ultraviolet OLEDs to realize the applications at high brightness levels.

Indolocarbazole Derivatives for Highly Efficient Organic Light‐Emitting Diodes

AbstractSince the discovery of the organic light‐emitting diode (OLED), scientists worldwide have dedicated extensive efforts to enhance the efficiency and reliability of devices, striving for superior performance. Various molecular structures have undergone structural modifications to assess their suitability in achieving the desired outcomes. This review focuses on indolo[3,2,1‐jk]carbazole (ICz), a building block that has garnered considerable attention within the OLED community. The rigid and fused ICz core induces a multiresonance effect through an alternating distribution of frontier molecular orbitals. Notably, ICz‐based thermally activated delayed fluorescence emitters exhibit a full width at half maximum below 20 nm, ensuring high color purity, and boast an external quantum efficiency above 30%, comparable to state‐of‐the‐art narrow‐emitting boron–nitrogen‐type materials. Furthermore, the ICz core is a building block in host and metal complexes, enhancing stability, efficiency, and color purity. Consequently, the ICz core is promising as a central component in host and emitters, improving OLED device performance. This review aims to succinctly summarize studies on ICz‐based organic materials within the OLED field, offering insights into future perspectives regarding developing and applying ICz‐derived organic compounds.

Bistriazolotriazole-tetramine: commendable energetic moiety and cation.

Various 7H,7'H-[6,6'-bi[1,2,4]triazolo[4,3-b][1,2,4]triazole]-3,3',7,7'-tetramine (A) based nitrogen-rich energetic salts were designed and their properties explored. All energetic salts possess relatively high nitrogen content (> 48%), positive heats of formation (> 429kJ/mol) and stability owing to a significant contribution from fused backbone. The cationic component shows a very high heat of formation (2516kJ/mol); therefore, it is highly suitable for enthalpy enhancement in new energetic salts. The cation was paired with the energetic anions nitrate (NO3-), perchlorate (ClO4-), dinitromethanide (CH(NO2)2-), trinitromethanide (C(NO2)3-), nitroamide (NHNO2-), and dinitroamide (N(NO2)2-) to improve oxygen balance and detonation performance. Designed salts show moderate detonation velocities (7.9-8.7 km/s) and pressures (23.8 - 33.1 GPa). The distribution of frontier molecular orbitals, molecular electrostatic surface potentials, QTAIM topological properties, and noncovalent interactions of designed salts were simulated to understand the electronic structures, charge distribution in molecules, hydrogen bonding, and other nonbond interactions. The predicted safety factor (SF) and impact sensitivity (H50) of designed salts suggest their insensitivity to mechanical stimuli. This work explored the 7H,7'H-[6,6'-bi[1,2,4]triazolo[4,3-b][1,2,4]triazole]-3,3',7,7'-tetramine as a suitable cationic component which could be promising and serve exemplarily in energetic materials. The optimization and energy calculations of all the designed compounds were carried out at the B3LYP/6-311 + + G(d,p) and M06-2X/def2-TZVPP levels, utilizing the Gaussian software package. The molecular surface electrostatic potential, quantum theory of atoms in molecules (QTAIM), reduced density gradient (RDG), and noncovalent interaction (NCI) analysis were performed by employing Multiwfn software. The EXPLO5 (v 7.01) thermochemical code and PILEM web application were used to predict the detonation properties.

Preparation of chlorophyll compounds and simulation of DFT optical properties assisted screening of photosensitizers from Ginkgo biloba leaves

Chlorophyll compounds (Chls) from Ginkgo biloba leaves (GBL) are non-toxic natural pigments characterized by highly conjugated molecules and special spectra, making them ideally potential photosensitizers (PSs) in photodynamics therapy (PDT). In this study, 4 Chls were isolated from Ginkgo biloba polyprenols (GBPPs) wastes by using silica gel column separation and high performance liquid chromatography (HPLC). In addition, two new chlorophyll derivatives were successfully synthesized with chlorin e6 as the primary raw material. To evaluate and identify superior chlorophyll PSs, Density Functional Theory (DFT) and Density Functional Theory (TD-DFT)were employed to decode the microscopic and spectral properties of Ginkgo biloba Chls (GBChls). The spectral absorption, optical stability and reactive oxygen species (ROS) production of GBChls were further analyzed through comparisons of their frontier molecular orbital layout, charge distribution and excitation energy properties. Our results show that about 63 % absorption in the Q band for 14 GBChls comes from the π⇢π* transition from the highest occupied orbital (HOMO) to the lowest unoccupied orbital (LUMO), indicating the favorable delocalization effect of these GBChls. In particular, those GBChls with the long chain of the phytyl group exhibited higher total electron energy and thus could significantly increase the light stability. However, the large spatial volume and hydrophobicity of these compounds with the phytyl group chain was unfavorable for cellular uptake, leading to low ROS in cells. The electronegativity of porphin macrocycles in GBChls positively correlates with the intracellular ROS production rate, meaning that the former likely promotes the energy transfer between PSs and molecular oxygen during type II photoreaction. Among the GBChls, chlorin e6 demonstrated the highest ROS yields in DMF, while purpurin 18 compounds displayed long-wavelength absorption (698 nm), strong Q-band absorption, good optical stability, and high intracellular ROS production. Our findings highlight that chlorin e6 and purpurin 18 are most potential PSs anticancer drugs and offer new research perspectives for the processing and utilization of GBL resources.

