The estimation of electronic couplings between diabatic states is crucial for the comprehension of electron transfer phenomena between molecular systems. Therefore, the development of efficient approximations that enable a very fast, yet accurate, estimation of electronic couplings is an important research goal in the context of organic semiconductors. The most popular methods (diabatization schemes, projection approximations, or methods using fragment molecular orbitals) usually involve the use of electronic structure calculations and can be computationally prohibitive if a large number of electronic coupling estimations is required. In this paper, we propose a novel strategy (CubeMap) to evaluate electronic couplings between molecular pairs in an extremely efficient manner. CubeMap employs the well-established linear relationship between the electronic coupling and the overlap integral between the corresponding molecular orbitals localized on the interacting molecules. In particular, CubeMap is based on the efficient calculation of the overlap integral in real space using molecular orbital grids of moderate size. The CubeMap efficiency partly comes from the fact that only a single electronic structure calculation of an individual molecule (reference geometry) is enough for the subsequent evaluation of overlap integrals and electronic couplings in multiple dimer dispositions. We show that CubeMap is particularly appealing to rapidly estimate the electronic coupling distributions in molecular crystals due to thermal fluctuations (dynamic disorder), which is an important effect for the accurate description of charge transport in organic semiconductors. Compared with the methods usually employed to evaluate electronic couplings, the CubeMap approach drastically reduces the computational cost by several orders of magnitude.

Perovskites solar cells (PSCs) have emerged, since 2009, as the most promising technology to replace/complement crystalline silicon PV. [1] Outstanding results of PCE up to 26.7 % have been obtained using perovskites (eg. MAPbI 3 ) in just a few years of research. The continuous improvement of the efficiency in PSCs has been achieved using commercially available spiro-OMeTAD as hole-transporting material (HTM). However, spiro-OMeTAD is an expensive material due to its difficult purification and multi-step synthetic protocols (in harsh conditions) which limits its future use in large-scale applications. As a consequence, great efforts in the synthesis and characterization of alternative organic low-cost molecules for its application as HTMs have been reported in the recent years, including PAH-based, spiro-containing or dopant-free materials. [2] Our research group reported two doped-HTMs based on electron-rich spiranic scaffolds, namely, spiro-POZ and spiro-PTZ which exhibit a similar performance of the reference material and improved long-term stability (more than 300 days of exposure to ambient conditions and more than 1200 h under continuous 1 sun illumination) in sharp contrast with the reference of spiro-OMeTAD. [3] Motivated by these excellent results, we have designed four new derivatives based on spiro-PTZ functionalized with asymmetric diphenylamine units that have been incorporated in PSCs improving the PCE of the devices up to 25.75%, surpassing clearly the power conversion efficiency and stability of spiro-OMeTAD. Furthermore, large area mini module (25 cm 2 ) also shows an outstanding PCE above 22%, pointing spiro-PTZ derivatives as one of the most efficient HTMs reported in bibliography. References [1] A. Kojima, K. Teshima, Y. Shirai, T. Miyasaka, J. Am. Chem. Soc. 2009 , 131 , 6050-6051. [2] J. Urieta-Mora, I. García-Benito, A. Molina-Ontoria, N. Martín, Chem. Soc. Rev. 2018 , 47 , 8541-8571. [3] J. Urieta-Mora, I. García-Benito, L.-A. Illicachi, J. Calbo, J. Aragó, A. Molina-Ontoria, E. Ortí, N. Martín, M. K. Nazeeruddin, Sol. RRL 2021 , 5 , 2100650. Figure 1

