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Glass transition temperature, Tg, is the key quantity for assessing morphological stability and molecular ordering of films of organic semiconductors. A reliable prediction of Tg from the chemical structure is, however, challenging, as it is sensitive to both molecular interactions and analysis of the heating or cooling process. By combining a fitting protocol with an automated workflow for forcefield parameterization, we predict Tg with a mean absolute error of ~20 °C for a set of organic compounds with Tg in the 50–230 °C range. Our study establishes a reliable and automated prescreening procedure for the design of amorphous organic semiconductors, essential for the optimization and development of organic light-emitting diodes.

A recent implementation of time-dependent tight-binding density functional theory is employed in excited state molecular dynamics for the investigation of the fluorescence quenching mechanism in 3 prototypical aggregation-induced emission systems. An assessment of the accuracy of the electronic structure method is done by comparison with previous theoretical work while dynamics simulations were extended to the condensed phase to obtain excited state lifetimes comparable to experiment. A thorough investigation is done on tetraphenylethylene in order to resolve the on-going debate on the role of specific deactivation mechanisms. Both gas phase and solvent dynamics were computed for fulvene and silole derivatives.

Despite organic/inorganic lead halide perovskite solar cells becoming one of the most promising next‐generation photovoltaic materials, instability under heat and light soaking remains unsolved. In this work, a highly hydrophobic cation, perfluorobenzylammonium iodide (5FBzAI), is designed and a 2D perovskite with reinforced intermolecular interactions is engineered, providing improved passivation at the interface that reduces charge recombination and enhances cell stability compared with benchmark 2D systems. Motivated by the strong halogen bond interaction, (5FBzAI)2PbI4 used as a capping layer aligns in in‐plane crystal orientation, inducing a reproducible increase of ≈60 mV in the V oc, a twofold improvement compared with its analogous monofluorinated phenylethylammonium iodide (PEAI) recently reported. This endows the system with high power conversion efficiency of 21.65% and extended operational stability after 1100 h of continuous illumination, outlining directions for future work., 2D perovskites are of great importance to increase both the efficiency and stability of perovskite interfaces. Motivated by the stronger halogen bond interaction, (5FBzAI)2PbI4 used as a capping layer in 3D/2D systems self‐organizes with an in‐plane crystal orientation, inducing a reproducible increase of ≈60 mV in the V oc, and remarkable operational stability.

A.M. has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 844655 (SMOLAC). This publication is based on work supported by the KAUST Office of Sponsored Research (OSR) under award nos. OSR-2018-CARF/CCF-3079 and OSR-CRG2018-3746. D.A. also acknowledges the KAUST PSE Division for hosting his sabbatical in the framework of the Division's Visiting Faculty program. D.A. acknowledges funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) for financial support through the collaborative research centers TRR 146, SPP 2196, and grant number 460766640. K.-H.L. acknowledges the financial support from the Swiss NSF Early Postdoc Mobility fellowship (grant no. P2ELP2_195156). The authors thank Kostas Daoulas, Leanne Paterson, and Naoimi Kinaret for fruitful discussions and proof-reading of the manuscript. Open access funding enabled and organized by Projekt DEAL.

Amorphous small-molecule organic materials are utilized in organic light emitting diodes (OLEDs), with device performance relying on appropriate chemical design. Due to the vast number of contending materials, a symbiotic experimental and simulation approach would be greatly beneficial in linking chemical structure to macroscopic material properties. We review simulation approaches proposed for predicting macroscopic properties. We then present a library of OLED hosts, containing input files, results of simulations, and experimentally measured references of quantities relevant to OLED materials. We find that there is a linear proportionality between simulated and measured glass transition temperatures, despite a quantitative disagreement. Computed ionization energies are in excellent agreement with the ultraviolet photoelectron and photoemission spectroscopy in air measurements. We also observe a linear correlation between calculated electron affinities and ionization energies and cyclic voltammetry measurements. Computed energetic disorder correlates well with thermally stimulated luminescence measurements and charge mobilities agree remarkably well with space charge–limited current measurements. For the studied host materials, we find that the energetic disorder has the greatest impact on the charge carrier mobility. Our library helps to swiftly evaluate properties of new OLED materials by providing well-defined structural building blocks. The library is public and open for improvements. We envision the library expanding and the workflow providing guidance for future OLED material design.