Towards Development of High-Performance Perovskite Solar Cells Based on Pyrrole Materials for Hole Transport Layer by Using Computational Approach

Perovskite solar cells (PSCs) have emerged as innovative materials in advanced photovoltaic technology due to their enhanced efficiency and good stability. While considering role of dopant materials in HTMs especially Spiro-OMeTAD through previous studies, a bi-functional dopant named PFPPY has been brought into special attention. Based on framework of experimentally synthesized PFPPY, five dopant molecules (P1–P5) have been designed through structural alterations at peripheral sites. These newly developed molecules, sharing a common core i.e. 1,4-dihydropyrrolo[3,2-b]pyrrole (PPY), were then theoretically studied and related to reference via computational approach. Distribution of frontier molecular orbitals (FMOs) along with density of states, spectral properties, reorganizational energies, binding energy, and transition density matrix analysis was practiced at [Formula: see text]B97XD functional using DFT and TD–DFT methodology. Bathochromic shift of absorption (in dichloromethane) was clearly observed for all designed dopants (P1–P5) than reference PFPPY which sets the ways for reduced optical band gaps ([Formula: see text]. The energy gaps ([Formula: see text] of these five novel designed materials were found to be lesser comparaed to PFPPY which leads to excellent ICT properties. Of all dopant molecules, highest dipole moment (6.511401 D) possessed by P4 is credited to its maximum absorption peak (1008 nm) in infrared region. However, greater hole transfer rate was disclosed by P1 relative to other designed dopants because of its lowest reorganization energy values. According to above computed results, we expect that molecular engineering of pyrrole-based dopant molecules (P1–P5) will allow them to act as promising HTMs. Conclusively, these molecules have potential to substitute PFPPY and are highly recommend in photovoltaic field for future work.

A DFT Study on the Impact of Saturated and Conjugated Side Chains on the Optoelectronic Performance of Y-series Nonfullerene Acceptors

Organic photovoltaic (OPV) consisting of nonfullerene acceptors have been found to be excellent candidates for harnessing solar energy. Extensive studies are being carried out to modify structures in a number of ways to enhance their efficiency. These include modifications in the acceptor part, use of efficient backbones and insertion of pi spacers. One strategy is the attachment of donor side chains for better assembly of molecules. In this work, the effect of theoretically designed side chains on electrochemical and optical properties of OPVs was studied. A series of molecules consisting of saturated (SC1-4) and conjugated donor (CD1-2) were designed and studied computationally for their potential OPV properties. Parameters like Band gap, absorption spectrum, frontier molecular orbital distribution, binding energy, fill factor, open circuit voltage, excitation energies, density of states (DOS) and transition density matrix (TDM) were studied using DFT and TD-DFT methods. Unsaturated side chains although exhibit better performance in terms of open circuit voltage and hole mobility but reduce light harvesting efficiency. All saturated side chain modifications showed improvement in fill factor and open circuit voltage than reference molecule. SC3 modification with red shift and smaller band gap showed the best performance.