Improving both the efficiency and long‐term stability of perovskite solar cells (PSCs) is critical for their commercial deployment. Despite the widespread use of spiro‐OMeTAD as a hole‐transporting material (HTM), its inhomogeneous doping behavior and susceptibility to moisture and heat have hindered its large‐scale industrial implementation. Here, a family of spiro‐phenothiazine‐based HTMs (PTZ) is reported to address these drawbacks. Among them, the fluorene derivative (PTZ‐Fl) shows a larger Li + affinity and forms a compact interphase by intercalation in the perovskite passivating layer that prevents Li + migration. PSCs incorporating PTZ‐Fl exhibit power conversion efficiencies (PCEs) up to 25.8% (certified 25.2% under reverse scan), retaining 80% of their initial performance after 1000 h under ISOS‐L‐3 protocol. Furthermore, a 5 × 5 cm mini‐module reaches a PCE of 22.1%, surpassing spiro‐OMeTAD‐based PSCs and retaining over 85% of its efficiency after 1100 h under ISOS‐D‐1 protocol. These results demonstrate that PTZ‐Fl not only enables high PCEs but also substantially improves operational stability, offering a promising pathway toward the large‐scale deployment of next‐generation PSCs.

A pillar of our current understanding of the photoluminescence of Ir(III) complexes is the assumption that the population of triplet metal-centered states determines an efficient nonradiative decay to the ground state minimum. Based on that assumption, the energy separation between the emitting state and the minimum-energy crossing point of the triplet metal-centered and ground states has been employed as a key variable for evaluating the ability of Ir(III) complexes to decay nonradiatively. We demonstrate that the strong spin-orbit coupling between the triplet metal-centered and ground state of Ir(III) complexes, together with the sloped topography of their crossing, leads to a significant energy separation between the two states, resulting in a reduced rate of nonradiative ground state recovery. Therefore, we propose that the role of metal-centered states is defined by the tendency of the excited state population to remain trapped in the metal-centered minima.

The in silico determination of the emission quantum yield (Φem) of a cyclometalated Ir(III) complex requires the evaluation of all its possible radiative and nonradiative decays. The task is challenging, particularly when more than one minimum is present on the potential energy surface of the emitting lowest-energy triplet T1, a situation more common than what was previously thought. In the present contribution, we study all possible radiative and nonradiative paths for the two cyclometalated Ir(III) complexes, [Ir(ppy)2(pyim)]+ and [Ir(diFppy)2(dtb-bpy)]+, indeed characterized by T1 minima of both metal-to-ligand charge transfer and ligand-centered nature. Comparing the computed emission quantum yields accounting for all processes and for only those processes in principle more relevant, we aimed at judging the importance of characterizing all decays to provide an accurate estimation of Φem. Evaluating the barrier between emitting T1 and nonradiative 3MC states obtaining the corresponding transition state or approximating the latter using the CI-NEB method, we aimed at judging the importance of performing transition state optimizations. The latter task, due to its intrinsic complexity and poor convergence behavior, is a bottleneck for the characterization of the photophysics of a complex and consequently prevents a more efficient screening of cyclometalated Ir(III) complexes for technological applications.

Herein, the charge transport properties of two organic semiconductors (1 and 2) with tiny differences in the pi-conjugated scaffold but distinct crystal arrangements are thoroughly rationalized by a combined experimental and computational characterization. Compound 1, including 7-azaindole units in the pi-conjugated core, is designed to promote intermolecular hydrogen bonding and induce certain order in the solid-state structure with multiple face-to-face pi-pi interactions. In contrast, compound 2, for which the terminal pyridine rings of the 7-azaindole units are substituted by phenyl rings, thus precluding the formation of intermolecular hydrogen bonds, exhibits the typical herringbone crystal arrangement of acenes. The alkyl chains end-capping the conjugated cores also play a noticeable effect on the molecular arrangement. These structural features determine the performance of the organic semiconductors in organic field-effect transistors (OFETs), with 2 showing a better hole mobility. The computational strategy used to study the charge transport properties sheds light onto the behavior of both compounds, and predicts higher hole mobilities for 2 compared to 1 both in crystal and amorphous phases in line with the experimental measurements. While the origin of the enhanced carrier mobility displayed by 2 in the crystal results from the better intermolecular electronic coupling between adjacent molecules, its higher mobility in the amorphous phase seems to arise from the smaller internal reorganization energy computed for 2 compared to 1.