Truxene and its derivatives have been extensively employed for various applications and are considered as promising dopant-free hole transport materials (HTMs) in perovskite solar cells (PSCs). Yet, a systematic exploration of their performance for this specific application remain lacking. Here, multiscale simulations are used to investigate the key structure-property relationships of truxene derivatives featuring distinct variations to the parent core. Specifically, the role of heteroatoms, alkyl chains, and substitution site on the most relevant electronic, transport, and stability properties to high-performing PSCs are assessed. Our findings demonstrate that each of the considered truxenes are potential alternatives to the current state-of-the-art HTM Spiro-OMeTAD.

We employed first-principles calculations to investigate the lithiation mechanisms of functionalized graphene nanoribbons (GNRs) and to examine the effect of various functional groups on the electrochemical performance of graphene-based nanomaterials. In this work, we have extensively explored the Li storage behaviors of various types of functional groups located on the basal plane and those terminating the edge sites within different levels of lithiation and functionalization on GNRs. For functional groups terminating the edge sites, only ketone and its related derivatives (pyrone/quinone) can effectively enhance Li adsorption on GNRs, and the most favorable sites for Li adsorption turn out to be these edge-oxidized groups rather than the hollow sites on the basal plane. In addition, as the ketone-terminated GNRs were fully lithiated, the Li/O atomic ratio was found to be ∼1.0 and that for the ketone–ether pair (pyrone) was ∼0.5, indicating that these edge-oxidized groups can effectively enhance the Li capacity of GNRs as compared with that of graphite (Li1/6C). As regards the in-plane functional groups, the epoxy and hydroxyl groups were shown to have multiple Li uptakes on the basal plane and appeared to serve as the nucleation centers for Li clustering, thereby resulting in the great enhancement of the Li capacity of GNRs. Our calculations showed that the achievable Li/O atomic ratio was 4 for the epoxy group (Li4O pyramid cluster) and 3 for the hydroxyl group (Li3(OH) cluster), which suggests that these in-plane functional groups can be more effective in enhancing the Li storage capacity than those terminating the edge sites of graphene-based nanomaterials.

Here, a novel deep blue emitter SBABz4 for use in organic light-emitting diodes (OLED) is investigated. The molecular design of the emitter enables thermally activated delayed fluorescence (TADF), which we examine by temperature-dependent time-resolved electroluminescence (trEL) and photoluminescence (trPL). We show that the dihedral angle between donor and acceptor strongly affects the oscillator strength of the charge transfer state alongside the singlet–triplet gap. The angular dependence of the singlet–triplet gap is calculated by time-dependent density functional theory (TD-DFT). A gap of 15 meV is calculated for the relaxed ground state configuration of SBABz4 with a dihedral angle between the donor and acceptor moieties of 86°. Surprisingly, an experimentally obtained energy gap of 72±5 meV can only be explained by torsion angles in the range of 70°–75°. Molecular dynamics (MD) simulations showed that SBABz4 evaporated at high temperature acquires a distribution of torsion angles, which immediately leads to the experimentally obtained energy gap. Moreover, the emitter orientation anisotropy in a host matrix shows an 80% ratio of horizontally oriented dipoles, which is highly desirable for efficient light outcoupling. Understanding intramolecular donor-acceptor geometry in evaporated films is crucial for OLED applications, because it affects oscillator strength and TADF efficiency.