Small thiophene-based molecules with favorable properties as HTMs for perovskite solar cells or as active materials in organic solar cells

Computational investigations are carried out to design new molecules based on thiophene cores substituted in several positions using different end-capped electron-donating groups formed from triphenylamine or OMe-triphenylamine that can be used as HTMs in Perovskite Solar Cells (PSCs), or as an active layer in Organic Solar Cells. The influence of π-extension on the charge transfer process is also probed by inserting two azomethine groups between acceptor and donor (D-π-A-π-D) moieties. The designed molecules (T10,12,13,15) were compared with the two synthesized molecules (T11,14) that have been applied as HTMs in a PSC. Density functional theory (DFT) and time-dependent DFT (TD-DFT) were chosen to calculate different chemical parameters of these molecules. Different chemical parameters were calculated to make the link between geometrical parameters and the efficiency, solubility, and stability of the under-probed compounds. The results show that all molecules can be used adequately with the perovskite matrix because of their sufficient deep HOMOs levels. The optoelectronic properties of the D-A-D molecules show no competition with the light-harvesting of the perovskite layer, while D-π-A-π-D compounds show a slight overlap with the absorption band of perovskites. All molecules indicate a faster hole-transport rate and an easy electron-hole pairs dissociation into free charge carriers, which facilitates the hole transport and enhances open-circuit voltage. Adding a second thiophene unit in the central core reinforces the structure's flexibility and improves Frontier Molecular Orbital's electronic density distribution, while inserting azomethine groups is advantageous for the molecule's solubility. Their short gaps, higher radiative lifetimes, and visible light absorbance make T12,15 good candidates for their usage in organic solar cell applications. A spontaneous solvation process within dichloromethane for all the investigated molecules was proved based on the high negative free energies.

Indolocarbazole-based deep-blue multiple-resonance narrowband emitters and efficient organic light-emitting diodes

Developing organic deep-blue multiple-resonance (MR) emitters with narrow full widths at half maximum (FWHMs) is of great significance for improving the color purity of organic light-emitting diodes (OLEDs). Herein, two MR polycyclic aromatic hydrocarbons with three-indolo[3,2,1-jk]carbazole (ICz)-embedded fragments are designed and synthesized via prolonging multiple-ICz strategy, accompanied by a deep-blue narrowband emission of 452 nm, a FWHM of 20 nm, and high photoluminescence quantum yield of 76%. Theoretical studies unveil that enlarging the atomically separated frontier molecular orbital distribution and extending the π-electron delocalization on the PAH skeleton are conducive to bathochromic-shift emission and simultaneously maintaining a small FWHM. In addition, the optimized blue OLEDs fabricated with the nitrogen-embedded MR emitter achieved a high external quantum efficiency of 12.6%.

Three-Dimensional Anisotropic Carrier Mobility and Structure–Property Relationships for [1]Benzothieno[3,2-b][1]benzothiophene Derivatives: A Theoretical Study

Through the Marcus electron-transfer theory combined with the random walk technique for the charge-carrier diffusion process, we simulated the three-dimensional (3D) distributions of hole and electron mobilities for [1]benzothieno[3,2-b][1]benzothiophene (BTBT) and its derivatives. Our predicted mobility ranges agree well with the measured field-effect mobility of the BTBT derivatives. We further analyzed the charge-transfer mobility anisotropy of the studied compounds, and the optimum conducting-channel direction relative to the crystal axis was determined, which provides a reliable reference to assist in the performance optimization of field-effect transistors (FETs). Moreover, we analyzed in detail the influences of different substituents on the reorganization energies, ionization energies, electron affinities, frontier molecular orbital charge distributions, and solid-state packing motifs of the BTBT. It was found that the reorganization energies and energy barrier of charge injection effectively decreased with the fusion of the thiophene ring. However, the herringbone packing of BTBT is transformed to π stacking at a local site; as a result, the hole and electron mobilities of BTBT decreased slightly. In comparison, attaching electron-withdrawing −COPhF to BTBT not only increases the electron affinities significantly but also increases the electronic couplings and decreases the reorganization energy related to the electron transfer. It provides a promising way to design n-type or ambipolar organic semiconducting materials.

Novel arylazo nicotinate derivatives as effective antibacterial agents: Green synthesis, molecular modeling, and structure-activity relationship studies