This work reports the synthesis of Z-shaped PDI (Z-PDI) 1 and explores its self-assembly behavior. The lateral trialkoxybenzamide moieties in compound 1 promote the formation of metastable monomeric units (M*) through intramolecular hydrogen bonds, which undergo kinetically controlled supramolecular polymerization. This process exhibits pathway complexity, yielding H-type aggregates (AggIH) under kinetic control and, remarkably, null aggregates (AggIIn) under thermodynamic control. The conversion follows a competitive pathway, in which both aggregated states compete for the free monomeric species. A combination of experimental data and theoretical calculations reveals that the formation of AggIH is governed by the intermolecular hydrogen bonding between amide groups and the π-stacking of the aromatic cores. The thermodynamically favored null aggregate AggIIn also arises from the same noncovalent interactions but its unique nature stems from a balance between Coulombic and charge-transfer interactions─similar in magnitude yet opposite in sign, resulting in an optical absorption profile nearly identical to that of the monomer. The living supramolecular polymerization of Z-shaped PDI 1 enables the transition from kinetically trapped to thermodynamically stable aggregates. These findings highlight the critical role of the molecular design in achieving null aggregation and pathway complexity, while emphasizing the importance of π-overlap, intermolecular distance, and chromophore orientation in determining the nature of the resulting supramolecular assemblies.

We show an unexpected aggregation phenomenon of a long oligoyne ( Py[16] ) with 16 contiguous triple bonds and endcapped with bulky 3,5-bi(3,5-bis- tert -butylphenyl)pyridine groups. Aggregation of 1D π-conjugated oligoyne chains is rare given the minimal π–π intermolecular interactions as well as its flexibility that works against self-assembly. In dilute solutions, the reversible aggregation of Py[16] initiates at low temperature in the range of 140–180 K, and is not observed for shorter oligoynes in this series. Cryogenic UV/Vis electronic absorption spectra and vibrational Raman spectra with different laser wavelength lines tuning from in-resonance to off-resonance conditions have been used to extract the vibrational features characterizing the monomer and aggregate species. Theoretical calculations complement the spectroscopic findings.

The columnar arrangement of bowl-shaped aromatics is a promising strategy for producing high-performing semiconductors. However, the structural factors that dictate the self-assembly of these molecules remain poorly understood. Herein, we show how chirality and peripheral substitution affect the columnar assembly of subphthalocyanines (SubPcs) in solution. Both aspects are found to influence the structure, stability, and formation mechanism of the supramolecular polymer obtained. Whereas enantiopure tri-substituted SubPcs cooperatively polymerize into homochiral head-to-tail arrays, racemic mixtures socially self-sort, leading to heterochiral columnar polymers. In sharp contrast, hexa-substituted SubPcs polymerize following an isodesmic mechanism, producing highly robust columnar systems. As elucidated by molecular dynamics calculations, the conformational flexibility of these SubPcs, as well as the number of peripheral groups able to intermolecularly interact, underlie these significant differences. The results presented herein pave the way for the realistic application of bowl-shaped π-compounds.

7‐Azaindole has been integrated as building block with complementary N‐H···N hydrogen bonding sites for the synthesis of a tetrahedral molecular tecton, namely tetra(α‐carbolin‐6‐yl)methane, TACM. The self‐assembly of this molecule results in a 3D hydrogen‐bonded organic framework (HOF). This supramolecular structure constitutes a crystalline microporous material with an extraordinary thermal and chemical robustness. Single crystal X‐ray diffraction reveals how the five‐fold catenation of diamonoid systems, stabilized by hydrogen bonds and π‐π interactions, form an interpenetrated network with monodimensional channels. The structural features of the crystalline material are also observed by transmission electron microscopy (TEM). Additionally, the microporosity of the activated TACM‐HOF is characterized by gas sorption (N2, CO2, CH4 and H2) experiments performed at different pressures. A selective adsorption is observed for CO2 uptake and TACM‐HOF also presents a good adsorption capacity for H2 among supramolecular organic frameworks.