Nanoprobes such as single-walled carbon nanotubes (SWCNTs) are capable of label-free detection that benefits from intrinsic and photostable near-infrared fluorescence. Despite the growing number of SWCNT-based applications, uncertainty surrounding the nature of double-stranded DNA (dsDNA) immobilization on pristine SWCNTs has limited their use as optical sensors for probing DNA-protein interactions. To address this limitation, we study enzyme activity on unmodified dsDNA strands immobilized on pristine SWCNTs. Restriction enzyme activity on various dsDNA sequences was used to verify the retention of the dsDNA's native conformation on the nanotube surface and to quantitatively compare the degree of dsDNA accessibility. We report a 2.8-fold enhancement in initial enzyme activity in the presence of surfactants. Förster resonance electron transfer (FRET) analysis attributes this enhancement to increased dsDNA displacement from the SWCNT surface. Furthermore, the accessibility of native dsDNA was found to vary with DNA configuration and the spacing between the restriction site and the nanotube surface, with a minimum spacing of four base pairs (bp) from the anchoring site needed to preserve enzyme activity. Molecular dynamics (MD) simulations verify that the anchored dsDNA remains within the vicinity of the SWCNT, revealing an unprecedented bimodal displacement of the bp nearest to SWCNT surface. Together, these findings illustrate the successful immobilization of native dsDNA on pristine SWCNTs, offering a new near-infrared platform for exploring vital DNA processes.

Hole transport materials (HTMs) exhibiting suitable electronic properties, fast hole transport, high hydrophobicity and good oxygen resistance are critical for realizing perovskite solar cells (PSCs) that are stable and exhibit high-performance. Manipulating the length of alkyl chains is a widely adopted strategy that can fine tune the properties of organic materials in order to enhance their performance for various applications. Yet, a systematic exploration of the influence of chain length on those properties most relevant to highly performing HTMs in PSCs is lacking. Multiscale simulations, along with morphological analyses, uncover relationships between alkyl chain length and HTM properties that provide important insights for the optimization of future organic materials.

The reorganization energy (lambda), which quantifies the structural rearrangement of a molecule when accommodating a charge, is a key parameter in the evaluation of charge mobility in molecular solids. However, it is unclear how lambda is influenced by conformational isomerism, which is diverse in amorphous solids. Here, we examine the conformational space of a family of model amorphous organic hole transport materials (HTMs), derived from triphenylamine in a core-arm template, and probe the effect of conformational complexity on lambda. We observe an extreme dependence of lambda on the conformer geometry of sterically congested HTMs, which to the best of our knowledge has not been described previously. These results serve as a cautionary tale that, while extracting the reorganization energy from a single molecular conformer optimized in the gas phase may be appropriate for rigid and sterically unencumbered structures, this approach is not suitable for many state-of-the-art HTMs that contain multiple bulky substituents.

We present a fragment-based decomposition analysis tool (FB-REDA) for the reorganisation energy (lambda). This tool delivers insights on how to rationally design low-lambda organic semiconductors. The contribution of the fragment vibrational modes to the reorganization energy is exploited to identity the individual contributions of the molecular building blocks. The usefulness of the approach is demonstrated by offering three strategies to reduce the reorganization energy of a promising dopant-free hole transport material (TPA1PM, lambda = 213 meV). A reduction of nearly 50% (TPD3PM, lambda = 108 meV) is achieved. The proposed design principles are likely transferable to other organic semiconductors exploiting common molecular building blocks.

We explore several potential dopant-free triphenylamine-based hole transport materials for perovskite solar cells by combining two design strategies: (1) incorporation of multiple arms for mobility enhancement and (2) including Lewis bases that assist in defect passivation. Through multiscale computations along with the analysis of the electronic structure, molecular transport network, and data clustering, we established the relationship among hole mobility, transport parameters, intrinsic molecular properties, and molecular packing. Our results showed that multiarm design can be an effective strategy for 4-fold hole mobility enhancement (from 7 x 10(-6) to 3 x 10(-5) cm(2) V-1 s(-1)) through reducing the reorganization energy and energetic disorder. Furthermore, ionization potential (IP) optimization by changing substituents was performed because the IP decreases with an increasing number of arms. Via an adequate choice of substituents, the IP approaches the minus valence band maximum of MAPbI(3) and the hole mobility is further increased similar to 3-fold. The simulated mobility is in fair agreement with that obtained from field-effect transistors, supporting our computational protocols.