A series of novel arylazo nicotinates compounds, denoted as (3a-k and 5a-d) were synthesized and characterized through the reaction of 3-oxo-arylhydrazonals with various active methylene nitriles using microporous zeolite as a green catalyst. The structure of the newly prepared heterocycles was determined using various spectral techniques such as MS, IR, NMR, and elemental analysis. The antibacterial activity of these compounds against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) was evaluated, and it was found that all arylazo nicotinate compounds were highly effective against both gram-negative (E. coli) and gram-positive (B. subtilis) bacterial strains. The efficacy of the developed arylazo nicotinate derivatives as antimicrobial agents against E. coli and B. subtilis was evaluated using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values. Density-functional theory (DFT) was employed to investigate the structure–activity relationships of recently synthesized compounds. Gaussian 09 software was utilized to compute various molecular properties, including the distribution of frontier molecular orbitals (FMO), the energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), the energy gap (Eg), as well as several biological activity descriptors such as ionization potential (IP), electron affinity (EA), chemical potential (μ), chemical hardness (η), electronegativity (χ), global softness (S), and electrophilicity index (ω). The results of the FMO calculations revealed that the arylazo nicotinates had effective charge separation and distinct HOMO/LUMO energy levels for each compound, as reflected by the different Eg values. The Eg values were found to have a strong correlation with the antibacterial efficacy against E. coli and B. subtilis. The highest and lowest efficacy among the molecules (3a-k) were observed for compounds 3b (Eg = 3.36 eV) and 3 k (Eg = 2.27 eV), respectively, while the highest and lowest efficacy among the molecules (5a-d) were observed for compounds 5d (Eg = 3.33 eV) and 5c (Eg = 2.94 eV), respectively.

Design, synthesis and photophysical properties of a (quinolin-3-yl)methanone-based thermally activated delayed fluorescence emitter

A new (quinolin-3-yl)methanone-based emitter, PQLM-DMAC, is designed with a highly twisted donor-acceptor conformation. A simple synthetic approach is used to prepare PQLM-DMAC, and its thermal, theoretical, photophysical, and electroluminescence are systematically studied to highlight the applicability in organic light-emitting diodes (OLEDs). PQLM-DMAC exhibits separated frontier molecular orbital distribution and thus can emit prominent thermally activated delayed fluorescence (TADF) suitable for triplet harvesting in OLEDs. Furthermore, PQLM-DMAC exhibits short excited-state lifetimes and decent photoluminescence quantum yield, enabling high efficiencies and low efficiency roll-offs in OLEDs.

Isomer engineering to adjusting full width at half maximum and emission wavelength for efficient solution-processed red OLEDs

Given the great effect of red dyes with high color purity on ultrahigh-definition displays, exploring new red fluorophores remains urgent. In this work, two novel boron dipyrromethene derivatives (BODIPYs), named o-OMB and p-OMB, were designed and synthesized by adjusting the substitution position of methoxy group. The introduction of tert-butylbenzene units increases steric hindrance and adjacent distance between the host and guest to inhibit adverse Dexter energy transfer. Regioisomerization of methoxy group has a certain impact on photophysical properties, including the distribution of frontier molecular orbitals and recombination energy. The recombination energy of p-OMB is much smaller than that of o-OMB, and the Eg of the former is 1.94 eV less than that of the latter 2.02 eV. Compared with o-OMB, p-OMB with para-substituent has narrower emission spectrum with a FWHM of 37 nm and red-shifted emission wavelength of 634 nm. The solution-processed based-p-OMB OLEDs show a maximum EQE of 1.3% and standard red emission with CIE coordinates of (0.67, 0.33) when using PhCz-4CzTPN as a sensitizer.

Optoelectronic properties of Portulacaxanthin III (PXIII), GQD/Os-GQD-PXIII nanocomposites, and their coupling with photoanode in dye-sensitized solar cells: Molecular and periodic DFT calculations

In this work, the optoelectronic properties of a naturally occurring dye, Portulacaxanthin III (PXIII), were investigated. To improve the performance of PXIII dye, it was hybridized with graphene quantum dot (GQD) undoped and doped with Os at the central position to form two nanocomposites (PXIII-GQD and Os-GQD-PXIII), and their optoelectronic properties were also investigated. Parameters such as frontier molecular orbital energies and distributions, absorption and emission properties, excited-state lifetimes, and hole and electron reorganization energies were calculated at two molecular (HCTH and CAM-B3LYP) DFT functionals and their counterparts TDDFT functionals in the gas phase and with the PCM model to mimic the effect of the solvent in three solvents: chloroform, acetonitrile, and water. The variation of the abovementioned molecular parameters as a function of media polarities (dielectric constants) was investigated. In addition, the coupling with the photoanode TiO2 anatase (101) with a periodic DFT functional was also investigated. The output from this work demonstrated the better overall performance of the nanocomposites (doped and undoped). Since they have better energy level alignments, red-shifted and broader absorption in the Vis and IR regions, better HOMO and LUMO charge separation, and stronger adsorption on the photoanode.

Integrating the atomically separated frontier molecular orbital distribution of two multiple resonance frameworks through a single bond for high-efficiency narrowband emission.