A comprehensive investigation of two new molecular triads incorporating the diketopyrrolopyrrole unit into a quinoidized thienothiophene skeleton, which is further end‐capped with dicyanomethylene (DPP‐TT‐CN) or phenoxyl groups (DPP‐TT‐PhO), has been carried out. A combination of UV‐Vis‐NIR and infrared spectroelectrochemical techniques and cryogenic UV‐Vis‐NIR absorption spectroscopy supported by theoretical calculations has been used. The main result is the formation of similar H‐aggregates in the dimerization process of the neutral molecules and of the charged anionic species. The experimental absorption spectra of the aggregated species are accurately reproduced by quantum chemical calculations using the Spano’s model, including excitonic coupling for the dimeric forms and full vibronic resolution of the absorption bands. The strong excitonic coupling taking place is key to understand the electronic structure of the dimeric aggregates and has been instrumental to disentangle the type of H‐aggregation. This study is of relevance to get a better understanding of the molecular aggregation of organic p‐conjugated chromophores and is useful as a guideline for the refinement of the engineering of molecular materials for which supramolecular design is required.

Herein, we explore, from a theoretical perspective, the nonradiative photoinduced processes (charge separation and energy transfer) within a family of donor–acceptor supramolecular complexes based on the electron-donor truxene-tetrathiafulvalene (truxTTF) derivative and a series of curved fullerene fragments (buckybowls) of different shapes and sizes (C30H12, C32H12, and C38H14) as electron acceptors that successfully combine with truxTTF via non-covalent interactions. The resulting supramolecular complexes (truxTTF·C30H12, truxTTF·C32H12, and truxTTF·C38H14) undergo charge-separation processes upon photoexcitation through charge-transfer states involving the donor and acceptor units. Despite the not so different size of the buckybowls, they present noticeable differences in the charge-separation efficiency owing to a complex decay post-photoexcitation mechanism involving several low-lying excited states of different natures (local and charge-transfer excitations), all closely spaced in energy. In this intricate scenario, we have adopted a theoretical approach combining electronic structure calculations at (time-dependent) density functional theory, a multistate multifragment diabatization method, the Marcus–Levitch–Jortner semiclassical rate expression, and a kinetic model to estimate the charge separation rate constants of the supramolecular heterodimers. Our outcomes highlight that the efficiency of the photoinduced charge-separation process increases with the extension of the buckybowl backbone. The supramolecular heterodimer with the largest buckybowl (truxTTF·C38H14) displays multiple and efficient electron-transfer pathways, providing a global photoinduced charge separation in the ultrafast time scale in line with the experimental findings. The study reported indicates that modifications in the shape and size of buckybowl systems can give rise to attractive novel acceptors for potential photovoltaic applications.

Our experimental and theoretical studies have inferred that tin bromide is more susceptible to form higher order 2D Ruddlesden-Popper or 3D perovskite nanostructures than lead bromide.

H-bonded N-heterotriangulene (NHT) supramolecular polymers offer a nice playground to explore the nature and dynamics of electronic excitations in low-dimensional organic nanostructures. Here, we report on a comprehensive molecular modeling of the excited-state electronic structure and optical properties of model NHT stacks, highlighting the important role of intermolecular charge-transfer (CT) excitations in shaping their optical absorption and emission lineshapes. Most importantly, we show that the coupling between the local and CT excitations, modulated by the electric fields induced by the presence of polar amide groups forming H-bonded arrays along the stacks, significantly increases the resulting hybrid exciton bandwidth. We discuss these findings in the context of the efficient transport of singlet excitons over the μm length scale reported experimentally on individual self-assembled nanofibers with molecular-scale diameter.