Atomically separated frontier molecular orbital (FMO) distribution plays a crucial role in achieving narrowband emissions for multiple resonance (MR)-type thermally activated delayed fluorescence emitters. Directly peripherally decorating a MR framework with donor or acceptor groups is a common strategy for developing MR emitters. However, this approach always induces bonding features and thus spectral broadening as a side effect. How direct donor/acceptor decoration enhances atomic FMO separation while avoiding bonding features has not been explored. For this aim, two MR derivatives are synthesized by integrating two MR frameworks at different sites. Following resonance alignment, DOBNA-m-CzBN avoids breaking nonbonding FMO features at the single connecting bond and shows enhanced MR characteristics, with a sharp emission at 491 nm and a full width at half maximum (FWHM) of 24 nm/118 meV. Conversely, DOBNA-p-CzBN emerges as a bonding feature due to its continuous π-conjugation extension, with a broadened FWHM of 26 nm/132 meV peaking at 497 nm. Impressively, both emitters exhibit outstanding external quantum efficiencies of 37.8-38.6% in organic light-emitting diodes (OLEDs), demonstrating improved performance with rigid acceptor decoration. Distinctly, the electroluminescence of DOBNA-m-CzBN shows a narrower FWHM than that of DOBNA-p-CzBN. This work for the first time reports the enhancement of atomic FMO separation for MR emitters via peripheral decoration through a single bond and provides a more comprehensive illustration for further development of MR emitters.

Design and Synthesis of N‐Alkylaniline‐Substituted Low Band‐Gap Electron Acceptors for Photovoltaic Application

Comprehensive SummaryA novel electron donating unit, namely N‐octyl‐N‐phenyl‐thiophene (OPT), was designed in preparing electron acceptors with non‐fused ring chemical structures. By introducing different functional atoms/groups into the para‐position of phenyl in the OPT units, three non‐fused ring acceptors (NFREAs), C8‐2F, FC8‐2F and MeC8‐2F, were synthesized. The absorption spectrum of the three acceptors can be extended to about 950 nm with band‐gaps of 1.28—1.32 eV due to the strong electron donating ability of OPT. The frontier molecular orbital distribution of OPT based molecules obtained by quantum chemistry calculation results reveals that their energy alignment can be finely tuned to meet different requirements. Moreover, by changing the substituents on the OPT units, their Flory‐Huggins interaction parameter (χ) with the donor will be greatly influenced and different phase separation behavior can be accomplished. After blended with PBDB‐TF, the FC8‐2F‐based cell yields short circuit current density (Jsc) of 23.21 mA·cm–2, fill factor (FF) of 72.11% and the highest power conversion efficiency (PCE) of 12.42%. This work provides a new pathway for molecular design of new NFREAs, and demonstrates the application potential of OPT unit in realizing low band‐gap photovoltaic materials.

Synthesis of Highly Luminescent Chiral Nanographene

AbstractChiral nanographenes with both high fluorescence quantum yields (ΦF) and large dissymmetry factors (glum) are essential to the development of circularly polarized luminescence (CPL) materials. However, most studies have been focused on the improvement ofglum, whereas how to design highly emissive chiral nanographenes is still unclear. In this work, we propose a new design strategy to achieve chiral nanographenes with highΦFby helical π‐extension of strongly luminescent chromophores while maintaining the frontier molecular orbital (FMO) distribution pattern. Chiral nanographene with perylene as the core and two dibenzo[6]helicene fragments as the wings has been synthesized, which exhibits a record highΦFof 93 % among the reported chiral nanographenes and excellent CPL brightness (BCPL) of 32 M−1 cm−1.

Synthesis of Highly Luminescent Chiral Nanographene.

Chiral nanographenes with both high fluorescence quantum yields (ΦF ) and large dissymmetry factors (glum ) are essential to the development of circularly polarized luminescence (CPL) materials. However, most studies have been focused on the improvement of glum , whereas how to design highly emissive chiral nanographenes is still unclear. In this work, we propose a new design strategy to achieve chiral nanographenes with high ΦF by helical π-extension of strongly luminescent chromophores while maintaining the frontier molecular orbital (FMO) distribution pattern. Chiral nanographene with perylene as the core and two dibenzo[6]helicene fragments as the wings has been synthesized, which exhibits a record high ΦF of 93 % among the reported chiral nanographenes and excellent CPL brightness (BCPL ) of 32 M-1 cm-1 .