If we aim to develop efficient synthetic models of protein receptors and enzymes, we must understand the relationships of intra- and intermolecular interactions between hosts and guests and how they mutually influence their conformational energy landscape so as to adapt to each other to maximize binding energies and enhance substrate selectivities. Here, we introduce a novel design of cofacial (ZnII)bisporphyrin cages based on dynamic imine bonding, which is synthetically simple, but at the same time highly robust and versatile, affording receptors composed of only sp 2-hybridized C and N atoms. The high structural rigidity of these cages renders them ideal hosts for ditopic molecules that can fit into the cavity and bind to both metal centers, leading to association constants as high as 109 M-1 in chloroform. These strong binding affinities are a consequence of the remarkable chelate cooperativities attained, with effective molarity (EM) values reaching record values over 103 M. However, we discovered that the cages can still adapt their structure to a more compact version, able to host slightly smaller guests. Such a conformational transition has an energy cost, which can be very different depending on the direction of the imine linkages in the cage skeleton and which results in EM values 2-3 orders of magnitude lower. This interplay between cooperativity and conformational adaptability leads to strong and unusual selectivities. Not only these metalloporphyrin receptors can choose to bind preferably to a particular guest, as a function of its size, but also the guest can select which host to bind, as a function now of the host's conformational rigidity. Such highly cooperative and selective associations are lost, however, in related flexible receptors where the imine bonds are reduced.

Herein, Cu(II)Pcs and Ni(II)Pcs peripherally tetra‐functionalized with 5‐hexylthiophene (HT), 5‐hexyl‐2,2′‐bithiophene (HBT), and tertbutyl groups (TB) are readily synthesized and employed as hole‐transporting materials (HTMs) in mixed‐ion perovskite ([FAPbI 3 ] 0.85 [MAPbBr 3 ] 0.15 ) solar cells, achieving power conversion efficiencies (PCEs) up to 20.0%. Remarkably, both the peripheral functionalization and the central metal are found to play a role in the performance. Through a combination of experimental and theoretical techniques, it is found that the simplest HTM, TB‐CuPc, is the best‐performing HTM primarily due to its higher hole mobility and a more appropriate highest‐occupied molecular orbital, whose enables efficient hole extraction without open‐circuit voltage ( V oc )losses. This derivative leads to PCEs of 19.96%, which are among the highest values for Pc‐based HTMs. Importantly, devices incorporating these HTMs present significantly higher stability compared to those based on spiro‐OMeTAD. The results here presented pave the way for more realistic, efficient, and inexpensive photovoltaic devices using phthalocyanine derivatives.

The exponential effort in the design of hole-transporting materials (HTMs) during the last decade has been motivated by their key role as p-type semiconductors for (opto)electronics. Although structure-property relationships have been successfully rationalized to decipher optimal site substitutions, aliphatic chain lengths or efficient aromatic cores for enhanced charge conduction, the impact of molecular shape, material morphology and dynamic disorder has been generally overlooked. In this work, we characterize by means of a multi-level theoretical approach the charge transport properties of a novel planar small-molecule HTM based on the indoloindole aromatic core (IDIDF), and compare it with spherical spiro-OMeTAD. Hybrid DFT calculations predict moderate band dispersions in IDIDF associated to the main transport direction characterized by π-π stacked molecules, both between the indoloindole cores and the thiophene groups. Strongly coupled dimers show relevant non-covalent interactions (NCI), indicating that NCI surfaces are a necessary but not exclusive requirement for large electronic couplings. We evidence remarkable differences in the site energy standard deviation and electronic coupling distributions between the conduction paths of IDIDF and spiro-OMeTAD. Despite the spherical vs. planar shape, theoretical calculations predict in the static crystal strong direction-dependent charge transport in the two HTMs, with ca. one-order-of-magnitude higher mobility (μ) for IDIDF. The dynamical disorder promoted by finite temperature effects in the crystal leads to a reduction in the hole transport properties in both HTMs, with maximum μ values of 2.42 and 4.2 × 10-2 cm2 V-1 s-1 for IDIDF and spiro-OMeTAD, respectively, as well as a significant increase in the transport anisotropy in the latter. Finally, the impact of the material amorphousness in the hole mobility is analysed by modelling a fully random distribution of HTM molecules. An average (lower-bound) mobility of 1.1 × 10-3 and 4.9 × 10-5 cm2 V-1 s-1 is predicted for planar IDIDF and spherical spiro-OMeTAD, respectively, in good accord with the experimental data registered in thin-film devices. Our results demonstrate the strong influence of molecular shape, dynamic structural fluctuations and crystal morphology on the charge transport, and pose indoloindole-based HTMs as promising materials for organic electronics and photovoltaics.

The theoretical calculation of the temperature-dependent nonradiative decay rate constant is fundamental for predicting the usefulness of transition-metal complexes for technological applications. Such a computation implies the determination of the barriers separating the emitting triplet state from metal-centered states, which are key mediators of this type of radiationless relaxation. We here do so for the two green-emitting cyclometalated Ir(III) complexes, [Ir(ppy)2(pyim)]+ and [Ir(diFppy)2(dtb-bpy)]+, of general formula [Ir(C∧N)2(N∧N)]+, performing DFT calculations with both B3LYP and PBE0 functionals. On the basis of the obtained results and the comparison with the experimental nonradiative decay rate constants, we conclude that B3LYP provides too low energy barriers to the metal-centered states, while the PBE0 provides reasonable values. We consequently recommend to avoid the use of the commonly employed B3LYP functional for the evaluation of such an energy barrier for cyclometalated Ir(III) complexes.

Polyethylene terephthalate (PET) is the most abundant polyester plastic, widely used in textiles and packaging, but, unfortunately, it is also one of the most discarded plastics after one use. In the last years, the enzymatic biodegradation of PET has sparked great interest owing to the discovery and subsequent mutation of PETase-like enzymes, able to depolymerize PET. FAST-PETase is one of the best enzymes hitherto proposed to efficiently degrade PET, although the origin of its efficiency is not completely clear. To understand the molecular origin of its enhanced catalytic activity, we have carried out a thorough computational study of PET degradation by the FAST-PETase action by employing classical and hybrid (QM/MM) molecular dynamics (MD) simulations. Our findings show that the rate-limiting reaction step for FAST-PETase corresponds to the acylation stage with an estimated free energy barrier of 12.1 kcal mol-1, which is significantly smaller than that calculated for PETase (16.5 kcal mol-1) and, therefore, supports the enhanced catalytic activity of FAST-PETase. The origin of this enhancement is mainly attributed to the N233K mutation, which, although sited relatively far from the active site, induces a chain folding where the Asp206 of the catalytic triad is located, impeding that this residue sets effective H-bonds with its neighboring residues. This effect makes Asp206 hold a more basic character compared to the wild-type PETase and boosts the interaction with the protonated His237 of the catalytic triad in the transition state of acylation, with the consequent decrease of the catalytic barrier and acceleration of the PET degradation reaction.

In the present contribution, the following three cyclometallated Ir(III) complexes were theoretically investigated using density functional theory calculations to explain their different photophysical properties: [Ir(ppy)2(bpy)]+, where Hppy is 2-phenylpyridine and bpy is 2,2'-bipyridine, [Ir(ppy)2(pbpy)]+, where pbpy is 6-phenyl-2,2'-bipyridine, and [Ir(ppy)2(dpbpy)]+, where dpbpy is 6,6'-diphenyl-2,2'-bipyridine. Despite sharing the same molecular skeleton, with the only difference being the addition of one or two phenyl groups attached to the ancillary bpy ligand, the complexes show different emission quantum yields in CH2Cl2 solution (0.196, 0.049 and 0.036, respectively). Such a behavior was previously justified as a consequence of a different ability to non-radiatively decay through an axial metal-centered (MC) triplet state. In the present contribution, a new non-radiative decay path has been characterized to be mediated by the so-called equatorial MC states, in which an Ir-Nbpy bond is elongated instead of an Ir-Nppy bond as observed in the axial MC states. The decay path involving the equatorial MC states is more favorable than that associated with the axial MC states, and the different ability to decay through the former better explains the photoemission properties exhibited by the three complexes.